COMMENTS OF THE
WILLIAMS GAS PIPELINE
NOTICE OF PROPOSED RULEMAKING
Pipeline Safety: Standards for Increasing the
Maximum Allowable Operating Pressure
For Gas Transmission Pipelines
Docket ID PHMSA-2005-23447; Notice 2
Docket No. RIN 2137-AE25
Pursuant to the proposed rulemaking notice (“Proposed Rule”) issued by
the U.S.
Department of Transportation (“DOT”) Pipeline and Hazardous Materials
Safety
Administrations (“PHMSA”) on March 12, 200, Federal Register Vol. 73, No.
49,
13167, Williams Gas Pipeline (“WGP”), 2800 Post Oak Boulevard,
Houston,
Texas 77056 submits the following comments on PHMSA’s proposal to
amend the
pipeline safety regulations to prescribe safety requirements for the
operation of
certain gas transmission pipeline at pressure based on higher stress levels.
Industry has been working with PHMSA on these criteria for 3 years. In
addition,
individual companies, through the special permit process have been
working with
PHMSA to set reasonable requirements. Some of the requirements set by
PHMSA are not supported by any technical data or information. WGP
therefore
will be providing comments on those items.
Also during the special permit process, companies are inclined to agree
with
PHMSA requirements in order to get the permit as expeditiously as
possible;
costs of delays are not tenable. Therefore, companies have agreed to non-
technically based requirements in order to get the permit. These issues will
be
addressed by WGP in the response for individual items.
GENERAL COMMENTS
Several operators have sought and/or been granted Special Permits to
operate at
higher stress levels. WGP is concerned that these Special Permits will be
revoked
and the requirements of the proposed rule implemented. This may cause
an undo
hardship on the companies that have invested significant resources to meet
the
requirements of the Special Permits. All Special Permits should be
grandfathered.
A company should, however be allowed to suspend operations under the
Special
Permit and instead follow the proposed regulations.
Many of the proposed requirements seem to ignore the requirements and
criteria
set forth in Subpart O and the referenced ASME B31.8S standard. These
proposed requirements do not have a technical basis and there need is not
explained where as the requirements in Subpart O and in ASME B31.8S are
based on science and technical research. Where the elements of integrity
management are required, it is recommended that reference to Subpart O
be
made instead of stating new, unjustified and conflicting requirements.
COMMENTS ON THE PREAMBLE
The preamble has a few errors that WGP wishes to point out so that the
final rule
will be correct. In addition, comments on some questions posed in the
preamble
are provided These changes and comments are as follows:
B.1 The phrase “but not to exceed 80% of MSYS” at the end of
paragraph
one is not correct. There is no upper limit to the pressure under which a
grandfathered pipeline can operate.
B.6 Paragraph one, the review of existing permits, may be an
appropriate
action for PHMSA to take. PHMSA should not use this review to impose
additional
requirements on those operators which Special Permits nor revoke any
Special
Permits already granted.
B.6 Paragraph two, PHMSA should continue to expeditiously process
any
Special Permits they receive regardless of the status of this proposed
rulemaking.
The operators who have submitted the Special Permits may need to
increase
pressure to meet customer demand before the rulemaking is complete.
Additionally, operators may need relief from both existing regulations and
the
proposed regulations as drafted.
C.3 Paragraph two makes reference to “level 2 of API Specification 5L’.
The
new edition of this specification will likely be published before this
rulemaking is
complete. The reference, as stated will be outdated. PHMSA should review
the
proposed new edition of this specification and make appropriate references
as part
of the final rule.
C.3 Paragraph eight requires certification of serviceability for fittings and
other components. It is not known what this requirement means. PHMSA
should
clarify this requirement; does PHMSA mean that mill certificates are
required for
each component?
C.4 Paragraph four states that “industry practice has been to non-
destructively test only a sample of girth welds”. WGP takes exception to this
statement. Although this represents the regulatory requirement, industry
practice,
including WGP is to non-destructively test nearly all girth welds.
C.4 Paragraph six states that “since the initial strength test is a
destructive
test, it only detects flaws relatively close to failure during operation. This
could
leave in place smaller flaws that could grow more rapidly at higher stress
levels.
WGP takes exception to this statement. The pressure test eliminates all
flaws
that may fail significantly above operating pressure and to the level of the
strength
test (1.25 times MAOP or greater). Any flaws left in place will not grow more
rapidly at higher stress levels and there is nothing that will cause them to
grow.
PHSMA should review research on pressure testing to more accurately
state the
how flaws are manifested and grow and how pressure testing minimizes the
material and construction threats.
C.7.7 Paragraph one implies that geometry tools are run for baseline
purposes and during periodic assessments. This is not a correct statement
based
on the proposed regulations. Geometry tools are required for the baseline
assessment but not for periodic assessments. The language in the
proposed rule
is correct.
C.7.8 Paragraph one states that “The higher stress levels of operation can
allow more rapid growth of materials”. This statement is not correct. The
growth of
anomalies is not depended on operating stress level.
D.2 Paragraph 4 has a statement that is not correct. “In the case of new
pipelines, the ability to use an alternative MAOP will make it possible to
transport
more product”. This statement may be true for existing pipelines but new
pipelines
are designed for the required capacity as certificated regardless of
operating
stress level.
COMMENTS ON PROPOSED CHANGES TO PARAGRAPH 192.7–
INCORPORATION BY REFERENCE
In general, WGP supports the use of consensus standards to provide the
technical
foundation for any regulatory actions; particularly those developed under the
provisions established by the American National Standards Institute (ANSI).
Specifically, WGP supports the incorporation of the standard, ASTM A
578/A579M-96 (re-approved 2001) “Standard Specification for Straight-
Beam
Ultrasonic Examination of Plain and Clad Steel Plates for Special
Applications” for
use in inspecting plate manufactured for pipe orders to be used for
operation using
the alternative design basis and life cycle management proposed by
PHMSA.
COMMENTS ON PROPOSED PARAGRAPH 192.112
This new paragraph sets the eligibility requirements for a new or existing
pipeline
to operate at the alternative maximum allowable MAOP. WGP’s comments
to the
new language are as follows:
Paragraph (a) – General Standards for Steel Pipe
PHMSA proposes the use of a ratio of the diameter over the nominal wall
thickness, referred to as D/t to address the threat of damage during
construction
and atypical loads and mechanical damage during operation of the pipeline.
WGP
believes that while consideration of the relationship between wall thickness
relative
to pipe diameter is important, there is no hard and fast threshold that applies
under all circumstances. D/t limitations are particularly inappropriate for
higher
yield strength pipe. For pipe grades X-80 and above, the D/t ratios may
exceed
100 to 1. Ovality and denting issues can be managed for these higher D/t
pipelines, and for that matter any pipe under this regulation through the
construction practices proposed by PHMSA in 192.328(a)(1), Quality
Assurance
(during construction), and by provisions in the existing ASME code that
relate to
analyses of instantaneous and sustained loads during operation (ASME
B31.8,
Paragraph 833.4).
