Carbon Steel Low Temperature Pipe Fittings

Solitaire Overseas supplies carbon steel low temperature pipe fittings in ASTM A420 Grade WPL6, Charpy V notch impact tested at minus 45 degrees Celsius (minus 50 degrees Fahrenheit) for service where standard WPB fittings would risk brittle fracture. Manufactured to ASME B16.9 and ASME B16.11 dimensions and compatible with ASTM A333 Grade 6 pipe and ASTM A350 LF2 flanges, these fittings are the standard choice for LNG terminals, cryogenic storage and cold climate pipelines. Every batch ships with a mill test certificate and impact test report confirming toughness at the specified design temperature.

Need the standard temperature counterpart for above ground sections of the same line? See our Carbon Steel Buttweld Fittings range, or contact our team about dual certified WPL6/WPB options.

Technical Data

Specifications Chemical Composition Mechanical Properties Grade Family Compatible Grades

Carbon Steel Low Temperature Pipe Fittings Specifications

Parameter	Specification
Standard	ASTM A420 Grade WPL6
Dimensional Standard	ASME B16.9, ASME B16.11
Size Range	NPS 1/2" to 48"
Wall Thickness	SCH 10 to XXS
Impact Test	-45°C (-50°F), Charpy V-notch
Compatible Pipe/Flange	ASTM A333 Gr. 6 pipe, ASTM A350 LF2 flanges, ASTM A320 Gr. L7 bolting
Hardness	197 HB max
Certification	Mill Test Certificate EN 10204 3.1 with impact test report

Chemical Composition (WPL6, %)

C max	Mn	P max	S max	Si	Ni max	Cr max	Mo max	Cu max
0.30	0.60 – 1.35	0.035	0.040	0.15 – 0.40	0.40	0.30	0.12	0.40

Mechanical Properties and Impact Requirements (WPL6)

Property	Requirement
Tensile Strength	415 – 655 MPa
Yield Strength min	240 MPa
Elongation min	22%
Impact Test Temperature	-45°C (-50°F)
Charpy V-notch, average of 3 specimens min	17.6 J (13 ft-lbf)
Charpy V-notch, single specimen min	13.6 J (10 ft-lbf)

ASTM A420 Grade Family by Impact Test Temperature (approximate, confirm against current ASTM A420 edition)

Grade	Typical Impact Test Temperature
WPL6	-45°C (-50°F) — most common grade, stocked by Solitaire Overseas
WPL9	-75°C (approx.)
WPL3	-100°C (approx.)
WPL8	-195°C (approx.) — cryogenic service

Compatible Pipe, Flange and Bolting Grades

Component	Compatible Grade
Pipe	ASTM A333 Grade 6 (seamless or welded)
Flange	ASTM A350 Grade LF2 Class 1
Bolting	ASTM A320 Grade L7 (low temperature)

Types of Carbon Steel Low Temperature Pipe Fittings

Elbows (45°, 90°) in WPL6 low temperature grade
Equal and Reducing Tees in WPL6
Concentric and Eccentric Reducers in WPL6
Caps and Crosses in WPL6

Applications of Carbon Steel Low Temperature Pipe Fittings

LNG plants
Cryogenic storage
Offshore arctic piping
Cold climate pipelines
Ethylene and propylene refrigeration systems
Nitrogen and industrial gas piping

WPL6 vs WPB - Which to Choose

ASTM A420 WPL6 and ASTM A234 WPB look similar on paper but are engineered for different temperature environments. Use this table to decide.

Criteria	ASTM A420 WPL6 (Low Temperature)	ASTM A234 WPB (Standard)
Impact Testing	Mandatory, Charpy V-notch at -45°C	Not required by default
Minimum Design Metal Temperature	Down to -46°C (-50°F)	Approximately -29°C (-20°F)
Maximum Service Temperature	Moderate, not intended for sustained high heat	Up to approximately 425-480°C before graphitization risk
Typical Use Case	LNG, cryogenic, cold climate piping	General moderate to high temperature process piping
Learn More	This page	Carbon Steel Buttweld Fittings

Frequently Asked Questions

Q: What is the minimum design temperature for WPL6 fittings?

A: ASTM A420 WPL6 fittings are impact tested at -45°C (-50°F), making them suitable for minimum design metal temperatures down to that level; colder services require higher grades such as WPL8 or WPL9.

Q: Can WPL6 fittings be dual certified with WPB?

A: Yes, many manufacturers including Solitaire Overseas can supply fittings dual certified to both ASTM A420 WPL6 and ASTM A234 WPB where the chemistry and mechanical properties satisfy both specifications.

Q: What documentation should I expect for low temperature fittings?

A: Along with the standard mill test certificate, low temperature orders should include a Charpy V-notch impact test report confirming compliance at the specified design temperature.

Q: What is the difference between WPL6 and WPL3, WPL8 or WPL9?

A: All are low temperature grades under ASTM A420, but each is qualified to a different minimum impact test temperature; WPL6 is tested at -45°C and is the most commonly stocked grade, while WPL3, WPL8 and WPL9 are qualified for progressively more extreme cryogenic temperatures.

Q: What flange and bolting grades pair with WPL6 fittings?

A: WPL6 fittings are typically paired with ASTM A350 Grade LF2 flanges and ASTM A320 Grade L7 low temperature bolting to maintain consistent toughness across the joint.

Q: Is post weld heat treatment required for WPL6 fittings?

A: Post weld heat treatment is commonly specified for WPL6 field welds, typically in the range of 595°C to 650°C, to relieve residual stress; confirm the requirement against your governing piping code.