P-G-19—Procedure for the verification and reverification of the primary elements of orifice meters pursuant to the requirements of PS-G-19

Category: Gas
Issue date: 2022-07-12
Effective date: 2022-07-12
Revision number: 2
Supersedes: P-G-19 (rev. 1)


Table of contents


1.0 Purpose

This procedure provides instructions for the verification and reverification of the primary elements of orifice meters pursuant to the requirements of provisional specifications PS-G-19. It applies to the primary elements of orifice meters used in trade or custody transfer applications, with the exception of those for which conditional permission has been granted for use in service without verification and sealing.

Notes: While an orifice meter also includes secondary components such as flow recorders, flow computers and transducers, this document does not provide instructions for the verification or reverification of these devices.

2.0 Definitions

Refer to PS-G-19 for definitions of terms that may be relevant to this procedure.

3.0 References

4.0 Safety

4.1 Measurement Canada's health and safety policy

Inspectors must be aware of and fully conform to Measurement Canada's (MC) health and safety policy, including the provisions relating to personal protective equipment for the in situ inspection of the primary elements of orifice meters.

4.2 Contractor and third-party safety and security requirements

Subject to the policy established in GEN-16, inspectors must be aware of and conform to the contractor's and any third-party safety and security requirements that apply to the work site.

4.3 Potential hazards

Inspectors must be aware of the following potential hazards which may occur during transport to and from the work site and while at the work site:

  • Asphyxiation
  • Aircraft
  • Extreme environmental conditions
  • Flammability
  • Heavy equipment in operation or in motion
  • High pressure
  • Isolation in case of emergency response
  • Noise
  • Road conditions
  • Toxic and irritant gas
  • Tripping
  • Wild animals

4.4 Responsibilities of the contractor's representative

The contractor's representative is responsible for the following:

  • Making any adjustments, alterations and connections to the contractor's equipment;
  • Disassembling the contractor's equipment, as required;
  • Supplying all piping, fittings, tubing and any additional equipment required to perform the inspection in a safe, efficient and convenient manner;
  • Monitoring the work site for the presence of flammable and poisonous gases in the air during the inspection;
  • Identifying a contact person for any third-party establishment and providing them with additional information (e.g. dates of inspection, required and additional safety training courses, government vehicle information), as required.

Notes: Inspectors may provide advice, guidance and assistance to the contractor's representative as required.

5.0 Inspection apparatus

5.1 Measuring apparatus

The following measuring apparatus are required:

  • Certified thermometer
  • Gauge block set
  • Surface plate
  • Surface roughness tester

Notes: Certified gauge blocks are used to ensure the calibration of measurement equipment (e.g. micrometres).

5.2 Additional equipment

The following additional equipment is required:

  • Absorbent towels
  • Bevel protractor
  • Calculator
  • Dial bore gauges
  • Dial or digital calipers
  • Eccentricity gauge
  • Flashlight
  • Inside micrometres
  • Letter stamp set
  • Number stamp set
  • Outside micrometres
  • Recess gauge
  • Small hole gauges
  • Small square
  • Straight edge
  • Tape measures (25'/762 cm and 100'/3048 cm)
  • Taper gauge
  • Tap-hole-to-tap-hole gauge
  • Tap-hole-to-orifice-plate gauge
  • Verification marks (sticker type)
  • Verification stamp (maple leaf or crown)

6.0 Inspection worksheet

The inspection worksheet referred to in this procedure may be obtained by contacting any MC electricity and gas regional office.

7.0 Assessment of conformity with administrative requirements

7.1 General

  1. Obtain and review the applicable edition of AGA Report No. 3.
  2. Examine the primary element of the orifice meter and determine what components are used.
  3. Obtain and review the notices of approval of the orifice fitting and flow conditioner, where applicable.

7.2 Markings

  1. Examine the components of the primary element and assess their conformity with the marking requirements of PS-G-19.
  2. Record the required markings of the components of the primary element and any nonconformity with the requirements specified on the inspection worksheet.

8.0 Assessment of conformity with technical requirements

8.1 General

  1. Where the inspection is conducted at the operational location, ask the contractor or owner to disassemble the orifice meter run before your arrival in order to allow you to access each component of the primary element.
  2. Ensure that all welds within the minimum lengths of the meter tube have been suitably ground down and the tubes are clean to protect measuring equipment.
  3. Ensure that all orifice flanges have been welded straight (i.e. to the same axis) to the preceding fitting.
  4. Ensure all orifice flanges or fittings are marked with same pressure ranges (e.g. American National Standards Institute [ANSI] 300, ANSI 600).
  5. Refer to appendix A, B, C or D, based on the applicable edition of AGA Report No. 3, for the verification and reverification of the following items:
    • Orifice meter run configuration
    • Thermometer wells
    • Orifice meter tubes
    • Flow straighteners (where applicable)
    • Orifice flanges
    • Orifice fittings (where applicable)
    • Pressure taps
    • Orifice plates

8.2 Flow conditioner (where applicable)

  1. Examine the flow conditioner and assess its conformity with the requirements of S-G-04.
  2. Record any nonconformity on the inspection worksheet.

9.0 Sealing

Refer to PS-G-19 for the requirements pertaining to the sealing of the conforming primary elements of orifice meters.

10.0 Inspection certificate

Complete and issue an inspection certificate in accordance with GEN-27 and section 21 of the Electricity and Gas Inspection Regulations.

Notes: It is recommended that the certificate contain, or be accompanied by, the following information:

  • Orifice meter inspection number;
  • Orifice meter manufacturer's name;
  • Orifice fitting serial number and model number;
  • Orifice fitting manufacturer's name;
  • Orifice meter nominal inside diameter ( ID ) or reference meter tube internal diameter ( Dr );
  • Number of the figure in AGA Report No. 3 or installation type corresponding to the meter run configuration;
  • Average ID measured one inch upstream of the orifice plate or the measured meter tube internal diameter ( Dm );
  • Maximum diameter ratio (β) to be used;
  • Maximum orifice size to be used;
  • The conformance of the primary element of the orifice meter with these requirements;
  • Comments explaining the reason for the rejection or reduction of the diameter ratio (β) if it is less than the maximum allowable diameter ratio (β) prescribed in PS-G-19.

11.0 Fees

Charge the fee for the inspection of the meter tube, orifice plate, flow conditioner (where used) and orifice fitting (where used) as established in Schedule 1, Part IV of the Electricity and Gas Inspection Regulations.

12.0 Nonconformity and defect reporting

Report details of any nonconformity or defects identified during the inspection to the regional gas specialist for review and follow-up.

13.0 Revision

The purpose of revision 2 was to remove the reference to GEN-17—Interpretation of the Schedule of Fees because it has been repealed and all future service fees and charging practices will comply with the Service Fees Act and the fee schedules listed in the Weights and Measures Regulations and the Electricity and Gas Inspection Regulations.

Appendix A—Verifications and reverifications of primary elements in accordance with the American Gas Association Report No. 3, first edition, 1969

A1.0 Orifice meter run configuration

  1. Confirm that the meter run is installed either horizontally or vertically (with the gas flowing downward).
  2. Refer to figures 3A through 3E in 2.4 of the report (1969) to determine which figure corresponds to the configuration of the meter run being inspected and select the applicable figure on the inspection worksheet.

    Notes:

    • For installations not explicitly covered in figures 3B through 3E, Figure 3A applies.
    • The notations listed in the report (1969) for the figure which corresponds to the configuration of the meter run being inspected are important.
  3. Measure the following linear dimensions of the orifice meter tube as required in the dimension sketch of the inspection worksheet and record them on the worksheet:
    • Overall upstream tube length (A or A');
    • Overall downstream tube length (B);
    • Upstream tube length from the orifice plate to the downstream end of the straightening vanes or flow conditioner if either is used (C);
    • Upstream tube length from the downstream end of the straightening vanes or flow conditioner to the extreme upstream end of the orifice meter tube (C').
    • Notes: Where full bore ball valves are used, they may be considered straight pieces of pipe.
  4. Refer to the graph of the corresponding figure in the report (1969) to determine if the measured dimensions meet the minimum length requirements for the maximum allowable diameter ratio (β) prescribed in PS-G-19.

    Notes: If a flow conditioner is used, ensure that it meets the minimum length requirements. There is no provision for β reduction with this device, so if the minimum length requirements are not met, the orifice meter is rejected.

  5. If the measured dimensions do not meet the minimum length requirements for the maximum allowable β prescribed in PS-G-19, refer to the graph of the corresponding figure in the report (1969) to determine which tube length restricts β the most.

    Notes: As β decreases, the meter tube length requirements decrease.

  6. Ensure the lowest β is greater than the minimum allowable β prescribed in PS-G-19 and record it on the inspection worksheet.
  7. Record the conformance status (i.e. accepted, accepted with a restricted β or rejected) of the meter tube on the inspection worksheet.
  8. Where β does not meet the requirements of PS-G-19, the contractor's representative may make any necessary adjustments. Repeat all required measurements in accordance with this section and record the "as left" data and conformance status on the same inspection worksheet or a new one.

    Notes: Where the meter tube does not meet the specified requirements, the orifice meter run cannot be used in trade or custody transfer applications until it has been corrected and reverified.

