ERW Pipe Thickness Chart & Sizing Guide

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 hot-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 a high-integrity weld, offering high production efficiency and low cost.

ERW (electric resistance welded) pipes & tubes are available in a wide range of sizes, typically from 1/2" to 24" in diameter. The wall thickness of these pipes varies, with common thicknesses ranging from 2mm to 12.7mm.

ERW Steel Pipe Dimensions & Wall Thickness Chart (NPS) – Quick Reference

This table only lists the commonly used wall thickness grades (STD / Sch 40, XS / Sch 80) for carbon steel ERW pipes, suitable for quick selection or preliminary design reference. For wall thickness data from Sch 10 to XXS, please refer to the "Complete Dimension Table" below.

ERW Carbon Steel Pipe Schedule & Dimensions (ASME B36.10M)

This table provides wall thickness data for the entire range of carbon steel pipes (applicable to ERW and seamless) from Sch 10 to XXS, based on ASME B36.10M, suitable for detailed engineering design or specification verification. For quick reference of commonly used wall thicknesses, please refer to the quick lookup table above.

DN	NPS	Wall Thickness (mm)	Sch 10	Sch 20	Sch 30	Sch 40 / STD	Sch 60	Sch 80 / XS	Sch 100	Sch 120	Sch 140	Sch 160	XXS
15	1/2"	21.3	2.11	-	2.41	2.77	-	3.73	-	-	-	4.78	7.47
20	3/4"	26.7	2.11	-	2.41	2.87	-	3.91	-	-	-	5.56	7.82
25	1"	33.4	2.77	-	2.90	3.38	-	4.55	-	-	-	6.35	9.09
40	1½"	48.3	2.77	-	3.18	3.68	-	5.08	-	-	-	7.14	10.15
50	2"	60.3	2.77	-	3.18	3.91	-	5.54	-	-	-	8.74	11.07
80	3"	88.9	3.05	-	4.78	5.49	-	7.62	-	-	-	11.13	15.24
100	4"	114.3	3.05	-	4.78	6.02	-	8.56	-	11.13	-	13.49	17.12
150	6"	168.3	3.40	-	-	7.11	-	10.97	-	14.27	-	18.26	21.95
200	8"	219.1	3.76	6.35	7.04	8.18	10.31	12.70	15.09	18.26	20.62	23.01	22.23
250	10"	273.1	4.19	6.35	7.80	9.27	12.70	15.09	18.26	21.44	25.40	28.58	25.40
300	12"	323.9	4.57	6.35	8.38	10.31	14.27	17.48	21.44	25.40	28.58	33.32	25.40
350	14"	355.6	-	6.35	7.92	11.13	15.09	19.05	23.83	27.79	31.75	35.71	-
400	16"	406.4	-	6.35	7.92	12.70	16.66	21.44	26.19	30.96	36.53	40.49	-
450	18"	457.0	-	6.35	7.92	14.27	19.05	23.83	29.36	34.93	39.67	45.24	-
500	20"	508.0	-	6.35	9.53	15.09	20.62	26.19	32.54	38.10	44.45	50.01	-
600	24"	610.0	-	6.35	9.53	17.48	24.61	30.96	38.89	46.02	52.37	59.54	-

ERW Pipe Wall Thickness Selection Guide

Choosing the right wall thickness depends on your application, pressure, and applicable standard. Use the following three-step guide:

1. Typical Application and Design Reference

The standards and ranges listed above are for design reference. For final wall thickness selection, always consult the detailed specification tables on this page and confirm with your project’s design code.

Application	Reference Standard for Design	Typical Wall Thickness Range
Low-pressure water/gas lines	ASTM A53 SCH 40	2.77 mm ~ 8.18 mm
Oil/gas transmission	API 5L Gr.B	3.91 mm ~ 12.70 mm
High-pressure industrial pipelines	API 5L X42/X52	6.0 mm ~ 15.0 mm
Building, bridge, mechanical structures	ASTM A500	1.0 mm ~ 22.0 mm (OD: 21.3mm~660mm)
Building scaffolding	GB/T 3091	2.0 mm ~ 4.0 mm

2. Select by Pressure Level

Low pressure (PN≤1.6MPa): wall thickness ≥2.5mm (e.g., DN50×3.0mm)
Medium pressure (PN≤4.0MPa): wall thickness ≥5.0mm (e.g., DN150×7.11mm)
High pressure (PN≥10MPa): wall thickness ≥10mm (e.g., DN300×12.7mm)

3. Calculate Minimum Wall Thickness (for Pressure Design)

For ERW pipes that need to bear pressure, use the ASME B31.3 formula to estimate minimum wall thickness:


Where:
t: minimum wall thickness (mm)
P: design pressure (MPa)
D: outer diameter (mm)
S: allowable material stress (MPa)
E: weld coefficient (0.85 for standard ERW pipe; 1.0 for fully radiographed ERW)
Y: temperature correction factor (0.4 for carbon steel below 480°C)

Example: For a 6-inch (168.3mm OD) ERW pipe under 10MPa pressure, with S=138MPa and E=0.85, the minimum wall thickness is approximately 7.4mm.

