TENSILE TESTING OF CARBON STEEL IN HIGH PRESSURE HYDROGEN Page: 3 of 8
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WSRC-STI-2007-00211
inadequate for stress analysis in structural integrity-related
issues3. In addition, the data did not address the specific steels
of interest for piping systems or the effect of hydrogen on
welded regions and heat affected zones (HAZ's).
The tensile and fatigue properties have been obtained in
1000 psig (6.9 MPa) hydrogen environment for some API
pipeline materials5 (X42 and X70) and low carbon steels (A516
and A106B) and were reported by Cialone and Holbrook6, as
well as other studies'8. The tensile results from these reports
are consolidated in Table I. The yield stress and UTS do not
reveal any consistent trends when comparing the specimens
tested in air with those tested in hydrogen. In most cases, a
slight reduction in elongation was noted when the steel
specimens were tested in 6.9 MPa hydrogen. However, in
every case the reduction of area (RA) measured showed a slight
decline in hydrogen.
Table I: Tensile properties for X42, X70, A516, and A106B
in air and in 6.9 MPa (1000 psi) hydrogen gas (shaded)6.
Steel Environ. 0.2% UTS ElongA Reduction
Yield MPa % of Area
MPa
X427 Air 366 511 21 56
Long.
6.9 MPa H 331 483 20 44
X427 Air 311 490 21 52
Trans.
6.9 MPa H2 338 476 19 41
X706 Air 584 669 20 57
Long.
6.9 MPa H 548 659 20 47
X706 Air 613 702 19 53
Trans.
6.9 MPa H2 593 686 15 38
A516 Air 372 538 17 70
8
6.9 MPa H2 365 552 20 43
A106 Air 462 558 14 58
B 8
6.9 MPa H 503 579 11 50
________ ___________ _________ _________ ___________AElongation % was reported for a
1" (25.4 mm) gage length
The present work summarizes continued study in this
area in order to collect a data set large enough to determine
the effect of hydrogen on properties in a method that is
statistically valid and quantitative. Furthermore, this
database will provide not only properties but the entire the
entire stress-strain curve for a material. Hence, the need
for continued testing of this class of steels in hydrogen
environments is still present. This has prompted a renewed
interest in testing these materials in hydrogen
environments. Tensile testing of carbon steel in hydrogenatmospheres (up to 10.3 MPa or 1500 psi) was planned to
develop a data set for transmission pipelines. Of alloys
initially considered, ASTM A106 grade B was chosen
because of its wide utilization in the pipeline industry. The
compositional requirements for this steel are listed in Table
II. The pipe section was chosen because the available wall
thickness left ample material for the machining of
specimens and could be sectioned with the entire gage
section intersecting the base metal, weld metal or HAZ.
This paper documents the results from the tensile tests of
specimens machined from this welded pipe section.
Table II: Alloy Composition and Tensile Properties for
A 106 Grade B Pipe Material9A For each reduction of 0.01% below the specified carbon
maximum, an increase of 0.06% manganese above the
specified maximum will be permitted up to a maximum of
1.35%.
B These five elements combined shall not exceed 1%.
EXPERIM ENTAL
A section of 4 inch pipe (4.5 inches OD X 0.674
inches wall thickness) was circumferentially welded using
welding procedure specification WPS-P1-TA. The multi-
pass SMAW weld was performed with certification and without
any post weld heat treatment (PWHT). In this specification, no
PWHT is required unless lines are intended for caustic service
or wall thickness is > 19 mm (i.e., 0.75 inches). The root pass
of the weld was performed by gas tungsten arc welding
t This site specific procedure specification was qualified to the ASME
Boiler and Pressure Vessel Code, Section IX, "Welding and Brazing
Qualifications"2
A 106 Grade B
Element/Property Composition, %
Carbon, maxA 0.3
Manganese 0.29-1.06
Phosphorus, max 0.035
Sulfur, max 0.035
Silicon, min 0.10
Chrome, maxB 0.40
Copper, maxB 0.40
Molybdenum, 0.15
maxB
Nickel, maxB 0.40
Vanadium, maxB 0.08
0.2% Yield Stress 240
(MPa)
Ultimate Tensile 400
Stress (MPa)
Elongation (%) for 30 (16.5 trans.)
50 mm gage length
Reduction in Area N/A
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Duncan, A; Thad Adams, T & Ps Lam, P. TENSILE TESTING OF CARBON STEEL IN HIGH PRESSURE HYDROGEN, article, May 2, 2007; [Aiken, South Carolina]. (https://digital.library.unt.edu/ark:/67531/metadc882823/m1/3/: accessed April 19, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.