With respect to carbon equivalents, the consensus standard API 5L
establishes
specifications for maximum carbon equivalents using the Ito-Bessyo
formula (Pcm
formula) for varying grades and wall thicknesses of steel pipe. PHMSA has
proposed limitations that differ from those in API 5L, without technical
justification.
WGP supports use of the limits as expressed in API 5L, absent any other
information to justify differing limits.
Paragraph (b) – Fracture Control
In general, WGP agrees with the approach proposed by PHMSA with
respect to
fracture control. It is critical that an operator’s plan considers and addresses
initiation, propagation and arrest under the range of operating pressures and
temperatures anticipated on the pipeline. In addition, it is important that the
fracture control plan addresses the potential under-conservatism of
conventional
Charpy toughness equations for higher strength steels (grades X70 and
above) and
enriched gases. A White Paper “Fracture Control” has been developed by
the Joint
Industry Project on Alternative Design Basis and Life Cycle Management,
and it
supports WGP’s comments.
WGP agrees that the basis for arrest proposed by PHMSA is appropriate
for new
pipeline design. The basis selected by PHMSA in effect requires that
approximately 58 percent of the pipe be arrest pipe. This basis is also
appropriate
for existing pipelines as well except under one design scenario; that is a
scenario
under which a crack arrest design is used. WGP proposes that PHMSA
amend
the regulatory language to allow an operator to alternatively apply a crack
arrest
design based on an engineering analysis including an analysis of
consequence.
WGP recommends that the language under 192.112(b)(3) be changed to
read “If it
is not physically possible to achieve the pipeline toughness properties of
paragraphs’ (b)(1) and (2) of this section, a crack arrest design must be
developed
and implemented or mechanical crack arrestors of proper design and
spacing
must be used to insure fracture arrest as described in (b)(2)(iii) of this
section”.
Paragraph (c) – Plate/Coil Quality Control
In general WGP believes that the consensus standard API 5L provides the
foundation for the materials specification and manufacturing of line pipe.
Operators
(purchasers of pipe) build upon API 5L through use of materials
specification and
manufacturing quality management programs. The Joint Industry Project on
Alternative Design Basis and Life Cycle Management has developed a
White
Paper “Material Specification and Manufacturing” that describes how line
pipe
metallurgical, chemical and dimensional properties are managed by a
materials
and manufacturing quality management program. Materials and
manufacturing
quality management programs draw upon international consensus-based
standards in combination with mill and source-specific specifications, quality
control measures used by the pipe mill and quality assurance used by the
purchaser. The quality management program comprises four steps:
1. Pipe manufacturing mill qualification
2. Pipe standard, specifications and contracting agreements
3. Pipe manufacturing procedure specification review and agreement
4. Surveillance and auditing
The purchaser engages in a technical evaluation of the mill to ensure that
the mill
is qualified to produce pipe to the purchaser’s specifications. The
purchaser will
establish a pipe specification knowing the requirements of the project for
which the
pipe is being procured. The mill and purchaser engage in the development
and
agreement upon a manufacturing procedure specification (MPS) that
establishes
the materials specification to standards and the purchaser’s additional
requirements and manufacturing procedures and quality control/quality
assurance
(QA/QC) practices. The mill knows best how to source the steel, roll and
weld
pipe to meet the performance parameters required by the purchaser. The
MPS
sets out the kinds of inspections and frequencies and how exceptions are
to be
dealt with. The MPS is designed to locate issues before they become
problems
and minimize exceptions.
Steel properties are specified by the operator in the pipe specification and
the mill
selects the chemical formulations that are designed to ensure the slab mill
producer, skelp mill and the pipe mill achieve the desired final properties in
the
finished pipes. Most alloying elements must fall within compositional limits
that
are known to lead to the appropriate mechanical properties. Solidification
control
during continuous casting minimizes centerline segregation and lamination
from
refractory and slag entrapment.
Centerline segregation and lamination in the pipe body or pipe ends if it
extends
into the weld preparation generally reduces weld strength and may promote
girth
weld cracking. In particular, carbon, oxygen, sulfur and phosphorous in the
carbon
equivalents formulation are minimized controlled to promote weldability, and
the
controlled rolling (and accelerated cooling/strip coiling where applicable)
using
advanced thermo-mechanical parameters, and micro-alloying elements are
used to
assure the fine grain size and precipitation hardening effects which
compensates
for the loss of strength, due to the reduced carbon.
It is important to recognize that API 5L provides performance-based
requirements
to address the outcomes of centerline segregation, or failure of the source
material
to meet the metallurgical and dimensional properties of the operator’s pipe
specification and API 5L. The operator, the pipe mill and source mill must
balance
the use of quality control measures and the potential for out-of-spec pipe to
be
formed. This is not best achieved by the imposition of a single simple
prescriptive
approach unrelated to the negotiated MPS. Delays always lead to increase
cost,
and these will occur by improperly imposing production constraints.
Even considering the performance-based requirements set forth in API 5L,
WGP
recommends that the purchaser require specific slab mill inspections, such
as
macro-etch testing. Macro-etch testing is a valuable quality control method
to be
applied by the mill. This approach aligns with the approach proposed by
PHMSA.
While WGP agrees with PHMSA in the value of the tests, the frequency and
acceptance criteria are best left to be agreed upon between the purchaser
and the
mill, based on mill configuration, slab source materials among others.
WGP recommends that the language under 192.112(c)(2)(i)) be changed to
read “A macro etch test or other equivalent method to identify inclusions
that may
form centerline segregation during the continuous casting process. The
acceptance criteria must be agreed to between the purchase and the mill”.
With respect to ultrasonic inspection of plate/coil or pipe, WGP agrees that
the
pipe mill must include a comprehensive plate/coil and pipe mill inspection
program
to check for surface defects and inclusions that can be injurious to the
integrity of
the pipe. This program can be conducted on plate or rolled pipe (body and
all
ends) ultrasonic testing (UT) inspection program using as a basis,
guidelines in
ASTM A578 to check for imperfections such as laminations. Alternatively,
WGP
believes that the pipe mill may conduct full-body UT of the pipe. Full-body
UT
entails the use of a single transducer oscillating back and forth across the
internal
pipe surface. The basis of either approach is to assure that the inspection
finds
defects that exceed a certain minimum size in the body of the plate or pipe,
and
provides coverage for 100 percent of the pipe ends back a specified
length. The
work group recommends that the performance criteria set forth in ASTM
578 be
used for plate inspection and as a basis for establishing criteria for full-body
UT.
