Longitudinal Submerged Arc Welded Line Pipe
Longitudinal submerged arc welded (LSAW) line pipe is an industrial piping product manufactured from grades such as X42, X46, X52, X56, X70 and their L-series equivalents. This product is utilized in oil and natural gas transmission, urban pipeline networks, building structures and hydraulic engineering projects, conveying media including water, coal gas and liquefied petroleum gas (LPG).
Manufacturing Process
LSAW pipe is formed from heavy steel plate by JCOE or UOE forming, followed by submerged arc welding on both the internal and external longitudinal seams. The double-sided weld provides full penetration and high joint quality, making LSAW the preferred route for large diameters and thick walls where ERW capacity is insufficient.
Specification Summary
| Parameter | Range / Option |
|---|---|
| Standards | API 5L PSL1/PSL2, API 5CT, API 2B, ASTM A53/A252/A671/A672, DIN 2458, IS 3589, EN 10217, EN 10219-1, EN 10224, SY/T 5037, JIS G3444, GB/T 3091, GB/T 9711.1/.2 |
| Grades | API 5L GR A, GR B, L235–L355, X42, X46, X56, X60, X65, X70; API 2B 2H/2W; ASTM A252 GR2/GR3; EN S275–S355; JIS STK400/STK500/SS400 |
| Outer diameter | 457.2–1422.2 mm (18"–56") |
| Wall thickness | 7.92–50.8 mm (0.312"–2") |
| Length | 3–12.3 m |
Testing Requirements
Every LSAW pipe is verified by chemical component analysis, mechanical properties (tensile, yield, elongation), metallographic examination, bend and Charpy V-notch impact tests, DWTT, flattening and blow tests, X-ray examination of the weld, exterior size inspection, ultrasonic testing and hydrostatic testing.
Surface Treatment Options
Depending on the project specification, LSAW pipes can be supplied with fusion-bonded epoxy (FBE), coal tar epoxy, 3PE, varnish, bitumen or black oil coating for corrosion protection in buried and marine service.
Frequently Asked Questions
What is the difference between LSAW and SSAW?
LSAW has a single longitudinal weld seam and is formed from plate; SSAW has a spiral weld and is formed from coil. LSAW generally offers better dimensional control for thick walls.
Why choose LSAW for large diameters?
LSAW can achieve diameters from 18" to 56" with wall thicknesses up to 50.8 mm, covering high-pressure trunk line requirements that exceed ERW capability.
Which grades are available in LSAW?
API 5L grades A, B, X42 through X70 and their L-series, plus structural and piling grades to ASTM, EN, JIS and GB standards.
Is 100% weld inspection required?
Yes. X-ray or ultrasonic examination of the full longitudinal weld seam is standard for PSL2 and for high-integrity projects.
Can LSAW pipe be 3PE coated?
Yes. 3PE, FBE, coal tar epoxy and other coatings are applied per project specification for buried service.
What tests prove LSAW quality?
Hydrostatic testing, tensile and Charpy tests, DWTT, flattening, X-ray and UT of welds, plus dimensional and surface inspection.
