PHMSA Briefing Paper November 14, 2023

![](media/image1.png){width="6.0in" height="0.1in"}

**Notice of Proposed Rulemaking (NPRM): Pipeline Safety: Use of
Polyamide-11 (PA-11) Plastic Pipe in Gas Pipelines**

Advisory Committee Action: Vote

Project Contact: Richard Sanders

Summary:

-   PHMSA issued an NPRM (73 FR 1307) proposing to revise the Federal
    pipeline safety regulations to allow certain thermoplastic pipelines
    made from new PA-11 pipe to be designed using a higher design factor
    and to raise the design pressure limit for the same pipelines.

-   Throughout 2007, PHMSA met with utility representatives and pipeline
    construction companies' senior project engineers to monitor
    manufacturing processes; review waiver requests; and discuss
    directional boring techniques, equipment and types of strain gauges
    to review extensive laboratory and field data on the PA-11 material.

-   In April 2006, ASTM approved a new "Standard Specification for
    Electrofusion Type Polyamide-11 Fittings for Outside Diameter
    Controlled Polyamide-11 Pipe and Tubing," which is the design
    standard and quality rule for PA-11 electrofusion fittings.

-   In the June 22, 2005, Federal Register (70 FR 36093), an Advanced
    Notice or Proposed Rulemaking was published to seek comments on the
    Arkema petitions of October 2004. The Arkema petitions requested an
    increase in the design factor from 0.32 to 0.40 in the plastic pipe
    design formula in §192.121 for new PA-11 plastic pipes, and an
    increase in the design pressure limits in §192.123 from 100 psig to
    200 psig for 2-inch IPS, PA-11 plastic pipe. The comment period
    closed mid-August 2005 (9 positive comments, 0 negative comments).

[What PHMSA Proposes]{.underline}:

-   Allow new 4-inch IPS or less, SDR-11, PA-11 pipelines to be designed
    using a design factor of 0.40 (instead of 0.32) in the plastic pipe
    design formulas in §192.121.

-   Increase the design pressure limit in §192.123 from 100 psig to 200
    psig for new 4-inch IPS or less, SDR-11, PA-11 plastic pipe used in
    pipeline systems. Service line piping may have larger SDRs.

  -------------------------- ------------- ---------------- --------------
  **From ASTM D 2513**                                      

  **CTS**                    **OD**        **Min Wall**     **SDR**

  1/2                        0.625         0.090            6.9

  1/2                        0.625         0.104            6.0

  3/4                        0.875         0.090            9.7

  1                          1.125         0.121            9.3
  -------------------------- ------------- ---------------- --------------

+-----------------------+-----------------------+-----------------------+
| **ASTM D2513 - Table  |                       |                       |
| 3**                   |                       |                       |
|                       |                       |                       |
| **Wall Thicknesses    |                       |                       |
| and Tolerances for    |                       |                       |
| Plastic Pipe, in      |                       |                       |
| (mm)**                |                       |                       |
+-----------------------+-----------------------+-----------------------+
| Nominal Pipe Size     | DR*^C^*               | Minimum               |
|                       |                       |                       |
| (IPS)                 |                       |                       |
+-----------------------+-----------------------+-----------------------+
| ½                     | 9.33                  | 0.090 (2.29)          |
+-----------------------+-----------------------+-----------------------+
| ¾                     | *11.0*                | 0.095 (2.41)          |
|                       |                       |                       |
|                       | *Sch 40*              | 0.113 (2.87)          |
+-----------------------+-----------------------+-----------------------+
| 1                     | *11.0*                | 0.120 (3.05)          |
|                       |                       |                       |
|                       | *9.9*                 | 0.133(3.38)           |
|                       |                       |                       |
|                       | *9.33*                | 0.140 (3.56)          |
+-----------------------+-----------------------+-----------------------+
| 1 ¼                   | 11.0                  | 0.151 (3.84)          |
|                       |                       |                       |
|                       | 10.0                  | 0.166 (4.22)          |
|                       |                       |                       |
|                       | 9.33                  | 0.178 (4.52)          |
|                       |                       |                       |
|                       | 6.0                   | 0.277 (7.04)          |
+-----------------------+-----------------------+-----------------------+
| 1 ½                   | 11                    | 0.173 (4.39)          |
+-----------------------+-----------------------+-----------------------+
| 2                     | 11                    | 0.216 (5.49)          |
|                       |                       |                       |
|                       | 9.33                  | 0.255 (6.48)          |
+-----------------------+-----------------------+-----------------------+
| 4                     | 11.0                  | 0.409 (10.39)         |
|                       |                       |                       |
|                       | 9.33                  | 0.482 (12.24)         |
+-----------------------+-----------------------+-----------------------+

-   Locating requirement will remain the same as stated in regulations
    based on comments received concerning PA-11 NPRM.

-   The SDR-11 wall thickness is the thinnest wall thickness allowed.