Paragraph (d) – Seam Quality Control
As a starting point, WGP believes that API 5L provides the technical
foundation for
managing seam quality control. The pipe weld seam must meet the
minimum
requirements for tensile strength as specified in API 5L for the appropriate
pipe
grade properties. WGP is aware of the work being undertaken by the Joint
Industry
Project on Alternative Design Basis and Life Cycle Management. The JIP
has
developed a white paper on Materials Specification and Manufacturing and it
supports WGP’s comments.
WGP agrees with PHMSA that pipe weld seam hardness test using the
Vickers
hardness testing of a cross-section from the weld seam confirms adequate
ductility across the plate, HAZ, and weld material volumes and must be
performed
on one length of pipe from each heat. WGP does not agree with the use of
a
threshold value of 280 Vickers Hardness (Hv 10). While API 5L does
provide such
a threshold value for sour gas service, it does not provide a single, fixed
value for
the gas service addressed under 49 CFR 192; that is the transportation of
non-
corrosive gases. WGP believes that the pipe mill and the purchaser should
establish a hardness maximum in the manufacturing procedure specification
and
quality assurance plan.
API 5L requires that the pipe weld seam must be 100 percent UT or x-ray
inspected to ensure there are no defects or cracks. In addition, API 5L
requires
that pipe ends be non-destructively inspected by either UT or x-ray, to
identify
there are injurious laminations or inclusions interacting the weld volume.
WGP recommends that the language under 192.112(d)(2) be changed to
read “There must be a hardness test method used to ensure hardness
levels
established between the purchaser and the mill of the following:…”
Paragraph (e) – Mill Hydrostatic Test
WGP understands that the mill hydrostatic test is really a quality control test
conducted on each pipe manufactured in the mill. It is an important quality
control
test but none-the-less it is a quality control test. The ultimate test of the
pipe’s
integrity is the eight-hour pressure test, often referred to as the proof test,
conducted on the pipe as constructed in the field.
WGP is aware of the work being undertaken by the Joint Industry Project on
Alternative Design Basis and Life Cycle Management. The JIP has
developed a
White Paper “Materials Specification and Manufacturing” and it supports
WGP’s
comments. The JIP work group examined hydrostatic testing practices in
modern
mills around the world and found that most operators specify a hydrostatic
test of
95 percent of the specified minimum yield strength (SMYS) for a duration of
15
seconds. API 5L in the forty-third edition and for a number of years has
specified a
test to 90 percent of SMYS for 10 seconds . The members of the JIP work
group
discussed test pressure and duration and reached the following
conclusions.
Testing to 95 percent of SMYS is appropriate as long as the current
provisions
that allow for end-loading compensation as per Appendix K are applicable.
In
addition, the work group considered the additional 10 seconds proposed by
PHMSA beyond the 10 seconds stipulated in API 5L is are also prudent.
The work
group found that a duration in excess of 10 seconds did not add value to
the test.
Consequently, the work group recommends,
WGP recommends that the language under 192.112(e)(1) be changed to
read “A
hydrostatic test of all pipe will be conducted in the pipe mill at a pressure of
at
least 95% of SMYS, for a duration of 10 seconds including the allowance
for end
loading”
Paragraph (f) - Coating
Fusion bonded epoxy coatings (FBE) have proven performance in pipeline
applications for over thirty years around the world. WGP believes that it is
important to allow for alternatives to ensure improved technologies are not
arbitrarily restricted. Three layer coatings especially FBE-PE and other
hybrids
have provided good performance in other parts of the world. Performance
coatings
that have been shown as semi-conductive and/or do not crack would be
preferred
over this “one size fits all” statement. Abrasion resistant coatings and other
high
integrity specialty coatings need inclusion through performance language
such as
non-disbonding, non-shielding, or non-cracking. Prescriptive language
remains
inappropriate because it risks stifling innovation. Regulations should allow
the use
of manufacturer’s coating performances on petition.
WGP recommends that performance language be used to describe the
expected
coating performance rather than specify only FBE coatings. This language
should
be “the pipeline must be protected against external corrosion by non-
disbonding,
non-shielding, non-cracking coating”.
WGP agrees with the quality assurance approach proposed by PHMSA at
192.112
(f)(3).
Paragraph (g) – Fittings and Flanges.
WGP agrees with the provisions proposed by PHMSA. But to clarify, pipe
fittings,
valves and flanges, associated with line pipe and main line block valves,
should be
designed and purchased in accordance with applicable reference standards
or
their equivalent, already incorporated within 49 CFR 192. The referenced
standards
may be supplemented by the operator’s supplemental requirements to
ensure the
materials meet the minimum engineering design specifications. In all cases,
the
valves and flanges should be ANSI Class 600 for pressures up to and
including
1,480 psig, and ANSI 900 for pressures up to 2,200 psig. Valves should be
manufactured in accordance with API 6D. High-test flanges should be
manufactured in accordance with MSS SP-44 and normal flanges in
accordance
with ASME B16.5. Small pipe fittings should be manufactured in
accordance with
ASME B16.9 and large fittings with MSS SP-7. All of these materials should
be
pressure tested in accordance with the applicable standards.
Paragraph (h) – Compressor Stations
PHMSA concerns with respect to compressor station discharge
temperatures
relate to the long-term durability and integrity of plant and field applied
fusion bond
epoxy (FBE) coating for operations greater than 120oF. The concern arises
when
considering operating scenarios for uncontrolled compressor discharge
temperatures projected to heat the downstream pipe to a temperature that
may
reach 150oF.
All pipelines built under PHMSA regulations must have two corrosion
protection
systems. The first line of defense against corrosion is the coating system
and the
second line of defense is the applied cathodic protection current. PHMSA
in
49CFR192 requires a minimum test point (or close interval survey) voltage
to
ensure the imposed current provides sufficient protection in the event the
coating
has deteriorated.
The FBE concern arises out of historical experience in the pipeline industry
when
some pipeline systems were operated at temperatures above 120oF, even
as high
as 160oF. In many cases these early coatings were non conductive and
prevented the cathodic current from completing the circuit. The pipe
was “shielded”
and the applied potential could not protect the surface. Corrosion is
prevented by
applying small voltage potential. These earlier reports refer to tar and
asphalt
based coatings that predominated prior to the use of FBE.
Early FBE coatings did not appear in the US until about the mid 1970’s.
Over
time there was evidence that some pre-FBE coatings had degraded and
eventually
became blistered or disbonded from the pipe. FBE however, remains
conductive
even when disbonded and raised proud of the pipe. FBE coatings do not
block the
cathodic protection current, meaning that disbondment of the coating does
not
interrupt the cathodic protection system, and the imposed CP continues to
protect
the pipe from external corrosion and SCC.
Never the less, there remain two major concerns:
1. absent a coated surface, the underlying steel can be prone to
external
corrosion and
2. stress corrosion cracking (SCC) can occur under disbonded and
non-
conductive coatings.
