Hydrocarbon Processing - June 2021 - GP-18

SPECIAL FOCUS: PIPELINES AND TRANSPORT
Pipe produced by capable, reputable
mills that is based on applicable codes
and specifications should be subject to
factual evaluation. The mill's experience
in the production of each type of pipe
must be requested and validated.
Comparison of ERW and DSAW/LSAW pipes. The author
believes there is no general single option for pipe type (i.e.,
ERW vs. DSAW/LSAW) for use in large (> 16 nominal pipe
size, or NPS) onshore gas pipelines that is correct and applicable
for every application. Detailed study is needed based on
the project constrains (i.e., costs, schedule, etc.), pipeline terrain,
pipe specifications (e.g., grade, thickness, etc.), quality requirements,
risks, pipe manufacturer's experience, client's pipe
integrity experience, etc.
TABLE 1 gives a general comparison between ERW and
DSAW/LSAW pipes for sizes above 16 in. onshore buried gas
pipelines, based on the author's experience.
Proposed selection criteria. The selection between ERW
and DSAW/LSAW pipes in a pipeline project requires detailed
study, especially with regard to the mill's capability and experience.
The author proposes the following steps for making a
decision between ERW and DSAW/LSAW pipes:
1. Finalize critical operating and design parameters of the
pipeline system, such as pressure, temperature, flowrate,
minimum design metal temperature (MDMT), etc.
2. Conduct a reliable fracture control analysis based on
the rich gas composition of the gas. The Battelle TwoCurve
Method is a classic method that may be used.
3. Finalize the pipe grade, toughness and MDMT.
4. List the project constrains, including costs, schedule,
quality, resources, risks, customer experience and
preference, etc.
5. Conduct a market study and identify and manage
the associated risks.
6. Decide on potential mills for the pipe manufacture
and request their workload, past experience,
production processes for different types of pipe,
optional tests and inspections, etc.
7. Determine the evaluating parameters and
associated weights.
8. Prepare a pipe datasheet based on two options
(ERW and DSAW/LSAW) and send the datasheet
with a material requisition to the potential mills.
9. As part of the quote for supply of line pipe, ask the
manufacturer to submit a manufacturing procedure
specification (MPS) document providing information
on raw material, production process, inspection,
test, etc. in detail.
10. Review the mill's quote and prepare technical and
commercial evaluations in a bias-free atmosphere.
Clarify unclear areas with the mills and a subject
matter expert.
18 MAY/JUNE 2021 | GasProcessingNews.com
11. Consider a brainstorming session and ask for feedback
from construction, the pipeline integrity team,
shop inspectors, etc.
12. Conduct a cost-benefit analysis by considering
the cost of risk and all key factors, rather than just
the pipe cost quoted by the mills.
Recommendations. Many factors and risks must be considered
in the selection of the final pipe type (between ERW and
DSAW/LSAW) for an onshore buried natural gas pipeline
project, based on the actual project requirements and conditions.
The project manager should ensure that a bias-free engineering
study has been conducted.
The author's conclusion is that for a pipe size of 16
in.-26 in., both ERW and SAW pipes are possible options for
an onshore buried natural gas pipeline project. A final decision
must be made based on a detailed study considering many factors
besides the pipe cost. If a pipe longitudinal fails during
operation, then the root causes, direct causes and contributing
causes must be discerned.
The author believes that pipe produced by capable, reputable
mills that is based on applicable codes, standards and
specifications should be subject to factual evaluation and not
personal judgment. The mill's experience in the production of
each type of pipe in similar service, thickness, size and grade
must be requested and validated. Engineers must ask for manufacturing
procedure qualification testing (MPQT), manufacturing
procedure specifications (MPS) and other standards.
Finally, continual advances
in materials and welding
techniques have resulted in dramatic improvements in the
reliability of both ERW and DSAW/LSAW pipes. For highpressure
applications with design pressure of ≥ 100 barg, the
author prefers DSAW/LSAW pipes, as discussed in the last
row of TABLE 1.
Regardless of which type is selected, the risks of corrosion,
fatigue and seam-related defects to the longitudinal weld
seams of ERW and DSAW/LSAW pipes still exist. These defects
should be monitored and identified through integrity
assessments (e.g., hydrostatic tests, indirect assessments and
direct assessments) and must be repaired when found. GP
LITERATURE CITED
1
2
Limon, S. and D. Katz, " A ERW seam weld failure, " Paper No. 08150, NACE
International Corrosion Conference and Expo, 2008.
U.S. National Transportation Safety Board, " Pipeline accident report: Rupture of
Enbridge Pipeline and release of crude oil near Cohasset, Minnesota, July 4, 2002 "
NTSB/PAR-04/01, June 23, 2004.
3 JFE Steel Corp., Line Pipe Catalog No. E1E-001-05.
4
1, 2011, Online:
FSPipeManufacturingProcess.htm
5 JFE Steel Corp., Technical Report No. 18, March 2013.
SHAHAB ZARDYNEZHAD is a registered senior mechanical/
pipeline engineer in Alberta with more than 29 yr of experience
working in the world's largest oil, gas and petrochemical
projects. He has experience in many cross-country, longdistance
pipeline projects including buried, aboveground,
thermal, high-pressure, NGL and sour gas pipelines. He holds a
BS degree in mechanical engineering from the University of
Petroleum of Iran, an MS degree in industrial engineering from IUST Iran and MS
degrees in project management and mechanical engineering (pipeline
specialization) from the University of Calgary in Canada.
U.S. Department of Transportation, Pipeline & Hazardous Materials Safety
Administration,
" Fact sheet: Pipe manufacturing process, " December
https://primis.phmsa.dot.gov/comm/FactSheets/
https://primis.phmsa.dot.gov/comm/FactSheets/FSPipeManufacturingProcess.htm https://primis.phmsa.dot.gov/comm/FactSheets/FSPipeManufacturingProcess.htm http://www.GasProcessingNews.com
Hydrocarbon Processing - June 2021

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