A2.0 Thermometer wells

  1. Measure the distance between the thermometer well and the orifice plate as well as the distance between the thermometer well and the flow conditioner (if used), and record the measurements on the inspection worksheet.
  2. Refer to 2.9 of the report (1969) for the required location of the thermometer well.
  3. Record the conformance status (i.e. accepted or rejected) of the thermometer well on the inspection worksheet.
  4. Where the thermometer well does not meet the requirements of AGA Report No. 3, first edition, 1969, the contractor's representative may make any necessary adjustments. Repeat all required measurements in accordance with this section and record the "as left" data and conformance status on the same inspection worksheet or a new one.

    Notes: Where the thermometer well does not meet the specified requirements, the orifice meter run cannot be used in trade or custody transfer applications until it has been corrected and reverified.

A3.0 Orifice meter tube

This section applies to the meter tube, which includes the straight pipes of the same diameter preceding (upstream) and following (downstream) the orifice plate and the flow conditioner, if used.

A3.1 Inside surface of the orifice meter tube

  1. Using the tester, measure the surface roughness of the inside pipe walls upstream and downstream of the orifice plate, and record the measurements on the inspection worksheet.
  2. Confirm that the inside pipe walls meet the requirements specified in 2.3.2 of the report (1969).
  3. Record the conformance status (i.e. accepted or rejected) of the inside surface of the orifice meter tube on the inspection worksheet.
  4. Where the inside surface of the orifice meter tube does not meet the requirements of AGA Report No. 3, first edition, 1969, the contractor's representative may make any necessary adjustments. Repeat all required measurements in accordance with this section and record the "as left" data and conformance status on the same inspection worksheet or a new one.

    Notes: Where the inside surface of the orifice meter tube does not meet the specified requirements, the orifice meter run cannot be used in trade or custody transfer applications until it has been corrected and reverified.

A3.2 Inside diameter of the orifice meter tube

  1. Measure the inside diameter of the upstream and downstream tubes as per 2.3.3 and 2.3.4 of the report (1969) and record the measurements on the inspection worksheet.

    Notes:

    • Depending on the figure selected in A1.0(b), the following sections are measured and no meter tube diameter measurements are required beyond these sections:
      • A or C;
      • B; and
      • Upstream of the straightening vane within section A'.
    • The report (1969) permits inside tube diameter measurements upstream of the straightening vane, but they are seldom performed.
    • When a meter tube is made up of more than one part, such as a pipe, a flange and a fitting, the second and third diameter measurements must be made in the different parts or equivalent.
    • It is recommended to measure the inside diameters at the worst conditions within the tube (often at a weld or where the pipe is out-of-round or damaged) to ensure uniformity of the inside surface of the pipe and fitting.
    • The most suitable device for measuring the inside diameter of a meter tube is a dial bore gauge, which can be slid down the tube to thoroughly search for irregularities such as ridges and hollows. Inside micrometres can also be used; however, they much slower and less thorough, which can result in inaccurate results.
  2. Compare the inside diameter measurements to the tolerances prescribed in 2.3.5 of the report (1969).

    Notes: The tolerances apply to the difference between the following:

    • The average inside diameter (D) of each section of tube and the published (ideal) inside diameter (PID) for that particular nominal pipe size and schedule, compared to the PID.

      % = ( Average D PID PID ) × 100

    • The maximum and minimum measured inside diameters of each section of tube, compared to the PID.

      % = ( Max . diameter min . diameter PID ) × 100

  3. If the inside diameter measurements do not meet the tolerances prescribed in 2.3.5 of the report (1969) for the maximum allowable β prescribed in PS-G-19, refer to the appropriate graph in the report (1969) to determine what β will allow a tolerance equal to or greater than the actual diameter measurements.
  4. Ensure the lowest β meets the minimum allowable β prescribed in PS‑G‑19 and record it on the inspection worksheet.
  5. Record the conformance status (i.e. accepted, accepted with a restricted β or rejected) of the inside diameter of the meter tube on the inspection worksheet.
  6. Where β does not meet the requirements of PS-G-19, the contractor's representative may make any necessary adjustments. Repeat all required measurements in accordance with this section and record the "as left" data and conformance status on the same inspection worksheet or a new one.

    Notes: Where the inside diameter of the orifice meter tube does not meet the specified requirements, the orifice meter run cannot be used in trade or custody transfer applications until it has been corrected and reverified.

A4.0 Straightening vanes (where applicable)

  1. Examine the straightening vane and assess its conformity with the requirements specified in 2.5 of the report (1969) and PS-G-19.
  2. Ensure the straightening vane fits in the meter tube by installing it at the proper location.
  3. Record any nonconformity on the inspection worksheet.

A5.0 Orifice flanges (where applicable)

  1. Examine the orifice flanges and assess their conformity with the requirements specified in 2.6 of the report (1969).
  2. Record any nonconformity or β reduction on the inspection worksheet.

A6.0 Orifice fittings (where applicable)

  1. Ensure the orifice fitting is approved by MC.
  2. Examine the orifice fitting and assess its conformity with the requirements in 2.7 of the report (1969), the requirements of PS-G-19 and its notice of approval.
  3. Record any nonconformity on the inspection worksheet.

A7.0 Pressure tap holes

A7.1 Pressure tap hole drilling and edges

Ensure the drilling and edges of the pressure tap holes meet the requirements specified in 2.8.3, 2.8.5 and 2.8.6 of the report (1969).

A7.2 Pressure tap hole locations

  1. Measure the distances from the centreline of the tap hole to the orifice plate surface, both upstream and downstream, and record the measurements on the inspection worksheet.
  2. Compare the measurements to the tolerances prescribed in 2.8.1 or 2.8.2 of the report (1969).
  3. If the measurements do not meet the tolerances prescribed in 2.8.1 or 2.8.2 of the report (1969) for the maximum allowable β prescribed in PS‑G‑19, refer to Figure 5 in the report to determine what β will allow a tolerance equal to or greater than the actual measurements.
  4. Ensure the lowest β meets the requirement for the minimum allowable β prescribed in PS-G-19 and record it on the inspection worksheet.
  5. Record the conformance status (i.e. accepted, accepted with a restricted β or rejected) of the pressure tap hole locations on the inspection worksheet.
  6. Where pressure tap hole locations do not to meet the requirements of the report (1969), the contractor's representative may make any necessary adjustments. Repeat all required measurements in accordance with this section and record the "as left" data and conformance status on the same inspection worksheet or a new one.

    Notes: Where pressure tap holes locations do not meet the specified requirements, the orifice meter run cannot be used in trade or custody transfer applications until it has been corrected and reverified.

A7.3 Pressure tap hole diameters

  1. Measure the diameter of the pressure tap holes on the inner surface of the pipe and record the measurement on the inspection worksheet.
  2. Compare the measurement to the tolerances prescribed in 2.8.4 of the report (1969).
  3. Record the conformance status (i.e. accepted or rejected) of the pressure tap hole diameter on the inspection worksheet.
  4. Where the pressure tap hole diameter does not meet with the requirements of the report (1969), the contractor's representative may make any necessary adjustments. Repeat all required measurements in accordance with this section and record the "as left" data and conformance status on the same inspection worksheet or a new one.

    Notes: Where pressure tap hole diameter does not meet the specified requirements, the orifice meter run cannot be used in trade or custody transfer applications until it has been corrected and reverified.

A8.0 Orifice plates

This section applies to all orifice plates at the metering station.

A8.1 Installation of an orifice plate within the meter tube

A8.1.1 Concentricity
  1. Measure the dimensions of the orifice plate as required on the dimension sketch of the inspection worksheet and record the measurements on the worksheet.
  2. Ensure the orifice plate is concentric with the inside diameter of the meter tube or orifice fitting within the tolerances prescribed in 2.2.4 of the report (1969) by calculating the eccentricity parallel to the vertical and horizontal axes.
  3. Record the conformance status (i.e. accepted, rejected) of the orifice plate concentricity on the inspection worksheet.
  4. Where the orifice plate is not concentric with the inside diameter of the meter tube or orifice fitting, the contractor's representative may make any necessary adjustments. Repeat all required measurements in accordance with this section and record the "as left" data and conformance status on the same inspection worksheet or a new one.

    Notes: Where the orifice plate is not concentric, the orifice meter run cannot be used in trade or custody transfer applications until it has been corrected and reverified.

A8.1.2 Perpendicularity
  1. When the orifice plate is in position within the meter tube, measure the distance (depth) from the downstream orifice plate face to a reference point further downstream and record the measurement on the inspection worksheet.
  2. Ensure the orifice plate is perpendicular to the axis of the pipe as per 2.2.2 of the report (1969) by calculating the deviations from the vertical and horizontal axes.
  3. Record the conformance status (i.e. accepted, rejected) of the orifice plate perpendicularity on the inspection worksheet.
  4. Where the orifice plate is not perpendicular to the axis of the pipe when in position between the orifice flanges or in the orifice fitting, the contractor's representative may make any necessary adjustments. Repeat all required measurements in accordance with this section and record the "as left" data and conformance status on the same inspection worksheet or a new one.

    Notes: Where the orifice plate is not perpendicular, the orifice meter run cannot be used in trade or custody transfer applications until it has been corrected and reverified.

A8.2 Orifice plate surface roughness

  1. Using the tester, measure the surface roughness of the orifice plate at three sections and record the measurements on the inspection worksheet.
  2. Compare the measurements to the tolerances prescribed in 2.2.1 of the report (1969).
  3. Record the conformance status (i.e. accepted or rejected) of the surface roughness of the orifice plate on the inspection worksheet.
  4. Where applicable, cancel any verification stamp to indicate the rejection of the orifice plate.