It is known that the pipe shielded by disbonded non-conductive coating is
susceptible to SCC and more so for any pipe that has experienced
temperature
excursions in excess of 120ºF. The TCPL study (3), which had experience
temperature excursions to 150ºF (65ºC), concluded that the disbondment
of FBE
coatings did not present an integrity threat to a pipeline as long as cathodic
protection was present on the line.
NACE RP0394-2002, Standard for Application, Performance, and Quality
Control
of
Plant-Applied, Fusion-Bonded Epoxy External Pipe Coating, states in
section
6.1.5 that a minimum coating thickness of 12 mils is required to meet the
acceptance criteria for tests in the RP, including cathodic disbondment, for
temperatures up to 150oF. Pipeline operators interpret this standardized
practice
to mean that FBE coatings, applied with a thickness of at least 12 mils, are
appropriate for operating temperatures up to 150oF. Since the FBE has
been
used in pipeline construction, the normal practice is to verify the thickness,
and
the integrity of the pipeline coating using a high voltage Jeeping inspection,
as the
line is lowered into the ditch. Holidays are immediately repaired before
backfilling
the ditch.
The Joint Industry Project on Alternative Design Basis and Life Cycle
Management
has developed a White Paper “A Review of the Performance of Fusion-
Bonded
Epoxy Coatings on Pipelines at Operating Temperatures Above 120º F” is
a review
that summarizes operating and performance case histories, as well as
laboratory
and field-testing of the long-term performance of FBE coatings. This paper
documents that FBE coatings have demonstrated good adhesion and little
disbondment in both laboratory-testing environments and after 30 years of
operation at temperatures greater than 120oF on systems in the United
States,
Canada and the Middle East. In addition, FBE remains conductive even
when
disbonded as a continuous barrier like film proud of the pipe. However,
FBE
coatings do not block the cathodic protection current, meaning that
disbondment
of the coating does not interrupt the cathodic protection system, and the
imposed
CP current continues to protect the pipe from external corrosion and SCC.
The work summarized in the JIP white paper shows that even the first
generation
FBE coatings having seen as many as thirty years service have performed
well at
temperatures above 120oF. Even so, blistering and disbondment has been
observed on in-service lines in operation above 120oF. Laboratory tests
conducted
on FBE coatings in simulated environments at temperatures above 120oF
do
indicate a greater degree of disbondment as the temperature is increased
towards
200o F however any corrosion is minimized by the CP system.
FBE coating is known to be conductive, meaning that even when
disbonded,
cathodic protection remains effective. In-service experience described in
this white
paper confirms this behavior. FBE coatings do not shield the cathodic
protection
currents.
It is not apparent that additional laboratory testing on FBE coating at
temperatures
above 120oF will add any information not already known based on the
studies
described in this white paper. An operator may elect to conduct additional
laboratory testing.
Recognizing that there is the potential for disbondment, an operator may
elect to
conduct above ground surveys using close interval surveys to confirm the
effectiveness of the applied potential and use direct current voltage
gradient
(DCVG) surveys periodically to locate holidays, if any, in the FBE coating.
The
conductivity of FBE coatings ensures the integrity of the second line of
protection,
the applied CP system, is not compromised.
WGP recommends that the language under 192.112(h)(2) be changed to
read “If
research or testing shows that the coating will withstand …”
COMMENTS ON PROPOSED PARAGRAPH 192.328
Paragraph (a) – Quality Assurance
WGP agrees with these proposed requirements.
Paragraph (b) – Girth welds
Item (2) in this paragraph refers to pipelines that were constructed prior to
the
effective date of this rule. This requirement is in the wrong area of the
regulations.
Paragraph 328 is a construction requirement and is not a retro-active
requirement.
Paragraph 620 is an Operations requirement and applies retro-actively to all
pipelines.
WGP recommend removing item (b)(2) from paragraph 192.328 and
putting it in
paragraph 192.620, under (c)(3) in a manner that is similar to the
requirement for
pressure testing.
Paragraph (c) – Depth of Cover
WGP agrees with these proposed requirements.
Paragraph (d) – Initial strength testing
In a paper by John Kiefner, “Role of Hydrostatic Testing in Pipeline Integrity
Assessment” the technical benefits for the test is stated as follows:
“The purpose of hydrostatic testing a pipeline is to either eliminate any
defect that
might threaten its ability to sustain its maximum operating pressure or to
show
that none exists. A key work here is pressure. Hydrostatic testing consists
of
raising the pressure level above the operating pressure to see whether or
not any
defects with failure pressures above the operating pressure exist. If defects
fail and
are eliminated or if no failure occurs because no such defect exists, a safe
margin
of pressure above the operating pressure is demonstrated.”
This statement is the underlying philosophy for all pressure tests including
the
post construction test addressed in this paragraph. In the case of post
construction tests, the defects that the operator is trying to find or prove do
not
exist are material and construction defects.
This item deals specifically with “any failures indicative of fault in material”.
Material is produced as specified in the pipeline safety regulations and the
additional requirements of proposed 192.112. Even with the rigorous
controls,
there is a possibility that a piece of pipe will have a material defect. This
unacceptable pipe will be found during the pressure test if the defect is
large
enough to grow to failure. If it does not grow to failure, the safety margin is
sustained.
Special permits granted to date have addressed pressure test failures by
requiring
a root cause failure analysis. If a systemic issue was found during the test,
discussions had to be held with the regional offices. The requirement stated
in the
special permits is:
“Assessment of Test Failures: Any pipe failure occurring during the pre-in
service
hydrostatic test must undergo a root cause failure analysis to include a
metallurgical examination of the failed pipe. The results of this examination
must
preclude a systemic pipeline material issue and the results must be
reported to
PHMSA headquarters and the appropriate PHMSA regional office.”
The requirement as stated in the NPRM, by stating that “the segment must
not
experience any failure indicative of fault in material” during the hydrotest is
excessive. A root cause analysis of any test failure however is appropriate.
If there
is a systemic issue with the material more needs to be done to understand
and
address the issue.
WGP recommends that the language under 192.328(d) be changed to what
was
used in the special permits, namely “Any pipe failure occurring during the
pre-in
service hydrostatic test must undergo a root cause failure analysis to
include a
metallurgical examination of the failed pipe. The results of this examination
must
preclude a systemic pipeline material issue and the results must be
reported to
PHMSA headquarters and the appropriate PHMSA regional office.”
Paragraph (e) – Cathodic Protection
This paragraph is not necessary. Existing paragraph 192.455 requires that
cathodic protection must be installed and placed in operation within one
year after
the completion of construction.
WGP recommends removal of this paragraph. If necessary, a reference to
192.455
can be added in stead of restating the requirement.
Paragraph (f) – Interference currents
WGP agrees with these proposed requirements.
COMMENTS ON PROPOSED PARAGRAPH 192.620
Paragraph (a)
Stated requirements in the NPRM are more restrictive than current
regulations and
granted special permits. This inconsistency must be addressed in the
NPRM.
