ERW Pipe Standards, Size Range & Grades

The full form of ERW pipe is "Electric Resistance Welded pipe." In the steel pipe industry, ERW steel pipe means a straight seam pipe made through electric resistance welding — a fast, low-cost welding process used to move oil, natural gas, and other pressurized fluids.

ERW pipe starts as a hot-rolled steel coil. A forming machine bends it into a round shape. Then high-frequency current heats the two edges of the steel using what's called the skin effect and proximity effect — this concentrates heat right where the edges meet. Extrusion rollers press the hot edges together to form the weld. Because the weld comes from melting the steel strip's own material (not filler metal), the seam ends up stronger than in ordinary welded pipe.

That combination — fast, automated, low-cost welding — is why ERW steel pipe shows up across so many industries: aviation, energy, automotive, construction, and general fluid transport.

1. ERW Pipe Standards, Size Range & Grades

1.1 ERW Pipe Size Range

The weld seam sets a practical ceiling on size. Conventional ERW pipe tops out around 24" (609mm) outside diameter. Past that point, coil-forming and induction welding get impractical, so manufacturers switch to the SAW (submerged arc welding) process instead.

1.2 Common Standards for ERW Pipe

Within that size range, ERW pipe is made to a number of standards, depending on the material and the job:

Carbon steel ERW pipe standards:
ASTM A53 Type E (electric resistance welded)
ASTM A252 pile pipe
ASTM A500 structural tubing
ASTM A134 and ASTM A135 pipe
EN 10219 S275, S355 pipe

Stainless steel ERW pipe standards:
ASTM A269 stainless steel pipe
ASTM A270 sanitary tubing
ASTM A312 stainless steel pipe
ASTM A790 ferritic/austenitic/duplex stainless pipe

API ERW pipe standards:
API 5L Grade B to X70, PSL1 (PSL2 grade must be made via the HFW process)
API 5CT J55/K55, N80 casing and tubing

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