    Notes: Where the orifice plate surface roughness does not meet the specified requirements, the orifice plate cannot be used in trade or custody transfer applications.

A8.3 Orifice plate bore edge

  1. Evaluate the sharpness of the square edge of the orifice plate bore by running a fingernail around the upstream edge to detect any irregularities. Ensure the upstream edge is square and sharp.

    Notes:

    • The edge must not reflect light when viewed without magnification, as per 2.2.3 of the report (1969).
    • If a nick can be felt with a fingernail, it can usually be seen in a good light, such as sunlight.
  2. Record the conformance status (i.e. accepted or rejected) of the orifice plate bore edge on the inspection worksheet.
  3. Where applicable, cancel any verification stamp to indicate the rejection of the orifice plate.

    Notes: Where the orifice plate bore edge does not meet the specified requirements, the orifice plate cannot be used in trade or custody transfer applications.

A8.4 Orifice plate flatness

  1. Measure the flatness of the orifice plate as per Figure 1B of the report (1969) and record the measurement on the inspection worksheet.
  2. Compare the measurements to the tolerances prescribed in 2.2.2 of the report (1969).
  3. Record the conformance status (i.e. accepted or rejected) of the orifice plate flatness on the inspection worksheet.
  4. Where applicable, cancel any verification stamp to indicate the rejection of the orifice plate.

    Notes: Where the orifice plate flatness does not meet the specified requirements, the orifice plate cannot be used in trade or custody transfer applications for custody transfer or trade purposes.

A8.5 Orifice plate bore diameter ( d ) and roundness

  1. Ensure the β stamped on the plate is within the range prescribed in PS-G-19 and record it on the inspection worksheet.
  2. Measure the following dimensions as required on the dimension sketch of the inspection worksheet and record them on the worksheet:
    • Actual bore diameter ( d ) at three different diameters, evenly spaced;
    • Orifice edge thickness ( e );
    • Orifice plate thickness ( E );
    • Diameter of the finished area on the plate ( D ); and
    • Angle of the bevel (Ɵ).
  3. Compare the measurements to the tolerances prescribed in Figure 1A and Table 1 in the report (1969).
  4. Record the conformance status (i.e. accepted or rejected) of the orifice plate bore diameter and roundness on the inspection worksheet.
  5. Where applicable, cancel any verification stamp to indicate the rejection of the orifice plate.

    Notes: Where the orifice plate bore diameter is greater than that permitted by a reduced β or does not fully meet the specified requirements, the orifice plate cannot be used in trade or custody transfer applications.

Appendix B—Verifications and reverifications of primary elements in accordance with American Gas Association Report No. 3, second edition, 1985

B1.0 Orifice meter run configuration

  1. Confirm that the meter run is installed either horizontally or vertically (with the gas flowing downward).
  2. Refer to figures 4 through 8 in 4.4 of the report (1985) to determine which figure corresponds to the configuration of the meter run being inspected and select the applicable figure on the inspection worksheet.

    Notes:

    • For installations not explicitly covered in figures 4 through 8, Figure 4 applies.
    • The notations listed in the report (1985) for the figure which corresponds to the configuration of the meter run being inspected are important.
  3. Measure the following linear dimensions of the orifice meter tube as required on the dimension sketch of the inspection worksheet and record them on the worksheet:
    • Overall upstream tube length (A or A');
    • Overall downstream tube length (B);
    • Upstream tube length from the orifice plate to the downstream end of the straightening vane or flow conditioner (if either is used) (C); and
    • Upstream tube length from the downstream end of the straightening vane or flow conditioner to the extreme upstream end of the orifice meter tube (C').

      Notes: Where full bore ball valves are used, they may be considered straight pieces of pipe.

  4. Refer to the graph of the corresponding figure in the report (1985) to determine if the measured dimensions meet the minimum length requirements for the maximum allowable diameter ratio (β) prescribed in PS-G-19.

    Notes: If a flow conditioner is used, ensure that it meets the minimum length requirements. There is no provision for β reduction with this device, so if the minimum length requirements are not met, the orifice meter is rejected.

  5. If the measured dimensions do not meet the minimum length requirements for the maximum allowable β prescribed in PS-G-19, refer to graph of the corresponding figure in the report (1985) to determine which tube length restricts β the most.

    Notes: As β decreases, the tube length requirements decrease.

  6. Ensure this lowest β meets the minimum allowable β prescribed in PS-G-19 and record it on the inspection worksheet.
  7. Record the conformance status (i.e. accepted, accepted with a restricted β or rejected) of the meter run on the inspection worksheet.
  8. Where β does not meet the requirements of PS-G-19, the contractor's representative may make any necessary adjustments. Repeat all required measurements in accordance with this section and record the "as left" data and conformance status on the same inspection worksheet or a new one.

    Notes: Where the meter tube does not meet the specified requirements, the orifice meter run cannot be used in trade or custody transfer applications until it has been corrected and reverified.

B2.0 Thermometer wells

  1. Measure the distance between the thermometer well and the orifice plate as well as the distance between the thermometer well and the flow conditioner (if used), and record the measurements on the inspection worksheet.
  2. Refer to 4.9 of the report (1985) for the required location of the thermometer well.
  3. Record the conformance status (i.e. accepted or rejected) of the thermometer well on the inspection worksheet.
  4. Where the thermometer well does not meet the requirements of AGA Report No. 3, second edition, 1985, the contractor's representative may make any necessary adjustments. Repeat all required measurements in accordance with this section and record the "as left" data and conformance status on the same inspection worksheet or a new one.

    Notes: Where the thermometer well does not meet the specified requirements, the orifice meter run cannot be used in trade or custody transfer applications until it has been corrected and reverified.

B3.0 Orifice meter tube

This section applies to the orifice meter tube, which includes the straight pipe of the same diameter preceding (upstream) and following (downstream) the orifice plate and the flow conditioner, where used.

B3.1 General

  1. Ensure there are no pipe connections within the specified upstream and downstream sections of the meter tube other than the following:
    • Pressure taps (as per 4.8 of the report, 1985); and
    • Thermometer wells (as per 4.9 of the report, 1985).
  2. Ensure that any weld within A or C and B is machined to meet the requirements specified in 4.3.2 of the report (1985).
  3. Ensure all flanges and flange attachments within the designated meter tube lengths meet the requirements specified in 4.3 of the report (1985).

B3.2 Orifice meter tube inside surface

  1. Using the tester, measure the surface roughness of the inside pipe walls upstream and downstream of the orifice plate, and record the measurements on the inspection worksheet.

    Notes: According to the figure selected in B1.0 (b), the following sections are subject to the measurements:

    • A or C;
    • B; and
    • Upstream of the flow straightener within section A'.
  2. Confirm that the inside pipe walls meet the requirements specified in 4.3.2 of the report (1985).
  3. Record the conformance status (i.e. accepted or rejected) of the inside surface of the meter tube on the inspection worksheet.
  4. Where the inside surface of the orifice meter tube does not meet the requirements of AGA Report No. 3, second edition, 1985, the contractor's representative may make any necessary adjustments. Repeat all required measurements in accordance with this section and record the "as left" data and conformance status on the same inspection worksheet or a new one.

    Notes: Where the inside surface of the orifice meter tube does meet the specified requirements, the orifice meter run cannot be used in trade or custody transfer applications until it has been corrected and reverified.

B3.3 Orifice meter tube inside diameter ( D )

  1. Measure the inside diameter of the upstream and downstream sections of the meter tube as per 4.3.3 and 4.3.4 of the report (1985), and record the measurements on the inspection worksheet.

    Notes:

    • According to the figure selected in B1.0 (b), the following sections are subject to the measurements and no meter tube diameter measurements are required beyond these:
      • A or C;
      • B; and
      • Upstream of the straightening vanes within section A'.
    • The report (1985) permits inside diameter measurements upstream of the straightening vane, but they are seldom performed.
    • When a meter tube is made up of more than one part, such as a pipe, a flange and a fitting, the second and third diameter measurements should be made in the different parts or equivalent.
    • It is recommended to measure the diameter at the worst conditions within the tube (often at a weld or where the pipe is out-of-round or damaged) to ensure uniformity of the inside surface of the pipe and fitting.
    • The most suitable device for measuring the inside diameter of tubes is a dial bore gauge, which can be slid down the tubes to thoroughly search for irregularities such as ridges and hollows in the tube. Inside micrometers can also be used; however, they are much slower and less thorough, which can result in inaccurate inspection results.
  2. Compare the inside diameter measurements to the tolerances prescribed in 4.3.4 and 4.3.5 of the report (1985).
  3. If the inside diameter measurements do not meet the tolerances prescribed in 4.3.4 and 4.3.5 of the report (1985) for the maximum allowable β prescribed in PS-G-19, refer to the appropriate graph in the report (1985) to determine what β will allow a tolerance equal to or greater than the actual measurements.
  4. Ensure the lowest β meets the minimum allowable β prescribed in PS-G-19 and record it on the inspection worksheet.
  5. Record the conformance status (i.e. accepted, accepted with a restricted β or rejected) of the inside diameter of the orifice meter tube on the inspection worksheet.
  6. Where β does not meet the requirements of PS-G-19, the contractor's representative may make any necessary adjustments. Repeat all required measurements in accordance with this section and record the "as left" data and conformance status on the same inspection worksheet or a new one.

    Notes: Where the meter tube inside diameter does not meet the specified requirements, the orifice meter run cannot be used in trade or custody transfer applications until it has been corrected and reverified.