The design factors set in the NPRM do not recognize that the class location
may
change after the pipeline has been constructed. Special provisions are
provided in
the existing regulations to allow for the class location change without the
need for
pipe replacement. This provision is contingent on a pressure test to the next
class
location test factor.
Waivers have been granted to pipelines operating to 80% or more of SMYS
that
were grandfathered and have subsequently experienced a class change
from
Class 1 to Class 2. In order obtain this waiver, companies agreed to in-line
inspection of the pipeline and to employ additional preventative and
mitigative
measures such as those that are mandated within a company’s Integrity
Management Plan. Today, there are pipelines that have been granted
waivers to
operate at 80% or more of SMYS in Class 2 areas.
Waivers have been granted to pipelines operating at 60% or more of SMYS
in
Class 3 locations where the pressure test was not to the level required by
the
regulations (1.5 times MAOP). Waivers have been granted to pipelines
operating
at 72% or more of SMYS of design pressure in Class 3 locations, where
neither
the design nor the pressure test met the requirements of the regulations.
The
companies in these cases also agreed to in-line inspection of the pipeline
and
operations in accordance with the companies Integrity Management Plan.
The
granting of these waivers was part of the agreement reached between
PHMSA and
the industry in 2002 as part of the promulgation of the integrity management
regulations in order to help justify the extreme cost of the regulations. Many
of
these pipelines contain HCA’s.
There are significant inconsistencies between current regulations, current
waivers
granted to existing pipelines, and the proposed regulations. While changes
to
existing regulations is not part of the scope of the NPRM, there is no reason
to
confuse the issue again with this rule, it should be made simpler and more
in line
with current waivers.
The proposed regulations do not have a provision for compressor station,
meter
station, road crossings or fabricated assemblies to operate at higher
pressures.
As written, a compressor station in a Class 1 area can be operated at 80%
of
SMYS.
WGP recommends the following changes to proposed Paragraph 192.620
(a):
For the new pipelines that meet all of the special provisions in the NPRM, it
is
recommend that:
• Class 1 pipelines be limited to operation at 80% of SMYS and
pressure
tested to 1.25 times MAOP
• Class 2 pipelines be limited to operation at 67% of SMYS and
pressure
tested to 1.25 times MAOP
• Class 3 pipelines be limited to operation at 56% of SMYS and
pressure
tested to 1.5 times MAOP
• Station piping be limited to operation at 56% of SMYS and
pressure
tested to 1.5 times MAOP
• Fabricated assemblies would be limited to operation at 67% of SMY
and pressure tested to 1.25 times MAOP
• Uncased road and railroad crossing be limited to 67 % of SMYS in
Class 1 locations and to 56% of SMYS in Class 2 locations.
For Class location changes, it is recommended that a new paragraph be
added to
192.611 to provide the following:
• Pipe that operates at 80% and in accordance with paragraph
192.620
and changes from Class 1 to Class 2, can continue to operate up to 80%
SMYS
• Pipe that operates at 80% and changes from Class 2 to Class 3 or
from Class 1 to Class 3 would need to have the pressure lowered to 67%
of SMYS
or be replaced with pipe designed at 67% SMYS or less
• Pipe that operates at 67% and in accordance with paragraph
192.620
and changes from Class 2 to Class 3 can continue to operate at 67%
These class change provisions are necessary or operators will be asking
for
special permits in the very near future as population encroachment drives
the
class location to change from Class 1 to Class 2 or from Class 2 to Class 3.
These criteria also provides for consistency with Special Permits previously
granted and gives the operator flexibility in design for all pipeline facilities
It is important to note that the regulations require operations and
maintenance
activity frequency be based on the class location. The higher the class
location,
the more frequent the inspection or other activity is performed. These
provisions
address the slightly higher risk due to consequence by reducing the
likelihood of
an event through more frequent inspection.
A White Paper “Alternative Pipeline Design Pressures” has been
developed on this
topic. It discusses the current regulations, the special permits granted for
performing Integrity Management in lieu of replacing pipe and the proposed
regulations.
Paragraph (b)
Item (6)
The NPRM states that the segment must not experience any failures during
normal operations indicative of fault in material. This requirement is
excessive as
the failure may be a single event. If there is a failure, a root cause analysis
should
be conducted in order to ascertain that the failure is not indicative of a
systemic
materials issue. If there is a systemic issue with the material more needs to
be
done to understand and address the issue.
WGP recommends that the language under 192.620(b)(6) be changed to
read “Any pipe failure occurring during normal operations must undergo a
root
cause failure analysis to include a metallurgical examination of the failed
pipe. The
results of this examination must preclude a systemic pipeline material issue
and
the results must be reported to PHMSA headquarters and the appropriate
PHMSA
regional office.”
Paragraph (c)
Item (3)
This item shows the criteria for pressure testing in Class 1 areas but does
not say
anything about Class 2 or 3 areas. For pipelines that are presently in
operation
and are being up-rated to the higher pressures, the pressure test
requirements
should not be the same as required in paragraph (a) of this section.
For existing pipelines, pressure test levels may not have been to the levels
stated
in paragraph (a) of this section; however the tests may have been very near
those
levels. Some relief from this requirement should be allowed. In 192.328(b)
(2) the
requirement for weld NDE is somewhat reduced recognizing that every weld
may
have not have experienced NDE. This rationale should apply to pressure
tests as
well in order to gain some relief from the pressure test requirements.
In a paper written for Alliance Pipeline, and contained in the docket for their
waiver
or special permit for increasing operating pressure, Kiefner and Associates
concluded “there would be little additional benefit gained in terms of
demonstrating
that the pipeline is fit for the modest proposed increase in operating stress
by
repeating the hydrostatic test to the incrementally higher level necessary to
meet
the 1.25 factor”. The paper states the reason for these conclusions and
included
that more than ¾ of all joints were tested to 95% of SMYS, more than ½ of
all
joints were tested to 97% SMYS or greater and more than 1/3 of all the
joints were
tested to 99% of SMYS. In addition, the conclusions were justified by pipe
manufacturing controls, resistance to mechanical damage, the decay of
pressure
with distance downstream of compression, and the minimal difference in
safety
factor as compared to current regulations.
WGP recommends that Item 3 of Paragraph C be changed to the following:
(i) Perform a strength test as described in 192.505 to at least the factor
stated in
(a) of this section times the maximum allowable operating pressure: or
(ii) For a segment in existence prior to the effective date of this regulations,
and
the pressure test levels do note meet the requirements of 192.620(a)(ii) of
this
paragraph, certify, under paragraph (c)(1) of this section, that a strength test
was
conducted and provide an engineering critical analysis discussing the
relationship
of the pressure test to actual operating pressure and the affects of
remaining
defect size, pipe toughness, fracture control properties and fatigue on the
pipeline ”.
