LSAW vs DSAW vs SSAW

LSAW, DSAW, and SSAW are three submerged arc welded (SAW) pipe types used for large-diameter applications. Each differs in weld orientation, manufacturing process, and suitability for specific services.

LSAW (Longitudinal SAW) has a single straight seam along the pipe length. DSAW (Double SAW) is essentially LSAW with both internal and external weld passes (the term is sometimes used interchangeably with LSAW). SSAW (Spiral SAW) has a helical seam formed by spirally winding steel strip.

Comparison Table

Feature	LSAW	DSAW	SSAW
Weld orientation	Longitudinal (straight)	Longitudinal (straight)	Helical (spiral)
Weld passes	1 or 2 (ID + OD)	2 (always ID + OD)	2 (ID + OD)
Raw material	Discrete steel plates	Discrete steel plates	Continuous steel coil/strip
Forming method	UOE, JCOE, roll-bend	UOE, JCOE	Spiral forming
Size range (OD)	406-1524 mm	406-1524 mm	219-3500 mm
Wall thickness	6-40+ mm	6-40+ mm	5-25 mm
Max grade	API 5L X80+	API 5L X80+	API 5L X70
Weld length per meter	1 m	1 m	1.1-3+ m (depends on helix angle)
Pressure suitability	High	High	Moderate
Cost	Highest	Highest	Lowest
Production speed	Moderate	Moderate	Fast

LSAW and DSAW

In practice, LSAW and DSAW refer to the same product. The “double” in DSAW emphasizes that both inside and outside weld passes are made by submerged arc welding. Most modern LSAW production uses two SAW passes, so the terms overlap. API 5L does not distinguish between them; it classifies both as “SAW with longitudinal seam.”

LSAW/DSAW pipe is the standard for:

• High-pressure oil and gas transmission pipelines
• Offshore pipelines and risers
• Sour service pipelines (with HIC/SSC testing per NACE)
• Applications requiring high-strength grades (X65, X70, X80)

SSAW (Spiral Welded)

SSAW pipe is formed by helically winding a steel strip and welding the spiral seam. It can produce very large diameters (up to 3500 mm) from relatively narrow coil stock, which keeps costs down.

However, the longer weld seam per unit length and the stress orientation (weld crosses the hoop stress direction at an angle) limit SSAW to lower-pressure services:

• Water transmission and distribution
• Low-pressure gas distribution
• Structural piling and casing
• Culverts and drainage

Common Mistake

SSAW pipe should not be substituted for LSAW in high-pressure hydrocarbon service unless explicitly approved by the design code and project specification. The helical weld geometry complicates in-line inspection and integrity assessment.

Cost Ranking

From lowest to highest unit cost for equivalent diameter: SSAW < LSAW/DSAW < Seamless. On large pipeline projects, material cost differences between LSAW and SSAW can reach 15-30%, but pressure and code requirements typically dictate the choice rather than price alone.

Read the full guide to pipe types