B4.0 Straightening vanes (where applicable)

  1. Examine the straightening vane and assess its conformity with the requirements specified in 4.5 of the report (1985) and PS-G-19.
  2. Ensure the straightening vane fits in the meter tube by installing it at its proper location.
  3. Record any nonconformity on the inspection worksheet.

B5.0 Orifice flanges (where applicable)

  1. Examine the orifice flanges and assess their conformity with the requirements specified in 4.6 of the report (1985).
  2. Record any nonconformity or β reduction on the inspection worksheet.

B6.0 Orifice fittings (where applicable)

  1. Ensure the orifice fitting is approved by MC.
  2. Examine the orifice fitting and assess its conformity with the requirements specified in 4.7 of the report (1985), PS-G-19 and the device's notice of approval.
  3. Record any nonconformity on the inspection worksheet.

B7.0 Pressure tap holes

B7.1 Pressure tap hole drilling and edges

Ensure the drilling and edges of pressure tap holes meet the requirements specified in 4.8.3, 4.8.5 and 4.8.6 of the report (1985).

B7.2 Pressure tap hole locations

  1. Measure the distance from the centreline of the tap hole to the orifice plate surface, both upstream and downstream, and record the measurements on the inspection worksheet.
  2. Compare the measurements to the tolerances prescribed in 4.8.1 or 4.8.2 of the report (1985).
  3. If the measurements of the pressure tap holes do not meet the tolerances prescribed in 4.8.1 or 4.8.2 of the report (1985) for the maximum allowable β prescribed in PS-G-19, refer to Figure 10 in the report to determine what β will allow a tolerance equal to or greater than the actual measurements.
  4. Ensure this lowest β meets the requirements for the minimum allowable β prescribed in PS-G-19 and record it on the inspection worksheet.
  5. Record the conformance status (i.e. accepted, accepted with a restricted β or rejected) of the pressure tap hole locations on the inspection worksheet.
  6. Where pressure tap hole locations do not meet the requirements of the report (1985), the contractor's representative may make any necessary adjustments. Repeat all required measurements in accordance with this section and record the "as left" data and conformance status on the same inspection worksheet or a new one.

    Notes: Where pressure tap hole locations do not meet the specified requirements, the orifice meter run cannot be used in trade or custody transfer applications until it has been corrected and reverified.

B7.3 Pressure tap hole diameters

  1. Measure the diameter of the pressure tap holes on the inner surface of the pipe at the locations indicated on the inspection worksheet and record the measurements on the worksheet.
  2. Compare the measurements to the tolerances prescribed in 4.8.4 of the report (1985).
  3. Record the conformance status (i.e. accepted or rejected) of the pressure tap hole diameters on the inspection worksheet.
  4. Where pressure tap hole diameters do not meet the requirements of the report (1985), the contractor's representative may make any necessary adjustments. Repeat all required measurements in accordance with this section and record the "as left" data and conformance status on the same inspection worksheet or a new one.

    Notes: Where pressure tap hole diameters do not meet the specified requirements, the orifice meter run cannot be used in trade or custody transfer applications until it has been corrected and reverified.

B8.0 Orifice plates

This section applies to all orifice plates at the metering station.

B8.1 Installation of an orifice plate within the meter tube

B8.1.1 Concentricity
  1. Measure the dimensions of the orifice plate as required on the dimension sketch of the inspection worksheet and record the measurements on the worksheet.
  2. Ensure the orifice plate is concentric with the inside diameter of the meter tube or orifice fitting within the tolerance prescribed in 4.2.4 of the report (1985) by calculating the eccentricity parallel to the vertical and horizontal axes.
  3. Record the conformance status (i.e. accepted, rejected) of the orifice plate concentricity on the inspection worksheet.
  4. Where the orifice plate is not concentric with the inside diameter of the meter tube or orifice fitting, the contractor's representative may make any necessary adjustments. Repeat all required measurements in accordance with this section and record the "as left" and conformance status on the same inspection worksheet or a new one.

    Notes: Where the orifice plate is not concentric, the orifice meter run cannot be used in trade or custody transfer applications until it has been corrected and reverified.

B8.1.2 Perpendicularity
  1. When the orifice plate is in position within the meter tube, measure the distance (depth) from the downstream orifice plate face to some reference point further downstream and record the measurements on the inspection worksheet.
  2. Ensure the orifice plate is perpendicular to the axis of the pipe as per 4.2.2 of the report (1985) by calculating the deviations from the vertical and horizontal axes.
  3. Record the conformance status (i.e. accepted or rejected) of the orifice plate perpendicularity on the inspection worksheet.
  4. Where the orifice plate is not perpendicular to the axis of the pipe when in position between the orifice flanges or in the orifice fitting, the contractor's representative may make any necessary adjustments. Repeat all required measurements in accordance with this section and record the "as left" conformance status on the same inspection worksheet or a new one.

    Notes: Where the orifice plate is not perpendicular, the orifice meter run cannot be used in trade or custody transfer applications until it has been corrected and reverified.

B8.2 Orifice plate faces

B8.2.1 Orifice plate surface roughness
  1. Using the tester, measure the surface roughness of the orifice plate at three sections and record the measurements on the inspection worksheet.
  2. Compare the measurements to the tolerances prescribed in 4.2.1 of the report (1985).
  3. Record the conformance status (i.e. accepted or rejected) on the surface roughness of the orifice plate on the inspection worksheet.
  4. Where applicable, cancel any verification stamp to indicate the rejection of the orifice plate.

    Notes: Where the orifice plate surface roughness does not meet the specified requirements, the orifice plate cannot be used in trade or custody transfer applications.

B8.2.2 Orifice plate flatness
  1. Measure the flatness of the orifice plate as per Figure 2 of the report (1985) and record the measurement on the inspection worksheet.
  2. Compare the measurement to the tolerances prescribed in 4.2.2 of the report (1985).
  3. Record the conformance status (i.e. accepted or rejected) of the flatness of the orifice plate on the inspection worksheet.
  4. Where applicable, cancel any verification stamp to indicate the rejection of the orifice plate.

    Notes: Where the orifice plate flatness does not meet the specified requirements, the orifice plate cannot be used in trade or custody transfer applications.

B8.3 Orifice plate bore edge

  1. Evaluate the sharpness of the square edge of the orifice plate bore by running a finger nail around the upstream edge to detect any irregularities. Ensure the upstream edge is square and sharp.

    Notes:

    • The edge must not reflect light when viewed without magnification, as per 4.2.3 of the report (1985).
    • If a nick can be felt with a fingernail, it can usually be seen in a good light, such as sunlight.
  2. Record the conformance status (i.e. accepted or rejected) of the sharpness of the orifice bore edge on the inspection worksheet.
  3. Where applicable, cancel any verification stamp to indicate the rejection of the orifice plate.

    Notes: Where the orifice plate bore edge does not meet the specified requirements, the orifice plate cannot be used in trade or custody transfer applications.

B8.4 Orifice edge thickness ( e )

  1. Measure the orifice edge thickness ( e ) as required on the dimension sketch of the inspection worksheet and record it.
  2. Compare the measured e to the requirements specified in 4.2.1 of the report (1985).
  3. Record the conformance status (i.e. accepted or rejected) of the orifice edge thickness on the inspection worksheet.
  4. Where applicable, cancel any verification stamp to indicate the rejection of the orifice plate.

    Notes: Where the orifice edge thickness does not meet the specified requirements, the orifice plate cannot be used in trade or custody transfer applications.

B8.5 Orifice plate thickness ( E )

  1. Measure the orifice plate thickness ( E ) as required on the dimension sketch of the inspection worksheet and record it.
  2. Compare the measured E to the requirements specified in 4.2.1 of the report (1985).
  3. Record the conformance status (i.e. accepted or rejected) of the orifice plate thickness on the inspection worksheet.
  4. Where applicable, cancel any verification stamp to indicate the rejection of the orifice plate.

    Notes: Where the orifice plate thickness does not meet the specified requirements, the orifice plate cannot be used in trade or custody transfer applications.

B8.6 Orifice plate bore diameter ( d )

  1. Ensure the β stamped on the plate is within the range prescribed in PS-G-19 and record it on the inspection worksheet.
  2. Measure the following dimensions as required on the dimension sketch of the inspection worksheet and record them on the worksheet:
    • Actual bore diameter ( d ) at four different diameters, evenly spaced; and
    • Diameter of the finished area on the plate ( D ).
  3. Compare the measurements to the tolerances in Figure 1 and Table 1 of the report (1985).
  4. Record the conformance status (i.e. accepted or rejected) of the orifice plate bore diameter on the inspection worksheet.

    Notes: Where the orifice plate bore diameter is greater than that permitted by a reduced β or does not fully meet the specified requirements, the orifice plate cannot be used in trade or custody transfer applications.

  5. Where applicable, cancel any verification stamp to indicate the rejection of the orifice plate.

B8.7 Orifice plate bevel (Ɵ)

  1. Measure the orifice plate bevel angle (Ɵ) as required on the dimension sketch of the inspection worksheet and record it on the worksheet.
  2. Compare the measured Ɵ to the requirements specified in 4.2.1 of the report (1985).
  3. Record the conformance status (i.e. accepted or rejected) of the orifice plate bevel angle on the inspection worksheet.
  4. Where applicable, cancel any verification stamp to indicate the rejection of the orifice plate.