Paragraph (d)
Item (1) – Assessing threats:
The way in which item 1 is written implies that operation at the higher stress
levels
increases the risk and that the procedures used will mitigate the risk. The
slight
increase in risk however is already mitigated through all of the additional
design,
materials, construction, and operations requirements of these proposed
regulations. It is unclear what procedures are being talked about.
WGP recommends that this item be clarified to state that the operator must
include in their design, construction, material, operations, and maintenance
procedures and specifications, provisions to mitigate risk for operation at
the
higher design pressures.
Item (2) – Notifying the public:
This item appears to require a special notification to the public near
pipelines that
will be operating at higher pressures. The justification for this requirement
has not
been provided other than to state the information is necessary to people
potentially
impacted by a failure. Everyone along the pipeline could be affected by a
failure.
Notification about pipelines is already required by 192.616 “Public
awareness”.
WGP recommends item (d)(2) be revised to change the title of the section
to “Assessing potential impact area”. In addition, delete item (d)(2)(ii) in its
entirety.
Item (3) – Responding to an emergency in an area defined as a high
consequence
area:
This item states the requirements for timing of valve closure in an HCA.
WGP is
not aware of any study or research that supports this requirement. The
requirement seems arbitrary and is contrary to research and operational
experience.
Especially onerous is the requirement for additional pressure monitoring
upstream
and downstream of the valve. WGP is not aware of any benefit in monitoring
the
pipeline pressure upstream and downstream of the valve. Pressure
monitoring
requires additional equipment and the resultant maintenance where the
benefit is
not known and has not been justified. Given a rupture of the pipeline, the
pressure
will read zero after the valves are closed upstream and downstream of the
rupture
site. Upstream of the first closed valve the pressure will equalize to the
upstream
compressor station discharge pressure. Downstream of the second closed
valve
the pressure will equalize to the downstream compressor station suction
pressure.
There is no need for pressure monitoring.
In addition, the requirement to be able to remotely open the valve is contrary
to
many companies operations policies. Many operators believe that if the
situation
is so serious that remote closure of the valve is required, on-site personnel
should
make the determination that the area is safe prior to re-pressurizing the
segment
and therefore do not allow remote opening of the valve.
WGP recommends that 192.620(d)(3)(iii) be changed to read “Remote
valve control
must include the ability to close the valve and monitor the position (open
and
close) of the valve”.
Item (4) - Patrolling
The patrolling frequency proposed in the NPRM is excessive. WGP is not
aware of
any technical justification for the proposed frequency however it does
recognize
that it follows the frequency mandated for hazardous liquid pipelines.
A review of the incident data for both gas and hazardous liquid transmission
lines
does not show any benefit from the increased patrolling frequency for
hazardous
liquid lines. In 2007 there were 466 hazardous liquid incidents reported for
the
approximately 160,000 miles of pipeline. Of these there were 26 due to
third party
damage. For gas pipelines there were 127 incident reports for the
approximately
300,000 of pipeline. Of these 14 were due to third party damage. There
were
approximately 3.7 times more incidents reported for hazardous liquid
pipelines for
a population equal to 53% of the gas pipeline mileage. Taking these factors
into
account, the number of incidents for pipelines patrolled 26 times per year is
the
same as for those patrolled twice per year (twice per year is an average
required
number of patrols based on one per year for Class 1, two per year for Class
2 and
four per year for Class 3). This comparison is arrived by taking 26 third party
incidents for gas pipelines divided by (3.7 * .53) which equals 13, the
expected
number for gas incidents. This compares to the 14 actual incidents.
A report by CFER Technologies for PRCI shows that unless patrolling is
done at
least daily, there is not much chance of prevention for outside force
damage. In
addition, B31.8 only requires once per year in Class 1 and 2 even when
Class 1
pipe can operate at 80%.
WGP recommends changing the patrolling requirements to four times per
year
Class 1, six times per year in Class 2 and twelve times per year in Class 3.
This increase in frequency is akin to the frequency for the next higher class
location as are other of the additional requirements in the NPRM. For
example, the
requirement in the NPRM for NDE to 100% of all girth welds in Class 1
areas
operating at 80% of SMYS is the same as required in Class 3 areas in the
existing regulations.
Depth of Cover
The language used in the NPRM for maintaining depth of cover is
confusing. The
first sentence says to maintain depth of cover to the requirements stated in
192.327 or 192.328. The second sentence says that if observed conditions
indicate the possible loss of cover, perform a depth of cover survey and
replace
cover as necessary. The first sentence statement requiring that cover be
maintained is a requirement that can not be obtained in any practical sense.
The
second sentence statement is more in line with a performance requirement
that
can be obtained and is event driven.
Based on studies of incidents where depth of cover was recorded, it was
found
that there is no correlation between depth of cover and third party damage.
There
are situations where the removal of cover may pose a threat of damage to
the
pipeline due to third party activities such as in agricultural situations. In these
cases the restoration of cover may be appropriate.
There may be situations where cover can not be permanently restored. In
these
situations there may be more appropriate measures that can be employed,
such
as the addition of a barrier or some other prevention or mitigation measure.
For existing pipelines that were installed in accordance with 192.327, the
depth of
cover requirements in a Class 1 area was 30 inches. Some removal of
cover may
have occurred during the life of the pipeline do to agriculture, normal soil
erosion or
other factors. This paragraph, as written would require the operator to
maintain
cover to 30 inches for existing pipelines which may result in significant
environmental disturbance to replace cover over long segments of pipeline.
WGP recommends changing the language to eliminate the first sentence so
that it
reads “If observed conditions indicate the possible loss of cover in an area
where
damage to the pipeline may result due to the loss of cover, replace the
cover or
provide appropriate prevention and mitigation measures as necessary”.
Damage Prevention
The requirement to review the damage prevention program in light of
consensus
standards and practices and employ the appropriate practices into the
damage
prevention program seems appropriate. The language in this requirement
may lead
to many interpretations by the companies and by inspection personnel due
to its
ambiguity. The requirement, as stated, does not identify the standards or
practices to be reviewed, however it may be assumed that the CGA best
practices
are what are being referred to in this requirement. An operator may chose to
follow
one standard or practice; however inspection personnel may believe the
operator
should follow another. Another issue during inspections may be the
determination
of which items in a standard or practice should be followed by the operator.
WGP recommend changing the requirement so it reads “Review of CGA
best
practices and incorporation of the applicable practices into the operator’s
damage
prevention program”
Right-of-Way Plan
The requirement to develop and implement a right-of-way plan is duplicative
of an
operator’s damage prevention program and other requirements in the
regulations.
This additional program is not necessary or justified. The intent as stated is
to
protect the segment from damage due to excavation damage and this
requirement
is the same as required in a operator’s damage prevention programs as
stated in
192.614. Paragraph (a) of this section states “… each operator of a buried
pipeline
must carry out, in accordance with this section, a written program to prevent
damage to that pipeline from excavation damage…”.
