**Summary of Comments**

**Notice of Proposed Rulemaking (NPRM): Use of Polyamide-11 (PA-11)**

**Plastic Pipe in Gas Pipelines**

PHMSA received 13 comments on the use of polyamide-11 (PA-11) plastic
pipe from 10 commenters. Commenters included industry trade groups,
natural gas distribution utility companies, plastic pipe consultants,
and the original petitioner. Of the 10 comments, all but one expressed
support for the proposed increases in design pressure limit and design
factor. Of the 9 other comments, 4 supported the increases in design
pressure limit and design faction, but opposed the proposed amendment to
49 CFR 192.123(f)(4) on the mandatory burial of a warning tape or other
device. The single commenter opposed to the proposed amendments sent in
two separate comments, one of which did not apply to the rulemaking in
question.

The supporting commenters cited laboratory test results from the Gas
Research Institute (formerly the Gas Technology Institute), and the
results that PA-11 pipe material can perform at the proposed limits
without compromising public safety. Two of the supporting commenters
noted that they were currently operating PA-11 pipelines under waivers.
Commenters also cited the benefits of using PA-11 pipe as an alternative
to metal for gas distribution pipelines, and cost efficiencies for
installation and maintenance as reasons to support the proposed rule.

*[Warning Tape]{.underline}*

Four commenters objected to the proposed rule in §192.123(f)(4) on the
mandatory burial of warning tape or another device to warn an excavator
of the presence of a high-pressure gas line. Most believed the
requirements are unnecessary and impractical and may be overly
burdensome because of the technical difficulty of burying the warning
tape. Several commenters expressed concerns the amendment could cause
confusion because of possible inconsistent application of these to PA-11
pipe operating above 100 psig compared to other plastic and metallic
pipe operating above 100 psig. The commenters stated that operator
confusion could reduce the effectiveness of these and other markers.
Some commenters argued to strengthening existing requirements for damage
prevention programs and excavator awareness training as a better
alternative. One commenter suggested moving the requirement under 49 CFR
192.321(e), Installation of Plastic Pipe, and that it should not apply
to a pipeline installed within casing or a sleeve.

*[Opposition to the Proposed Increases in Design Pressure Limit and
Design Factor]{.underline}*

Sempra Energy Utilities (Sempra), representing Southern California Gas
Company and San Diego Gas and Electric, filed the one comment opposing
the proposed rulemaking. Sempra bases its opposition on the following:

1.  Discrepancies Between Resin Formulations, HDB and Field Performance
    Data

During the field trials, Arkema discovered its new formula for the
pigment coloring of the PA-11 pipes, which was designed to reduce heavy
metals in its products and waste streams, caused an unexpected oxidation
problem. Once Arkema identified the cause of the problem, it changed the
formula to be closer to an earlier formula with a proven track record to
eliminate the problematic element. Arkema also performed analyzes,
including tests of the Nicor Gas Pipeline operated under a waiver, to
determine if the same "accelerated degradation mechanism" was at work in
the newest formula and determined it was not.

Sempra argues this new information should require more testing to
establish the HDB of the material. Arkema responds that it received the
PPI TR4 HDB listing after considerating the data by the HSB and this
data included HDB equivalency testing at an independent ISO-certified
laboratory.

Two respected plastic pipe consultants also responded that HDB testing
is not intended to find issues such as the oxidation problem, and that
changes to the pigment formulation has no effect on the HDB as
determined by ASTM D2837.

PHMSA is satisfied the oxidation problem has been resolved by Arkema and
that the HDB of the PA-11 material has been properly established.

2.  Advanced Approach for Determining Design Factor for Plastic
    Materials

Sempra states there is research underway to develop a technically sound
approach to increase the design factor from 0.32 to 0.40 for PE pipes
without adversely compromising system integrity and overall safety. They
opine that a material must demonstrate there is ample balance between
its long-term strength and long-term in-service stresses acting on the
piping system. They add testing must be performed simulating additional
stresses acting on the pipe (such as point loads, excessive bending
strain, compaction, earth loading, etc.) to validate safe operations at
increased pressures and that no test or field trial data has been
provided to demonstrate that this is true for PA-11.

Arkema responds that combined loading tests are not relevant to PA-11
because extensive laboratory testing intended to identify slow crack
growth (SCG) has shown that PA-11 is highly resistant to SCG. They add
that SCG has never been observed in PA-11.

A respected plastic pipe consultant also responded that the testing
suggested by Sempra is appropriate for PE material, but not for PA-11
materials because PA-11 does not fail by SCG.

Based on the extensive laboratory research, field research and the field
trail experience, and opinions from plastic pipe experts, PHMSA accepts
that PA-11 is not likely to fail due to SCG and that additional combined
loading testing is not warranted.

3.  Clarification of Regulatory Requirements at Increased Operating
    Pressures

Sempra suggests PHMSA provide additional clarification regarding the
integrity management (IM) requirements that would apply to PA-11 at the
proposed higher operating pressures and stresses. PHMSA disagrees with
Sempra's premise that the IM regulations in 49 CFR Part 192, Subpart O,
are somehow based on the type of plastic material. That is incorrect.
While PHMSA acknowledges there are specific IM requirements that
operators of PA-11 pipelines must address, the same can be said of
polyethylene (PE) and other plastic pipelines. The existing IM
regulations apply to all regulated plastic pipelines as described in the
code, and there is nothing in this Rule to exempt PA-11 from the
existing IM regulations.

PHMSA has an IM web site, IM frequently asked questions (FAQs) and other
mechanisms that an operator can use to help clarify any PA-11 specific
IM issues that may arise. PHMSA also offers written interpretations to
the code to help clarify specific issues.

Lastly, if the IM regulations are found insufficient to address PA-11
pipelines, Sempra or any other interested person can petition PHMSA for
a change of the IM regulations in accordance with 49 CFR 190.331.

4.  Possible Misapplication of Stresses to HDB Ratio

Sempra points out that PHMSA made an incorrect mathematical correlation
in the NPRM. PHMSA acknowledges the error, but Sempra's argument that
this impacts the supporting rationale for this rulemaking is specious.
The simplified correlation was not in any of the petitions by Arkema. It
was simply our intent to explain to the general public and other
stakeholders unfamiliar with plastic pipe that PA-11 has an HDB twice
that of PE 2406, and when held to the same design pressure limitations
as PE 2406, it is actually being held to tighter standards than PE 2406.

Moreover, PHMSA did not intend this correlation to establish the maximum
pressure limitation for plastic pie as Sempra asserts. While we admit
this error, we find Sempra's argument moot in light of the amount of
other supporting material represented by the petitioner, plastic pipe
experts and by the overwhelming support for this Rule in the plastic
pipe industry.