    Notes: Where the orifice plate bevel angle does not meet the specified requirements, the orifice plate cannot be used in trade or custody transfer applications.

Appendix C—Verifications and reverifications of primary elements in accordance with American Gas Association Report No. 3, Part 2, fourth edition, 2000

C1.0 Orifice meter run configuration

  1. Confirm that the meter run is installed either horizontally or vertically (with the gas flowing downward).
  2. Measure the following linear dimensions of the orifice meter tube as required on the dimension sketch of the inspection worksheet and record them on the worksheet:
    • Overall upstream tube length (UL);
    • Overall downstream tube length (DL);
    • Upstream tube length from the orifice plate to the downstream end of the flow straightener or isolating flow conditioner, if either is used (UL2); and
    • Upstream tube length from the downstream end of the flow straightener or isolating flow conditioner to the extreme upstream end of the orifice meter tube (UL1).
  3. Refer to tables 2-7 and 2-8 in 2.6.3 of the report (2000) to determine if the measured dimensions meet the minimum length requirements for the maximum allowable diameter ratio (βr) prescribed in PS-G-19.

    Notes: If a flow conditioner is used, ensure that it meets the minimum length requirements. There is no provision for βr reduction with this device, so if the minimum length requirements are not met, the orifice meter is rejected.

  4. If the measured dimensions do not meet the minimum length requirements for the maximum allowable βr prescribed in PS-G-19, refer to tables 2-7 and 2-8 in the report (2000) to determine which tube length restricts the βr the most.

    Notes: As βr decreases, the tube length requirements decrease.

  5. Ensure this lowest βr meets the requirements for the minimum allowable βr prescribed in PS-G-19 and record it on the inspection worksheet.
  6. Record the conformance status (i.e. accepted, accepted with a restricted βr or rejected) of the orifice meter tube on the inspection worksheet.
  7. Where βr does not meet the requirements of PS-G-19, the contractor's representative may make any necessary adjustments. Repeat all required measurements in accordance with this section and record "as left" data and the conformance status on the same inspection worksheet or a new one.

    Notes: Where the meter tube does not meet the specified requirements, the orifice meter run cannot be used in trade or custody transfer applications until it has been corrected and reverified.

C2.0 Thermometer wells

  1. Measure the distance between the thermometer well and the orifice plate as well as the distance between thermometer well and the flow conditioner (if used), and record the measurements on the inspection worksheet.
  2. Refer to 2.6.5 in the report (2000) for the required location of the thermometer well.
  3. Record the conformance status (i.e. accepted or rejected) of the thermometer well on the inspection worksheet.
  4. Where the thermometer well does not meet the requirements of the report (2000), the contractor's representative may make any necessary adjustments. Repeat all required measurements in accordance with this section and record the "as left" data and conformance status on the same inspection worksheet or a new one.

    Notes: Where the thermometer well does not meet the specified requirements, the orifice meter run cannot be used in trade or custody transfer applications until it has been corrected and reverified.

C3.0 Orifice meter tube

This section applies to the orifice meter tube, which includes the straight pipe of the same diameter preceding (upstream) and following (downstream) the orifice plate and the flow conditioner, where used.

C3.1 General

  1. Ensure there are no pipe connections within the specified upstream and downstream sections of the meter tube other than the following:
    • Pressure taps (as specified in 2.5.4 of the report);
    • Temperature probes (as specified in 2.6.5 of the report);
    • Flow conditioner attachments (either flanged or in-line);
    • Orifice plate holders (as specified in 2.5.3.2 of the report); and
    • In-line meter tube flanges necessary to connect sections of the meter tube.
  2. Ensure that any weld downstream from the face of the orifice plate is within 2" or 0.5 D is machined to meet requirements specified in 2.5.1.3.2 and 2.5.1.1 of the report (2000) respectively.
  3. For any downstream flange connection within 2" or 0.5 D , ensure the gasket does not protrude into the meter tube.
  4. Ensure that a flange on the upstream side of the orifice plate is, as a minimum, no closer than the designated flow conditioner location or 10 Di for meter tubes without flow conditioners (not including flanged fittings specified in the report, 2000).
  5. Ensure all flanges and flange attachments within the designated meter tube lengths meet all requirements specified in 2.5.1 of the report (2000).

C3.2 Orifice meter tube inside surface

  1. Using the tester, measure the surface roughness of the inside pipe walls as per 2.5.1.1 of the report (2000), and record the measurement on the inspection worksheet.

    Notes: According to Figure 2-6 of the report (2000), the following meter tube sections are subject to the measurements:

    • UL or UL2;
    • DL;
    • Upstream of the flow straightener within section UL1; and
    • Upstream of UL or UL1 or 17 Di , whichever is less.
  2. Confirm that the inside pipe walls comply with the requirements specified in 2.5.1.1 of the report (2000).
  3. Record the conformance status (i.e. accepted or rejected) of the inside surface of the orifice meter tube on the inspection worksheet.
  4. Where the inside surface of the orifice meter tube does not meet the requirements of the report (2000), the contractor's representative may make any necessary adjustments. Repeat all required measurements in accordance with this section and record the "as left" data and conformance status on the same inspection worksheet or a new one.

    Notes: Where the inside surface of the orifice meter tube does not meet the specified requirements, the orifice meter run cannot be used in trade or custody transfer applications until it has been corrected and reverified.

C3.3 Orifice meter tube diameter ( Dm , Dr )

  1. Ensure the meter tube is under thermally stable conditions, measure the meter tube temperature ( Tm ) with a certified thermometer and record the Tm to the nearest degree Fahrenheit (0.5° C) on the inspection worksheet.

    Notes: Thermally stable conditions mean that the temperature is constant within 5° F (2.5° C) at time of internal diameter measurements.

  2. Measure the internal diameter of the meter tube as per 2.5.1.2 of the report (2000) and record all measurements on the inspection worksheet.

    Notes:

    • According to Figure 2-6 of the report (2000), the following sections are subject to the measurements and no meter tube diameter measurements are required beyond these:
      • UL or UL2;
      • DL; and
      • Upstream of the flow straightener within section UL1.
    • The report (2000) permits internal diameter measurements upstream of the flow straightener, but they are seldom performed.
    • When a meter tube is made up of more than one part, such as a pipe, a flange and a fitting, the second and third diameter measurements should be made in the different parts or equivalent.
    • It is recommended to take the diameter measurements at the worst conditions within the tube (often at a weld or where the pipe is out-of-round or damaged) to ensure uniformity of the inside surface of the pipe and fitting.
    • The most suitable device for measuring internal diameters is a dial bore gauge, which can be slid down the tube to thoroughly search for irregularities such as ridges and hollows in the tube. Inside micrometers can also be used; however, they are much slower and less thorough, which can result in inaccurate inspection results.
  3. Compare the internal diameter measurements to the tolerances prescribed in 2.5.1.3 of the report (2000).
  4. Record the conformance status (i.e. accepted or rejected) of the measured internal diameter of the meter tube ( Dm ) on the inspection worksheet.
  5. Where the internal diameter measurements do not meet the requirements of the report (2000), the contractor's representative may make any necessary adjustments. Repeat all required measurements in accordance with this section and record the "as left" data and conformance status on the same inspection worksheet or a new one.

    Notes: Where the meter tube internal diameter does not meet the specified requirements, the orifice meter run cannot be used in trade or custody transfer applications until it has been corrected and reverified.

C3.4 Orifice plate gasket or sealing device recesses and protrusions

  1. Examine the orifice plate gasket or sealing device and assess its conformity with the requirements specified in 2.5.1.4 of the report (2000).
  2. Record any nonconformity on the inspection worksheet.

C4.0 Flow straightener (where applicable)

  1. Examine the 1998 Uniform Concentric 19-tube bundle flow straightener and assess its conformity with the requirements specified in 2.5.5.1, 2.5.5.2 and 2.5.5.3 of the report (2000) and PS-G-19.
  2. Record any nonconformity on the inspection worksheet.

C5.0 Orifice flanges (where applicable)

  1. Examine the orifice flanges and assess their conformity with the requirements specified in 2.5.2 of the report (2000).
  2. Record any nonconformity or restricted βr on the inspection worksheet.

C6.0 Orifice fittings (where applicable)

  1. Ensure the orifice fitting is approved by MC.
  2. Examine the orifice fitting and assess its conformity with the requirements specified in 2.5.3 of the report (2000), PS-G-19 and the device's notice of approval.
  3. Record any nonconformity on the inspection worksheet.

C7.0 Pressure taps

C7.1 Pressure tap hole drilling and edges

Ensure the drilling and edges of pressure tap holes meet the requirements specified in 2.5.4.2 and 2.5.4.4 of the report (2000).

C7.2 Pressure tap hole locations

  1. Measure the distance from the centreline of the tap holes to the orifice plate surface, both upstream and downstream, and record the measurements on the inspection worksheet.
  2. Compare the measurements to the tolerances prescribed in 2.5.4.1 of the report (2000).
  3. If the measurements do not meet the tolerances prescribed in 2.5.4.1 of the report (2000) for the maximum allowable βr prescribed in PS-G-19, refer to Figure 2-3 in the report to determine what βr will allow a tolerance equal to or greater than the actual measurements.
  4. Ensure this lowest βr meets the requirements for the minimum allowable βr prescribed in PS-G-19 and record it on the inspection worksheet.
  5. Record the conformance status (i.e. accepted, accepted with a restricted βr or rejected) of pressure tap hole locations on the inspection worksheet.
  6. Where pressure tap hole locations do not meet the requirements of the report (2000), the contractor's representative may make any necessary adjustments. Repeat all required measurements in accordance with this section and record the "as left" data and conformance status on the same inspection worksheet or a new one.

