ERW Pipe Thickness Chart

What is ERW pipe?
ERW (Electric Resistance Welded) pipe, also known as high-frequency resistance welded steel pipe, is a steel pipe formed by continuous forming of cold-rolled steel strip (coil), using the skin effect and proximity effect of high-frequency current to heat the edge of the steel plate, and welding it under pressure.

Core technology: 
No welding wire is required, relying on the melting of the metal itself to achieve seamless welding, high production efficiency and low cost.

ERW Pipe Wall Thickness Size Chart:

ERW pipe wall thickness selection basis:

1. Select by purpose
Low-pressure water pipe/gas: ASTM A53 SCH 40
Typical wall thickness range: 2.77mm~8.18mm

Oil/gas transmission: API 5L B
Typical wall thickness range: 3.91mm~12.70mm

High-pressure industrial pipeline: API 5L X42/X52
Typical wall thickness range: 6.0mm~15.0mm

Building, bridge, mechanical structure pipe: ASTM A500 ERW (cold-formed welded carbon steel structure pipe)
Typical wall thickness range (round pipe): 1.0mm~22.0mm; outer diameter: 21.3mm ~ 660mm.

Building scaffolding: GB/T 3091
Typical wall thickness range: 2.0mm~4.0mm

2. Select by pressure level
Low pressure (PN≤1.6MPa): wall thickness ≥2.5mm (such as DN50×3.0mm)
Medium pressure (PN≤4.0MPa): wall thickness ≥5.0mm (such as DN150×7.11mm)
High pressure (PN≥10MPa): wall thickness ≥10mm (such as DN300×12.7mm)

3. Wall thickness calculation formula
For ERW pipes that need to bear pressure, ASME B31.3 Formula to estimate minimum wall thickness:

t=2×(S×E+P×Y)P×D

P: design pressure (MPa)
D: outer diameter (mm)
S: allowable material stress (MPa)
E: weld coefficient (0.85~0.95 for ERW pipe)
Y: temperature correction factor (0.4~0.7)

ERW pipe wall thickness tolerance:

API 5L wall thickness tolerance: +15% / -12.5%
ASTM A53 wall thickness tolerance: ±10%
GB/T 3091 wall thickness tolerance: ±10% (DN≤100mm); ±7.5% (DN＞100mm).

FAQ:

Q1: What is the difference in wall thickness between ERW pipe and seamless pipe?
→ Under the same specification, the wall thickness of ERW pipe is more uniform (controlled by cold rolling process), but seamless pipe can produce thicker wall (such as SCH 160).

Q2: Does the wall thickness of galvanized ERW pipe need to be increased?
→ No, the effect of the galvanized layer (50~100μm) on strength can be ignored, but attention should be paid to the adhesion of the zinc layer.

Q3: How to detect the wall thickness of ERW pipe?
→ Ultrasonic thickness gauge (UT) or caliper measurement (avoid the weld area).

Q4: Can ERW pipe replace seamless pipe?
→ Yes, but it must meet the following conditions:
Pressure ≤10MPa and no severe impact (such as seamless pipes required for hydraulic systems).
Ensure the quality of welds through UT testing.

Q5: Can ASTM A500 ERW pipe be used for pressure fluid transportation?
→ Not recommended, fluid pipe standards such as ASTM A53 or API 5L should be selected.

Q6: What are the differences in mechanical properties between square pipes and round pipes?
→ At the same level, round pipes have better torsion resistance, and square pipes have better bending resistance (cold work hardening effect at corners).

Q7: Difference between A500 ERW and A53 ERW
ASTM A500 is designed for structural design (non-fluid transportation), emphasizing mechanical properties and cross-sectional shape tolerance.
ASTM A53 is mainly used in high-pressure systems in the fields of construction, machinery, and automobiles. The design uses cover stress-bearing structural parts and general industrial pipeline systems, and are suitable for conveying non-corrosive media such as steam, water, gas, and air.

In short, through reasonable selection, ERW pipelines can take into account both economy and performance, and are suitable for most medium and low pressure scenarios.

Read more: Carbon steel ERW pipe grade and specification or ERW pipe vs Seamless pipe cost