ASTM A312 254SMO Large-Diameter Welded Pipe

ASTM A312 254SMO Large-Diameter Welded Pipe is an austenitic stainless steel welded pipe made from UNS S31254 (254SMO). Its chemical composition contains approximately 6% molybdenum, 20% chromium, and 18% nickel, significantly enhancing its resistance to pitting and crevice corrosion. The PREN (Pitting Resistance Equivalent Number) typically exceeds 40, making it particularly suitable for high-chloride environments such as seawater desalination, chemical processing, and flue gas desulfurization (FGD) systems.

 

ASTM A312 254SMO large-diameter welded pipes are manufactured using automated welding processes such as TIG or laser welding. They generally refer to pipes with an outer diameter greater than 152 mm (6 inches), and GNEE Stainless Steel can supply welded pipes with sizes up to 1219 mm (48 inches). After welding, solution annealing treatment (1150–1200°C followed by rapid cooling) is required to restore corrosion resistance and mechanical properties. Eddy current testing (ECT) or ultrasonic testing (UT) is applied to ensure weld integrity.

 

 

Surface finishes can be pickled, sandblasted, or bright annealed, while end types include plain end (BE) and beveled end (PE). In addition, GNEE provides matching ERNiCrMo-3 welding consumables and technical guidance for post-weld solution heat treatment, ensuring reliable installation and long-term performance in engineering applications.

 

ASTM A312 Alloy 254 Welded Pipes Specification

roduct Name	ASTM A312 Alloy 254 Stainless Steel Welded Pipes
Material	254SMO
Standard	ASTM A312/A358 etc
Welding Line Type	EFW / ERW / PAW /GTAW
Specification	Outer diameter	168mm-1828mm DN150-1800 6nch -72 inch
	Wall thickness	3mm-60mm SCH5s, SCH10S ,SCH10 ,SCH20, SCH30, SCH40s, SCH STD, SCH40, SCH60, SCH80s, SCH XS, SCH100, SCH120, SCH140, SCH160, SCHXXS
	Length	6M,12M or as customer's actual request
Surface	Annealing&Pickling, Polishing (180#-600#), Bright Annealing, Sand Blasting,Shot Blasting
RT(X-Ray) Inspection	100% filming Class 1 / 2 / 3/ 4/ 5
Delivery Time	1.for ready stock :7 days after receiving the deposit of T/T 2.For MTO: 35 days after receiving the deposit of T/T
Trade Terms	EXW,FOB, CFR, CIF etc.

 

S31254 stainless steel welded Pipes Chemical Composition

SMO 254	Ni	C	Mo	Mn	Si	Fe	Cu	S	P	Cr
	17.5 – 18.5	0.02 max	6 – 6.5	1 max	0.8 max	–	0.5 – 1	0.01 max	0.03 max	19.5 – 20.5

 

SMO 254 Stainless Steel Pipe Mechanical Properties

Density	Melting Point	Yield Strength (0.2%Offset)	Tensile Strength	Elongation
8.0 g/cm3	1320-1390 ℃	300	650	35 %

 

ASTM A312 Standard Dimensional Tolerance

Standard	Outside Diameter Tolerance(mm)		Thickness Tolerance(mm)		Length Tolerance (mm)
ASTM A312	[10.29~48.26]	+0.4 / -0.8	10.3~73	+20% / -12.5%	+6 / -0
			88.9~457 T/D≤5%	+22.5%/-12.5%
	(48.26~114.30]	±0.80	88.9~457 T/D>5%	+15%/-12.5%
	(114.30~219.08]	+1.6 / -0.8	508above T/D<5%	+22.5%/-12.5%
	(219.08~457.20]	+2.4 / -0.8	508above T/D>5%	+15%/-12.5%

 

large-diameter 254SMO pipes application

Desalination Plants: Handling high-concentration brine.
Offshore Oil & Gas: Seawater cooling systems and firewater mains.
Pulp & Paper: Bleaching plants where high levels of chlorides and chlorine dioxide are present.
Flue Gas Desulfurization (FGD): Scrubbers in power plants.

 

 

What is the difference between ASTM A312 254SMO and 316L?

ASTM A312 254SMO (UNS S31254) is a super austenitic stainless steel with a significantly higher alloy content compared to 316L. In contrast, 316L contains only about 2% to 3% molybdenum and is typically used in moderately corrosive environments.

254SMO is widely applied in extremely harsh conditions such as seawater desalination plants and offshore oil and gas production, where high resistance to pitting, crevice corrosion, and chloride-induced corrosion is required. In comparison, 316L is commonly used in marine engineering, pharmaceuticals, and food processing industries due to its good overall corrosion resistance and cost-effectiveness.

 

 

ASTM A312 254SMO Large-Diameter Welded Pipe Price

The price of ASTM A312 254SMO (UNS S31254) large-diameter welded pipe typically ranges from $2,400 to over $20,000 per metric ton-or $7.60 to over $50 per kilogram-for high-performance, large-diameter industrial piping applications; the specific price depends on the pipe wall thickness and the particular requirements regarding high corrosion resistance.

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Testing & Certification

Hydrostatic Testing: Pressure-tested to 1.5× working pressure to ensure leak-free performance.

Non-Destructive Testing (NDT): Eddy current, ultrasonic (UT), or liquid penetrant inspection for defect detection.

Chemical Analysis: Verified via optical emission spectrometry (OES) or X-ray fluorescence (XRF).

Mechanical Testing: Tensile, hardness (HV), and flattening tests for quality validation.

Certifications: GB/T14976-compliant Mill Test Reports (MTRs), ISO 9001, and CE documentation.

 

High-Quality Packaging

ASTM A312 254SMO large-diameter welded pipes are protected by reinforced, export-grade packaging designed to ensure zero deformation during long-distance transit. Each pipe is wrapped in an anti-corrosion protective layer, fitted with end caps, and covered with moisture-proof materials; the pipes are then secured within steel frames or fumigated wooden crates. This packaging system is suitable for pipes with an outer diameter of up to 1219 mm.