    Notes: Where pressure tap holes do not meet the specified requirements, the orifice meter run cannot be used in trade or custody transfer applications until it has been corrected and reverified.

C7.3 Pressure tap hole diameter and length of gauge lines

  1. Ensure gauge lines are only used for measuring differential and/or static pressure.
  2. Measure the diameter of the pressure tap holes on the inner surface of the pipe in the different locations indicated on the inspection worksheet and record the measurements on the inspection worksheet.
  3. Compare the measurements to the tolerances prescribed in 2.5.4.3 of the report (2000).
  4. Record the conformance status (i.e. accepted or rejected) of pressure tap hole diameters on the inspection worksheet.
  5. Where pressure tap hole diameters do not meet the requirements of the report (2000), the contractor's representative may make any necessary adjustments. Repeat all required measurements in accordance with this section and record the "as left" data and conformance status on the same inspection worksheet or a new one.

    Notes: Where pressure tap holes do not meet the specified requirements, the orifice meter run cannot be used in trade or custody transfer applications until it has been corrected and reverified.

C8.0 Orifice plates

This section applies to all orifice plates at the metering station.

C8.1 Installation of an orifice plate within the meter tube

C8.1.1 Eccentricity (Ɛ)
  1. Measure the dimensions of the orifice plate as required on the dimension sketch of the inspection worksheet and record the measurements on the worksheet.
  2. Ensure the orifice plate is concentric with both the upstream and the downstream inside bore of the orifice plate holder within the tolerances prescribed in 2.6.2.1 of the report (2000) by calculating the eccentricity parallel to the vertical and horizontal axes.
  3. Where the orifice plate eccentricity within the meter tube does not meet the tolerances prescribed in 2.6.2.1 of the report (2000) for the maximum allowable βr prescribed in PS‑G-19, refer to Figure 2-6 in the report to determine what βr will allow a tolerance equal to, or greater than, the actual eccentricity measurements.
  4. Ensure this lowest βr meets the minimum allowable βr prescribed in PS-G-19 and record it on the inspection worksheet.
  5. Record the conformance status (i.e. accepted, accepted with a restricted βr or rejected) of the orifice plate eccentricity within the meter tube on the inspection worksheet.
  6. Where the orifice plate is not concentric with both the upstream and the downstream inside bore of the orifice plate holder, the contractor's representative may make any necessary adjustments. Repeat all required measurements in accordance with this section and record the "as left" measurements and conformance status on the same inspection worksheet or a new one.

    Notes: Where the orifice plate is not concentric, the orifice meter run cannot be used in trade or custody transfer applications until it has been corrected and reverified.

C8.1.2 Perpendicularity
  1. When the orifice plate is in position within the meter tube, measure the distance (depth) from the downstream orifice plate face to a reference point further downstream and record the measurement on the inspection worksheet.
  2. Ensure the orifice plate is perpendicular to the axis of the pipe as per 2.6.2.2 of the report (2000) by calculating the deviations from the vertical and horizontal axes.
  3. Record the conformance status (i.e. accepted or rejected) of the orifice plate perpendicularity on the inspection worksheet.
  4. Where the orifice plate is not perpendicular to the axis of the pipe when in position between the orifice flanges or in the orifice fitting, the contractor's representative may make any necessary adjustments. Repeat all required measurements in accordance with this section and record the "as left" data and conformance status on the same inspection worksheet or a new one.

    Notes: Where the orifice plate is not perpendicular, the orifice meter run cannot be used in trade or custody transfer applications until it has been corrected and reverified.

C8.2 Orifice plate faces

C8.2.1 Orifice plate surface roughness
  1. Using the tester, measure the surface roughness of the orifice plate at three sections and record the measurements on the inspection worksheet.
  2. Compare the measurements to the tolerances prescribed in 2.4.1 of the report (2000).
  3. Record the conformance status (i.e. accepted or rejected) of the surface roughness of the orifice plate on the inspection worksheet.
  4. Where applicable, cancel any verification stamp to indicate the rejection of the orifice plate.

    Notes: Where the orifice plate surface roughness does not meet the specified requirements, the orifice plate cannot be used in trade or custody transfer applications.

C8.2.2 Orifice plate flatness
  1. Measure the flatness of the orifice plate as per Figure 2-2a, 2-2b or 2-2c of the report (2000) and record the measurement on the inspection worksheet.
  2. Compare the measurement to the tolerances prescribed in 2.4.1 of the report (2000).
  3. Record the conformance status (i.e. accepted or rejected) of the flatness of the orifice plate on the inspection worksheet.
  4. Where applicable, cancel any verification stamp to indicate the rejection of the orifice plate.

    Notes: Where the orifice plate flatness does not meet the specified requirements, the orifice plate cannot be used in trade or custody transfer applications.

C8.3 Orifice plate bore edge

  1. Evaluate the sharpness of the square edge of the orifice plate bore by running a finger nail around the upstream edge to detect any irregularities. Ensure the upstream edge is square and sharp.

    Notes:

    • The edge must not reflect light when viewed without magnification, as per section 2.4.2 of the report (2000).
    • If a nick can be felt with a fingernail, it can usually be seen in a good light, such as sunlight.
  2. Record the conformance status (i.e. accepted or rejected) of the sharpness of the orifice plate bore edge on the inspection worksheet.
  3. Where applicable, cancel any verification stamp to indicate the rejection of the orifice plate.

    Notes: Where the orifice plate bore edge does not meet the specified requirements, the orifice plate cannot be used in trade or custody transfer applications.

C8.4 Orifice plate bore diameter ( dm , dr ) and roundness

  1. Ensure the orifice plate is under thermally stable conditions, measure the temperature ( Tm ) of the orifice plate with a certified thermometer and record the Tm to the nearest degree Fahrenheit (0.5 °C) on the inspection worksheet.

    Notes: Thermally stable conditions mean that the temperature is constant within 1 °F (0.5 °C) at time of diameter measurements.

  2. Measure the following dimensions as required on the dimension sketch of the inspection worksheet and record them on the worksheet:
    • Actual bore diameter ( dm ) at four different diameters, evenly spaced; and
    • Diameter of the finished area on the plate ( Dm ).
  3. Compare the dm to the requirements specified in 2.4.3 and Table 2-1 of the report (2000).
  4. Record the conformance status (i.e. accepted or rejected) of the orifice plate bore diameter and roundness on the inspection worksheet.

    Notes: Where the orifice plate bore diameter is greater than that permitted by a reduced βr, the orifice plate cannot be used in trade or custody transfer applications.

  5. Where applicable, cancel any verification stamp to indicate the rejection of the orifice plate.

C8.5 Orifice plate bore thickness ( e )

  1. Ensure the orifice plate is under thermally stable conditions, measure the temperature ( Tm ) of the orifice plate with a certified thermometer and record the Tm to the nearest degree Fahrenheit (0.5 °C) on the inspection worksheet.

    Notes: Thermally stable conditions means that the temperature is constant within 1 °F (0.5 °C) at time of diameter measurements.

  2. Measure the orifice plate bore thickness ( e ) as required on the dimension sketch of the inspection worksheet and record it.
  3. Compare the measured e to the requirements specified in section 2.4.4 of the report (2000).
  4. Record the conformance status (i.e. accepted or rejected) of the orifice plate bore thickness on the inspection worksheet.
  5. Where applicable, cancel any verification stamp to indicate the rejection of the orifice plate.

    Notes: Where the orifice plate bore thickness does not meet the specified requirements, the orifice plate cannot be used in trade or custody transfer applications.

C8.6 Orifice plate thickness ( E )

  1. Ensure the orifice plate is under thermally stable conditions, measure the temperature ( Tm ) of the orifice plate with a certified thermometer and record the Tm to the nearest degree Fahrenheit (0.5 °C) on the inspection worksheet.

    Notes: Thermally stable conditions mean that the temperature is constant within 1 °F (0.5 °C) at time of diameter measurements.

  2. Measure the orifice plate thickness ( E ) as required on the dimension sketch of the inspection worksheet and record it.
  3. Compare the measured E to the requirements specified in 2.4.5 and Table 2-3 of the report (2000).
  4. Record the conformance status (i.e. accepted or rejected) of the orifice plate thickness on the inspection worksheet.
  5. Where applicable, cancel any verification stamp to indicate the rejection of the orifice plate.

    Notes: Where the orifice plate thickness does not meet the specified requirements, the orifice plate cannot be used in trade or custody transfer applications.

C8.7 Orifice plate bevel (Ɵ)

  1. Ensure the orifice plate is under thermally stable conditions, measure the temperature ( Tm ) of the orifice plate with a certified thermometer and record the measured Tm to the nearest degree Fahrenheit (0.5 °C) on the inspection worksheet.

    Notes: Thermally stable conditions mean that the temperature is constant within 1 °F (0.5 °C) at time of diameter measurements.

  2. Measure the orifice plate bevel angle (Ɵ) as required on the dimension sketch of the inspection worksheet and record it.
  3. Compare the measured Ɵ to the requirements specified in 2.4.6 and Table 2-3 of the report (2000).
  4. Record the conformance status (i.e. accepted or rejected) of the orifice plate bevel angle on the inspection worksheet.
  5. Where applicable, cancel any verification stamp to indicate the rejection of the orifice plate.