The other conditions required by the proposed plan are already covered in
192.613 “Continuing surveillance”, 192.705 “Transmission Lines:
Patrolling”,
192.706 “Transmission Lines: Leakage surveys”. These items are
addressed in an
operator’s manual of operations and maintenance procedures as required
by
192.605 “Procedural manual for operations, maintenance, and emergency
response”.
WGP recommends removing 192.620(d)(4)(ii) and 192.620(d)(4)(vi) from
the
proposed regulations.
Item (5) – Controlling internal corrosion:
This proposed regulation is somewhat duplicative yet in conflict with the new
regulation at 192.476 “Internal corrosion control: Design and construction of
transmission line”. The new regulation provides specific requirements for
new
pipelines for the control of internal corrosion. The new regulation also has a
provision for “change to existing transmission line” which would apply to any
pipeline that is presently in operation and would be up-rated based on the
NPRM.
With conflicting regulations, the operator may not be able to meet both
requirements.
This proposed regulation also sets limits on gas quality. These limits may
be in
conflict with gas quality requirements set by FERC in an operator’s tariff. In
addition, there is no justification in the NPRM for the limits set.
The proposed regulation requires the use of cleaning pigs and inhibitors
and
sampling of accumulated liquids. This requirement is required regardless of
the
gas quality, whether or not there is liquid water and whether or not there are
other
prevention and mitigation options available to the operator. The language
used in
192.476 is better stated and covers all the same issues without the need to
mandate work that may not be needed.
In response to the new regulations at 192.476, INGAA companies,
including WGP
developed guidelines in order to assist pipeline operators in determining
the
requirements of this regulation. These guidelines “Internal Corrosion
Control:
Design and Construction of Transmission Line” should be used in
developing
regulations for internal corrosion control measures. In addition, a White
Paper, “Management of Time Dependent Threats” has been developed
which
discusses the concerns and remediation of gas quality issues.
WGP recommends revising 192.620(d(5) to read “develop and implement
a
program to monitor gas quality to prevent internal corrosion and to
remediate any
gas quality excursions where internal corrosion may result”
Item (6) – Controlling interference that can impact external corrosion:
WGP agrees with the proposed requirements.
Item (7) – Confirming external corrosion control through direct assessment:
The requirements in the NPRM and existing regulations provide several
layers of
protection for corrosion control. There are specific and comprehensive
requirements for coating application at both the mill and in the field. There
are
coating continuity checks after the coating is applied and again before the
pipe is
lowered into the ditch and backfilled. Cathodic protection test stations are
installed
during construction. A geometry tool is run after construction which checks
for
pipe and ultimately coating damage that may have been caused during
construction. Interference surveys are conducted within 6 months of placing
the
pipeline in operation. Cathodic protection is added within one year of
placing the
pipeline in operation. A close interval survey is conducted within six months
of
placing the cathodic protection in service. An in-line inspection with an MFL
tools
is performed within three years of placing the pipeline in service.
The proposed rule requires operators to “assess the integrity of the coating
and
adequacy of the cathodic protection through an indirect method such as
close-
interval survey, direct current voltage gradient or alternating current voltage
gradient”. Close-interval surveys are used to confirm the adequacy of
cathodic
protection. Voltage gradient surveys are used to determine coating defects.
Neither tool can meet both requirements. This implies that two separate
surveys
are required.
This proposed requirement also states that remediation of the coating must
be
performed based on NACE RP-0502 for any indication that is severe or
moderate.
This requirement is in conflict with the NACE standard which determines
severe or
moderate based on two or more above ground methods, not one.
The proposed regulation therefore implies that Direct Assessment must be
conducted on the pipeline after construction and installation of the cathodic
protection systems. These requirements together are excessive and not
necessary. These requirements are in addition to a pressure test and in-line
inspection with an MFL tool. This means that the pipeline must be assessed
using
all three tools identified in Subpart O of the pipeline safety regulations.
The close interval survey may be appropriate in order to confirm that the
cathodic
protection system is operating as designed. The coating survey is not
necessary;
any coating anomaly is protected from corrosion by the cathodic protection
system. In addition the requirement to base and respond to results based
on the
NACE ECDA standard is not necessary.
The requirement to perform the close interval survey within 6 months is
excessive
and in many cases not possible. CIS is not performed in winter months in
cold
climates and the time between completion of construction in the fall and CIS
in the
summer will exceed six months.
A White Paper “Management of Time Dependent Threats” has been
developed and
discusses the requirements and needs for corrosion control activities.
WGP recommends revising 192.620(d)(7)(i) to read “ Within one year of
placing
the cathodic protection of a new segment in operations or within one year
after
recalculating the maximum allowable operating pressure of an existing
segment
under this section, perform a close-interval survey to determine the
adequacy of
the cathodic protection system”
WGP recommends revising 192.620(d)(7)(ii) to read “Remediate the
coating or
insure cathodic protection levels are appropriate to mitigate corrosion”
This new requirement states that results of the above ground assessment
results
must be integrated with the ILI results within 6 months for performing the
ILI. This
timing is burdensome and not necessary. The value of this data integration
is not
explained or justified.
WGP recommend revising 192.620(d)(7)(iii) to read “Within one year…”.
This new requirement states that test stations be installed at half-mile
intervals in
HCA’s and that at least one station is in each HCA (see item B). In addition,
this
item does not seem to fit under the topic of periodic assessments. This
item may
better fit under 192.328(e) as a construction requirement. In addition
location of a
test station within the HCA may not be practical. For example a pipeline that
is
physically 600 feet from a church and in a farm field, but the church makes it
an
HCA; it is not practical to place the test station in the HCA which is in the
farm
field. The need for the ½ mile spacing is not justified and is contrary to
consensus
standards.
WGP recommends that this item should be moved to 192.328(e) and that it
could
be clearer if it states that “no location in an HCA can be further than one mile
from
a cathodic protection test station”.
This new requirement states that there must be periodic close interval
surveys of
the pipelines in HCA’s and that they are performed in association with
subpart O.
This statement is not clear. Subpart O addresses integrity management and
allows the use of one of three assessment techniques. Item 10 of this
paragraph
requires periodic in-line inspections at a frequency determined by the
operator.
This item implies that CIS is required at different intervals that the ILI
interval. The
need for close interval surveys is not justified or explained in the NPRM.
WGP recommends deletion of 192.620(d)(7)(iv) in its entirety once item (d)
(7)(iv)
(B) is moved to paragraph 192.328(e).
Item (8) – Controlling external corrosion through cathodic protection:
This item states requirements for what is required if a test point reading falls
below
criteria. Since the test stations are required in or near HCA’s and are rather
closely spaced, and with specific requirements on what do if the readings
fall
below criteria, the need for CIS is not justified.
