The ERW Welding Process
API 5L, ASTM A53, ASTM A178, and ASTM A500 resistance welded pipes utilize a filler-free pressure welding process, where no additional material is added to the weld seam. High-frequency current's skin effect and proximity effect instantly heat the strip edges to welding temperature, followed by compression via squeeze rollers to form a forged microstructure in the weld zone. For high-quality steel pipes, heat treatment, online or offline, is applied along the weld line to refine the weld zone microstructure, and premium ERW pipes achieve equivalent toughness in the weld seam as the base material.
Specification Range
Outside diameters range from 4 to 20 inches, wall thicknesses from 3 to 20 mm, and lengths from 3 to 12 m or per customer requirement. Ends are plain, beveled, or threaded. Applicable standards include API 5L, ASTM A53, A178, A500 and A501, A691, A252, A672, and EN 10217.
Surface and Packing Options
Surfaces include lightly oiled, hot-dip galvanized, electro-galvanized, black, bare, varnish or anti-rust oil, and protective coatings such as coal tar epoxy, fusion bonded epoxy, and three-layer polyethylene. Packing uses plastic plugs in both ends, hexagonal bundles of up to 2000 kg with steel strips, waterproof paper wrapping, PVC sleeves, sackcloth, and plastic caps.
Testing Requirements
Testing includes chemical composition analysis; mechanical properties such as ultimate tensile strength, yield strength, and elongation; technical properties such as flattening, bending, hardness, and impact tests; exterior size inspection; hydrostatic testing; and non-destructive testing including eddy current, radiographic, and ultrasonic examination.
Applications
ERW pipe serves line pipe service under API 5L, general plumbing and mechanical service under A53, boiler and heat exchanger tubing under A178, and structural hollow sections under A500, plus coated line pipe applications under the coating-related standards.
Frequently Asked Questions
Q: What is the ERW welding process?
A: Filler-free pressure welding where high-frequency current heats strip edges and squeeze rollers forge them together.
Q: What is the size range?
A: OD 4 to 20 inches, wall 3 to 20 mm, length 3 to 12 m.
Q: What standards apply?
A: API 5L, ASTM A53, A178, A500, A501, A691, A252, A672, and EN 10217.
Q: What coatings are available?
A: FBE, 3-layer PE, coal tar epoxy, galvanizing, and varnish.
Q: What NDT is applied?
A: Eddy current, radiographic, and ultrasonic examination.
Q: Can the weld match base metal toughness?
A: Yes, with inline or offline weld-line heat treatment in premium production.
For ERW steel pipe quotations with your required standard and size, contact our sales team.