    Notes: Where the orifice plate bevel angle does not meet the specified requirements, the orifice plate cannot be used in trade or custody transfer applications.

Appendix D—Verifications and reverifications of primary elements in accordance with American Gas Association Report No. 3, Part 2, fifth edition, 2016

D1.0 Orifice meter run configuration

  1. Confirm that the meter run is installed either horizontally or vertically (with the gas flowing downward).
  2. Measure the following linear dimensions of the orifice meter tube as required on the dimension sketch of the inspection worksheet and record them on the worksheet:
    • Overall upstream tube length (UL);
    • Overall downstream tube length (DL);
    • Upstream tube length from the orifice plate to the downstream end of the flow straightener or isolating flow conditioner, if either is used (UL2); and
    • Upstream tube length from the downstream end of the flow straightener or flow conditioner to the extreme upstream end of the orifice meter tube (UL1).
  3. Refer to tables 7, 8a and 8b in section 6.3 of the report (2016) to determine if the measured dimensions meet the minimum length requirements for the maximum allowable diameter ratio (βr) prescribed in PS-G-19.

    Notes: If a flow conditioner is used, ensure that it meets the minimum length requirements. There is no provision for βr reduction with this device, so if the minimum length requirements are not met, the orifice meter is rejected.

  4. If the measured dimensions do not meet the minimum length requirements for the maximum allowable βr prescribed in PS-G-19, refer to tables 7, 8a and 8b in the report (2016), to determine which tube length restricts the βr the most.

    Notes: As βr decreases, the tube length requirements decrease.

  5. Ensure this lowest βr meets the requirements for the minimum allowable βr prescribed in PS-G-19 and record it on the inspection worksheet.
  6. Record the conformance status (i.e. accepted, accepted with a restricted βror rejected) of the orifice meter tube.
  7. Where βr does not meet the requirements of PS-G-19, the contractor's representative may make any necessary adjustments. Repeat all required measurements in accordance with this section and record the "as left" data and the conformance status on the same inspection worksheet or a new one.

    Notes: Where the meter tube does not meet the specified requirements, the orifice meter run cannot be used in trade or custody transfer applications until it has been corrected and reverified.

D2.0 Thermometer wells

  1. Measure the distance between the thermometer well and the orifice plate and record it on the inspection worksheet.
  2. Measure the length of the thermometer well and record it on the inspection worksheet.
  3. Refer to 6.5 in the report (2016) for the required location and length of the thermometer well.
  4. Record the conformance status (i.e. accepted or rejected) of the thermometer well on the inspection worksheet.
  5. Where the thermometer well does not meet the requirements of the report (2016), the contractor's representative may make any necessary adjustments. Repeat all required measurements in accordance with this section and record the "as left" data and conformance status on the same inspection worksheet or a new one.

    Notes: Where the thermometer well does not meet the specified requirements, the orifice meter run cannot be used in trade or custody transfer applications until it has been corrected and reverified.

D3.0 Orifice meter tube

This section applies to the orifice meter tube, which includes the straight pipe of the same diameter preceding (upstream) and following (downstream) the orifice plate and the flow conditioner, where used.

D3.1 General

  1. Ensure there are no pipe connections within the specified upstream and downstream sections of the meter tube other than the following:
    • Pressure taps (as specified in 5.4 of the report);
    • Temperature probes (as specified in 6.5 of the report);
    • Flow conditioner attachments (either flanged or in-line);
    • Orifice plate holders (as specified in 5.3.2 of the report); and
    • In-line meter tube flanges necessary to connect sections of the meter tube.
  2. Ensure that any weld downstream from the face of the orifice plate within 2" or 0.5 D is machined to meet requirements specified in 5.1.3.2 and 5.1.1 of the report (2016) respectively.
  3. For any downstream flange connection within 2" or 0.5 D , ensure the gasket does not protrude into the meter tube.
  4. Ensure that a flange on the upstream side of the orifice plate is, as a minimum, no closer than the designated flow conditioner location or 10 Di for meter tubes without flow conditioners (not including flanged fittings specified in the report).
  5. Ensure all flanges and flange attachments within the designated meter tube lengths meet all requirements specified in 5.1 of the report (2016).

D3.2 Orifice meter tube inside surface

  1. Using the tester, measure the surface roughness of the inside pipe walls as per 5.1.1 the report (2016) and record the measurements on the inspection worksheet.

    Notes: According to Figure 6 of the report (2016), the following sections are subject to the measurements:

    • UL or UL2;
    • DL;
    • Upstream of the flow straightener within section UL1; and
    • Upstream of UL or UL1 or 17 Di , whichever is less.
  2. Confirm that the inside pipe walls meet the requirements specified in 5.1.1 of the report (2016).
  3. Record the conformance status (i.e. accepted or rejected) of the inside surface of the orifice meter tube on the inspection worksheet.
  4. Where the inside surface orifice meter tube does not meet the requirements of the report (2016), the contractor's representative may make any necessary adjustments. Repeat the all required measurements in accordance with this section and record the "as left" data and conformance status on the same inspection worksheet or a new one.

    Notes: Where the inside surface of the orifice meter tube does not meet the specified requirements, the orifice meter run cannot be used in trade or custody transfer applications until it has been corrected and reverified.

D3.3 Orifice meter tube diameter ( Dm , Dr )

  1. Ensure the meter tube is under thermally stable conditions, measure the meter tube temperature ( Tm ) with a certified thermometer and record the Tm to the nearest degree Fahrenheit (0.5° C) on the inspection worksheet.

    Notes: Thermally stable conditions mean that the temperature is constant within 5 °F (2.5 °C) at time of internal diameter measurements.

  2. Measure the internal diameter of the meter tube as per 5.1.2 of the report (2016) and record all measurements on the inspection worksheet.

    Notes:

    • According to Figure 6 of the report (2016), the following sections are subject to the measurements and no tube diameter measurements are required beyond these:
      • UL or UL2;
      • DL; and
      • Upstream of the flow straightener within section UL1.
    • The report (2016) permits internal diameter measurements upstream of the flow straightener, but they are seldom performed.
    • When a meter tube is made up of more than one part, such as a pipe, a flange and a fitting, the second and third diameter measurements should be made in the different parts or equivalent.
    • It is recommended to take the diameter measurements at the worst conditions within the tube (often at a weld or where the pipe is out-of-round or damaged) to ensure uniformity of the inside surface of the pipe and fitting.
    • The most suitable device for measuring internal diameters is a dial bore gauge, which can be slid down the tube to thoroughly search for irregularities such as ridges and hollows in the tube. Inside micrometers can also be used; however, they are much slower and less thorough, which can result in inaccurate inspection results.
  3. Compare the internal diameter measurements to the tolerances prescribed in 5.1.3 of the report (2016).
  4. Record the conformance status (i.e. accepted or rejected) of the measured internal diameter of the meter tube ( Dm ) on the inspection worksheet.
  5. Where the internal diameter measurements do not meet the requirements of the report (2016), the contractor's representative may make any necessary adjustments. Repeat all required measurements in accordance with this section and record the "as left" data and conformance status on the same inspection worksheet or a new one.

    Notes: Where the orifice meter tube diameter does not meet the specified requirements, the orifice meter run cannot be used in trade or custody transfer applications until it has been corrected and reverified.

D3.4 Orifice plate gasket or sealing device recesses and protrusions

  1. Examine the orifice plate gasket or sealing device and assess its conformity with the requirements specified in 5.1.4 of the report (2016).
  2. Record any nonconformity on the inspection worksheet.

D4.0 Flow straighteners (where applicable)

  1. Examine the 1998 Uniform Concentric 19-tube bundle flow straightener and assess its conformity with the requirements specified in 5.5.1 to 5.5.3 of the report (2016) and PS-G-19.
  2. Record any nonconformity on the inspection worksheet.

D5.0 Orifice flanges (where applicable)

  1. Examine the orifice flanges and assess their conformity with the requirements specified in 5.2 of the report (2016).
  2. Record any nonconformity or restricted βr on the inspection worksheet.

D6.0 Orifice fittings (where applicable)

  1. Ensure the orifice fitting is approved by MC.
  2. Examine the orifice fitting and assess its conformity with the requirements specified in 5.3 of the report (2016), PS-G-19 and the device's notice of approval.
  3. Record any nonconformity on the inspection worksheet.

D7.0 Pressure taps

D7.1 Pressure tap drilling and edges

Ensure the drilling and edges of pressure tap holes meet the requirements specified in 5.4.2 and 5.4.4 of the report (2016).

D7.2 Pressure tap hole locations

  1. Measure the distance from the centreline of the pressure tap holes to the orifice plate surface, both upstream and downstream, and record both measurements on the inspection worksheet.
  2. Compare the measurements to the tolerances prescribed in 5.4.1 of the report (2016).
  3. If the measurements do not meet the tolerances prescribed in 5.4.1 of the report (2016) for the maximum allowable βr prescribed in PS-G-19, refer to Figure 3 in the report to determine what βr will allow a tolerance equal to or greater than the actual measurements.
  4. Ensure this lowest βr meets the requirements for the minimum allowable βr prescribed in PS‑G-19 and record it on the inspection worksheet.
  5. Record the conformance status (i.e. accepted, accepted with a restricted βr or rejected) of pressure tap hole locations on the inspection worksheet.
  6. Where pressure tap holes locations do not meet the requirements of the report (2016), the contractor's representative may make any necessary adjustments. Repeat all required measurements in accordance with this section and record the "as left" data and conformance status on the same inspection worksheet or a new one.