This proposed requirement states that remediation must be completed
within 6-
months. This requirement is excessive and not justified. Based on the
seasons
and associated land use issues as well as the time it takes to obtain
permits, a
one-year timeframe is more appropriate.
WGP recommends changing 192.620(d)(8)(i) to read “… within one year…”.
This item requires a CIS after remediation for a CP issue. This requirement
is
excessive and not justified. The reason for a failed reading may not require
CIS to
confirm restoration of CP. Example include loss of power, a cable cut, a
short,
etc. all of which can be fixed and have no baring on the effectiveness of the
CP on
the segment. The operator does need to confirm that the remedial action
was
appropriate and effective, however CIS in not always necessary or may be
inappropriate.
WGP recommends changing 192.620(d)(8)(ii) to read “After remedial
action to
address the loss of CP, the operator must confirm that the remedial action
did
restore the CP system to criteria as identified in 192 subpart I”.
Item (9) – Conducting a baseline assessment of integrity:
This item requires the use of DA for segments that are not piggable. These
segments may be designed per 192.111 and therefore would not be
required to
follow the requirements of 192.620. In addition, DA may not be appropriate
for
periodic assessments at these locations. Previous waivers have allowed
operators
to develop a corrosion control plan that does not require DA but is entirely
appropriate for the subject segments.
Pressure testing is also an alternative to DA where ILI can not be
performed and
should be considered as an option as well
WGP recommends changing 192.620(d)(9)(iii) to read “…use either DA or
pressure testing to assess that segment or develop and implement a
corrosion
control plan to address corrosion of the segment”.
Item 10 – Conducting periodic assessments of integrity:
WGP agrees with the proposed requirements.
Item (11) – Making repairs:
Item 11(i) requires the use of the most conservative calculation for
determing
remaining strength. This statement seems to imply that more than one
calculation
must be performed. Each calculation method results in slightly different
answers
with none being more accurate than the other. This requirement is
excessive and
has not been justified.
The idea of tool tolerance is addressed in the Protocols used by PHMSA
for
expectations of an operator’s integrity management program. If Subpart O
is
referenced in lieu of this proposed requirement, there is no need for this
requirement.
Item 11(ii) in general, proposes that immediate repair conditions must be
replaced
based on the criteria set forth. These proposed requirements are extremely
conservative and in many cases are not achievable. These criteria are not
consistent with Subpart O requirements and have not been technically
justified.
These issues have been addressed in a White Paper “Safety Factors for
Assessing Pipeline Anomalies” (attached) which states that the
requirements
outlined in ASME B31.8S and incorporated into Subpart O of part 192 are
appropriate for pipelines operating up to 80% of SMYS.
Item 11(ii)(A) sets dent criteria to that required for new pipelines even if the
pipeline
is already in operation. For existing pipelines, this is not a readily achievable
requirement and is not technically justified. The requirements under 192.933
(d) are
the appropriate criteria to apply to existing pipelines
Item 11(iii) in general proposes that one year repair conditions must be
replaced
based on the criteria set forth. These proposed requirements are extremely
conservative and in many cases are not achievable. These criteria are not
consistent with Subpart O requirements and have not been technically
justified.
Again, these issues have been addressed in the White Paper “Safety
Factors for
Assessing Pipeline Anomalies”.
Early Special Permits required that any anomaly with a predicted failure
pressure
to MAOP ratio of 1.1 or less was an immediate repair condition. A one year
condition was an anomaly with a predicted failure pressure to MAOP ratio of
1.25
or less. Later Special Permits tightened these already conservative
requirements
by adding wall loss factors so that an immediate repair condition also
included any
wall loss of 60% or more and a one year condition included any wall loss of
40%
or more. These additional factors are not technically justified and add much
more
conservatism than is necessary.
Item 11(iv) is not clear. The terminology is not consistent with Subpart O
requirements in the regulations or ASME b31.8S. If an indication from an ILI
or DA
assessment does not require an examination or evaluation, it is not
determined to
be a defect. Based on the assessment information, the indications not
remediated
are classified and used to determine the next integrity assessment. This
paragraph seems to repeat the requirements of 10(i) of this paragraph yet
they
terminology or intent seems to conflict. Paragraph 10(i) is the appropriate
language to use to require subsequent inspections and references Subpart
O
where the requirements are more clearly stated.
WGP would prefer that paragraph 192.620(d)(11) as written be deleted in
its
entirety and replacing it with the statement “examination, evaluation and
remediation of any indication or anomaly must be in accordance with
Subpart O of
this part”. However some recognition for more conservative repair criteria
may be
justified for pipelines operating at the higher pressure levels.
WGP recommends modification of 192.620(d)11) to read as follows:
(i) Do the following when evaluating an anomaly:
(A) Use a method for determining remaining strength of a corroded
pipeline that is appropriate for the pipe being evaluated
(B) Take into account the tolerance of the tools used for the
assessment
(ii) Repair a defect immediately if any of the following apply:
(A) For new pipelines, a dent discovered during the baseline
assessment under (d)(9) of this section and the defect meets the criteria in
192.309(b). For existing pipelines, a dent discovered during the baseline
assessment under (d)(9) of this section and the defect meets the criteria in
192.933(d).
(B) The defect meets the criteria for immediate repair condition in
192.933(d)(1)(iii)
(C) A corrosion defect with a predicted failure pressure to MAOP
ratio
of 1.1 or less; or with pitting depths of 80% or more.
(iii) If paragraph (d)(ii) of this section does not require an immediate repair,
repair a
defect within one year of any of the following:
(A) The defect meets the criteria for a one-year condition in 192.933
(d)
(2)
(B) A corrosion defect with a predicted failure pressure to MAOP
ratio
of 1.25 or less; or with pitting depths of 70% of more.
The criteria as it relates to the predicted failure pressure to MAOP ratio will
address any issues of remaining strength of the pipeline. The pit depth
criteria will
address any issue with the potential for a corrosion leak. The 80% value for
immediate repair conditions is consistent with the various methodologies for
determining remaining strength of pipelines. Any corrosion with depths of
80% or
more is outside the parameters of the methodologies and provides
conservativeness. The 70% value for one-year repair conditions allows for
extreme
pitting corrosion over the one year period without exceeding the 80%
methodology
parameters.
Paragraph (e)
WGP agrees with the proposed requirements.
Attachment
This is comment on Rule
Pipeline Safety: Standards for Increasing the Maximum Allowable Operating Pressure for Gas Transmission Pipelines
View Comment
Attachments:
Williams Gas Pipeline - Comment
Title:
Williams Gas Pipeline - Comment
Related Comments
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May 19,2008 11:59 PM ET
Public Submission Posted: 06/11/2008 ID: PHMSA-2005-23447-0080
May 19,2008 11:59 PM ET