Alloy 20 Welded Pipes

Alloy 20 welded pipes have become an indispensable baseline infrastructure component across global heavy industries. Our manufacturers can produce seamless and welded pipes to meet industry requirements. Contact us market@htpipe.com for more information and a free quote!

2.4660 Tube Specification

Specification	ASTM B729, ASME SB 729, ASTM B468, ASME SB 468
Standard	GB, EN, DIN, DS, DTD, ASTM, SAE, ASME, AISI, JIS, TOCT, NF, AMS
Alloy 20 Tube Tolerances	+/- 0.030; tolerance may vary depending on grade and thickness
Seamless Tube Size	15 NB to 150 NB IN 1/2" OD - 12" OD
Welded Tube Size	1/2" OD - 12" OD Guage: 25 SWG - 10 SWG
Length	Upto 30 meters, Single Random, Double Random & Required Length End: Plain End, Beveled End, Treaded, or Custom Cut Lengths
WT	0.40 mm - 12.70 mm
Schedule	5, 10S, 10, 30, 40S, 40, 80, 80S, XS, 160, XXH
Swg & Bwg	10 Swg., 12 Swg., 14 Swg., 16 Swg., 18 Swg., 20 Swg.
Manufacturing Techniques	EFW, CDW, ERW, LSAW, DOM, Fabricated, Seam-Welded, Seamless, CEW, Redrawn, Welded

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Manufacturing Standards

High-quality Alloy 20 welded pipes are manufactured strictly under ASTM B464 (covering longitudinal flash-welded or electric-resistance-welded pipes) and ASME SB464 parameters. These specifications enforce rigorous hydrostatic testing, non-destructive eddy-current or ultrasonic testing, and precise dimensional calibrations across schedules (commonly Schedule 10S and 40S).

 

Carpenter 20 Chemical Composition

Grade	Ni	C	Mn	P	S	Si	Cr	Nb	Mo	Cu
Alloy 20	32 - 38	0.02 max	1 - 2	0.02 max	0.005 max	0.7 max	19 - 21	0.1 - 0.3	2 - 3	3 - 4

 

Mechanical Properties Of Alloy 20 Tubing

Grade	Density	Melting Point	Tensile Strength	Yield Strength (0.2%Offset)	Elongation
Alloy 20	8.1 g/cm3	1443 °C (2430 °F)	Psi -80,000, MPa -551	Psi - 35,000, MPa - 241	30 %

 

Fabrication, Welding, and Installation Best Practices

Welding Alloy 20 requires a solid understanding of its thermal properties to maintain its corrosion resistance.

Achieving Sound Welds

Because it is a fully austenitic alloy, Alloy 20 is susceptible to hot cracking if the heat input is managed poorly.

Filler Material Selection: Always match the pipe with low-carbon, over-alloyed fillers such as ER320LR for TIG/MIG welding, or E320LR for shielded metal arc welding (SMAW). The "LR" stands for low residual elements, which helps minimize the risk of micro-fissuring.

Heat Control Strategy: Keep interpass temperatures low-ideally under 250°F (121°C). Avoid weaving the torch; use straight, fast stringer beads to keep thermal input minimal.

Joint Preparation: Ensure the joint faces are completely free of oil, grease, or zinc markings before striking the arc, as contaminants can compromise the weld's integrity.

 

Alloy 20 vs. 316 Stainless Steel

Many facilities default to 316L stainless steel due to initial cost calculations, only to suffer rapid system failure when chemical concentrations shift. The structural differences between the two materials highlight why upgrading is often necessary.

 

Sulfuric Acid Limits: 316 stainless steel degrades quickly when exposed to mid-range sulfuric acid concentrations (20% to 40%), especially if temperatures rise. Alloy 20 remains remarkably stable across the entire concentration spectrum up to roughly 150°F (65°C).

 

Risk of Hydrogen Gas Exploitation: When standard steels react with volatile, weak acids, they can generate hydrogen gas pockets. Alloy 20's passive surface prevents this dangerous chemical reaction.

 

Total Lifecycle Economics: While an Alloy 20 welded pipe carries a higher initial material cost, it eliminates the repeated downtime, labor charges, and replacement costs tied to accelerated steel degradation.

 

 

 

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