    Notes: Where pressure tap holes locations do not meet the specified requirements, the orifice meter run cannot be used in trade or custody transfer applications until it has been corrected and reverified.

D7.3 Pressure tap hole diameter and length of gauge lines

  1. Ensure gauge lines are only used for measuring differential and/or static pressure.
  2. Measure the diameter of the pressure tap holes on the inner surface of the pipe and record the measurements on the inspection worksheet.
  3. Compare the measurements to the tolerances prescribed in 5.4.3 of the report (2016).
  4. Record the conformance status (i.e. accepted or rejected) of the pressure tap hole diameter on the inspection worksheet.
  5. Where the pressure tap hole diameter does not meet the requirements of the report (2016), the contractor's representative may make any necessary adjustments. Repeat all required measurements in accordance with this section and record the "as left" data and conformance status on the same inspection worksheet or a new one.

    Notes: Where pressure tap holes do not meet the specified requirements, the orifice meter run cannot be used in trade or custody transfer applications for custody transfer or trade purposes until it has been corrected and reverified.

D8.0 Orifice plates

This section is applicable to all orifice plates at the metering station.

D8.1 Installation of an orifice plate within the meter tube

D8.1.1 Eccentricity (Ɛ)
  1. Measure the dimensions of the orifice plate as required on the dimension sketch of the inspection worksheet and record the measurements on the worksheet.
  2. Ensure the orifice plate is concentric with both the upstream and the downstream inside bore of the orifice plate holder within the tolerances prescribed in 6.2.1 of the report (2016) by calculating the eccentricity parallel to the vertical and horizontal axes.
  3. Where the orifice plate eccentricity within the meter tube does not meet the tolerances prescribed in 6.2.1 of the report (2016) for the maximum allowable βr prescribed in PS-G-19, refer to Figure 6 in the report to determine what βr will allow a tolerance equal to, or greater than, the actual eccentricity measurements.
  4. Ensure this lowest βr meets the minimum allowable βr prescribed in PS-G-19 and record it on the inspection worksheet.
  5. Record the conformance status (i.e. accepted, accepted with a restricted βr or rejected) of the orifice plate eccentricity within the meter tube on the inspection worksheet.
  6. Where the orifice plate is not concentric with both the upstream and the downstream inside bore of the orifice plate holder, the contractor's representative may make any necessary adjustments. Repeat all required measurements in accordance with this section and record the "as left" data and conformance status on the same inspection worksheet or a new one.

    Notes: Where the orifice plate is not concentric, the orifice meter run cannot be used in trade or custody transfer applications until it has been corrected and reverified.

D8.1.2 Perpendicularity
  1. When the orifice plate is in position within the meter tube, measure the distance (depth) from the downstream orifice plate face to a reference point further downstream and record the measurement on the inspection worksheet.
  2. Ensure the orifice plate is perpendicular to the axis of the pipe as per 6.2.2 of the report (2016) by calculating the deviations from the vertical and horizontal axes.
  3. Record the conformance status (i.e. accepted or rejected) of the orifice plate perpendicularity on the inspection worksheet.
  4. Where the orifice plate is not perpendicular to the axis of the pipe, when in position between the orifice flanges or in the orifice fitting, the contractor's representative may make any necessary adjustments. Repeat all required measurements in accordance with this section and record the "as left" measurements and conformance status on the same inspection worksheet or a new one.

    Notes: Where the orifice plate is not perpendicular, the orifice meter run cannot be used in trade or custody transfer applications until it has been corrected and reverified.

D8.2 Orifice plate faces

D8.2.1 Orifice plate surface roughness
  1. Using the tester, measure the surface roughness of the orifice plate at 3 sections and record the measurements on the inspection worksheet.
  2. Compare the measured roughness to the tolerances prescribed in 4.2 of the report (2016).
  3. Record the conformance status (i.e. accepted or rejected) of the surface roughness of the orifice plate on the inspection worksheet.
  4. Where applicable, cancel any verification stamp to indicate the rejection of the orifice plate.

    Notes: Where the orifice plate surface roughness does not meet the specified requirements, the orifice plate cannot be used in trade or custody transfer applications.

D8.2.2 Orifice plate flatness
  1. Measure the flatness of the orifice plate as per figure 2a, 2b or 2c in the report (2016) and record the measurement on the inspection worksheet.
  2. Compare the measured flatness to the tolerances prescribed in 4.2 of the report (2016).
  3. Record the conformance status (i.e. accepted or rejected) of the flatness of the orifice plate on the inspection worksheet.
  4. Where applicable, cancel any verification stamp to indicate the rejection of the orifice plate.

    Notes: Where the orifice plate flatness does not meet the specified requirements, the orifice plate cannot be used in trade or custody transfer applications.

D8.3 Orifice plate bore edge

  1. Evaluate the sharpness of the square edge of the orifice plate bore by running a finger nail around the upstream edge to detect any irregularities. Ensure the upstream edge is square and sharp.

    Notes:

    • The edge must not reflect light when viewed without magnification, as per section 4.3 of the report (2016).
    • If a nick can be felt with a fingernail, it can usually be seen in a good light, such as sunlight.
  2. Record the conformance status (i.e. accepted or rejected) of the sharpness of the orifice plate bore edge on the inspection worksheet.
  3. Where applicable, cancel any verification stamp to indicate the rejection of the orifice plate.

    Notes: Where the orifice plate bore edge does not meet the specified requirements, the orifice plate cannot be used in trade or custody transfer applications.

D8.4 Orifice plate bore diameter ( dm , dr ) and roundness

  1. Ensure the orifice plate is under thermally stable conditions, measure the temperature ( Tm ) of the orifice plate with a certified thermometer and record the Tm to the nearest degree Fahrenheit (0.5 °C) on the inspection worksheet.

    Notes: Thermally stable conditions mean that the temperature is constant within 1 °F (0.5 °C) at time of diameter measurements.

  2. Measure the following dimensions as required on the dimension sketch of the inspection worksheet and record them on the worksheet:
    • Actual bore diameter ( dm ) at four different diameters, evenly spaced; and
    • Diameter of the finished area on the plate ( Dm ).
  3. Compare the dm to the requirements specified in 4.4 and Table 1 of the report (2016).
  4. Record the conformance status (i.e. accepted or rejected) of the orifice plate bore diameter and roundness on the inspection worksheet.

    Notes: Where orifice plate bore diameter is greater than that permitted by a reduced βr, the orifice plate cannot be used in trade or custody transfer applications.

  5. Where applicable, cancel any verification stamp to indicate the rejection of the orifice plate.

D8.5 Orifice plate bore thickness ( e )

  1. Ensure the orifice plate is under thermally stable conditions, measure the temperature ( Tm ) of the orifice plate with a certified thermometer and record the Tm to the nearest degree Fahrenheit (0.5 °C) on the inspection worksheet.

    Notes: Thermally stable conditions mean that the temperature is constant within 1 °F (0.5 °C) at time of diameter measurements.

  2. Measure the orifice plate bore thickness ( e ) as required on the dimension sketch of the inspection worksheet and record it.
  3. Compare the measured e to the requirements specified in 4.5 of the report (2016).
  4. Record the conformance status (i.e. accepted or rejected) of the orifice plate bore thickness on the inspection worksheet.
  5. Where applicable, cancel any verification stamp to indicate the rejection of the orifice plate.

    Notes: Where the orifice plate bore thickness does not meet the specified requirements, the orifice plate cannot be used in trade or custody transfer applications.

D8.6 Orifice plate thickness ( E )

  1. Ensure the orifice plate is under thermally stable conditions, measure the temperature ( Tm ) of the orifice plate with a certified thermometer and record the Tm to the nearest degree Fahrenheit (0.5 °C) on the inspection worksheet.

    Notes: Thermally stable conditions mean that the temperature is constant within 1 °F (0.5 °C) at time of diameter measurements.

  2. Measure the orifice plate thickness ( E ) as required on the dimension sketch of the inspection worksheet and record it.
  3. Compare the measured E to the requirements specified in 4.6 and Table 3 of the report (2016).
  4. Record the conformance status (i.e. accepted or rejected) of the thickness of the orifice plate on the inspection worksheet.
  5. Where applicable, cancel any verification stamp to indicate the rejection of the orifice plate.

    Notes: Where the orifice plate thickness does not meet the specified requirements, the orifice plate cannot be used in trade or custody transfer applications.

D8.7 Orifice plate bevel (Ɵ)

  1. Ensure the orifice plate is under thermally stable conditions, measure the temperature ( Tm ) of the orifice plate with a certified thermometer and record the measured Tm to the nearest degree Fahrenheit (0.5° C) on the inspection worksheet.

    Notes: Thermally stable conditions mean that the temperature is constant within 1 °F (0.5 °C) at time of diameter measurements.

  2. Measure the orifice plate bevel angle (Ɵ) as required on the dimension sketch of the inspection worksheet and record it.
  3. Compare the measured Ɵ to the requirements specified in 4.7 of the report (2016).
  4. Record the conformance status (i.e. accepted or rejected) of the orifice plate bevel angle on the inspection worksheet.
  5. Where applicable, cancel any verification stamp to indicate the rejection of the orifice plate.

    Notes: Where the orifice plate bevel angle does not meet the specified requirements, the orifice plate cannot be used in trade or custody transfer applications.