ERW Pipe Weight Chart & Calculation Formula

Theoretical weight per meter for common ERW pipe schedules. Based on carbon steel density (7.85 g/cm³).

NPS (inch)	Outer Diameter (mm)	SCH 5		SCH 10		SCH 40 / STD		SCH 80 / XS
		WT (mm)	Wt (kg/m)	WT (mm)	Wt (kg/m)	WT (mm)	Wt (kg/m)	WT (mm)	Wt (kg/m)
1/2"	21.3	1.65	0.81	2.11	1.01	2.77	1.29	3.73	1.62
3/4"	26.7	1.65	1.03	2.11	1.30	2.87	1.71	3.91	2.20
1"	33.4	1.65	1.31	2.77	2.12	3.38	2.54	4.55	3.29
1¼"	42.2	1.65	1.93	2.77	3.15	3.68	3.48	4.85	4.47
1½"	48.3	1.65	1.93	2.77	3.15	3.68	4.05	5.08	5.41
2"	60.3	1.65	2.42	2.77	3.98	3.91	5.44	5.54	7.48
2½"	73.0	—	—	—	—	5.16	8.63	7.01	11.41
3"	88.9	2.11	4.58	3.05	6.54	5.49	11.29	7.62	15.27
3½"	101.6	2.11	5.25	3.05	7.52	5.74	13.77	—	—
4"	114.3	2.11	5.25	3.05	7.52	6.02	16.07	8.56	22.32
5"	141.3	2.77	9.50	3.40	11.74	6.55	21.77	9.53	30.97
6"	168.3	2.77	11.47	3.40	14.04	7.11	28.25	10.97	42.56
8"	219.1	2.77	14.99	3.76	20.25	8.18	42.55	12.70	64.64
10"	273.1	—	—	—	—	9.27	60.29	15.09	94.79
12"	323.9	—	—	—	—	10.31	79.62	17.48	128.07
14"	355.6	—	—	—	—	11.13	94.26	—	—
16"	406.4	—	—	—	—	12.70	122.00	—	—
18"	457.2	—	—	—	—	14.27	153.00	—	—
20"	508.0	—	—	—	—	15.09	183.00	—	—
24"	609.6	—	—	—	—	17.48	248.00	—	—

Note: "—" indicates that this specification is uncommon or not applicable in this wall thickness series.

ERW Pipe Weight Calculation Formula:

The weight calculation of ERW steel pipe is usually based on the theoretical weight formula for steel pipe. Since ERW steel pipe is a welded pipe, its calculation is the same as that of seamless steel pipe, both calculated based on the principle of unfolding a round pipe into a steel strip.

Where:
W = Theoretical weight per meter (kg/m)
T = Steel pipe wall thickness (mm)
D = Steel pipe outer diameter (mm)

0.02466 = Density coefficient of steel pipe material, applicable to ordinary carbon steel, density is taken as 7.85 g/cm³

Weight Calculation Example: For a 6-inch ERW pipe (OD=168.3mm) with wall thickness 7.11mm:
W = 0.02466 × 7.11 × (168.3 - 7.11) = 28.26 kg/m

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).

Common Applications of ERW Pipes by Size

Size Classification	Outer Diameter Range	Wall Thickness Characteristics	Main Applications
Small Diameter Pipe	21.3 - 114.3 mm (Approx. 1/2 - 4 inches)	Thinner, typically 2.0 - 6.0 mm	- Water and gas pipelines in buildings - Branch pipes for fire sprinkler systems - Furniture and scaffolding structures - Mechanical parts
Medium Diameter Pipe	114.3 - 323.9 mm (Approx. 4 - 12 inches)	Moderate, typically 4.0 - 12.7 mm	- Urban water supply and heating networks - Oil and gas gathering and transmission pipelines - Building structural support columns - General industrial fluid transportation
Large Diameter Pipe	323.9 - 610 mm (Approx. 12 - 24 inches)	Thicker, up to 19.1 mm	- Long-distance oil and gas trunk pipelines - Marine engineering and structural pile foundations - Large-scale water conservancy and industrial circulating water systems - Municipal main pipeline network

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). For a complete comparison, please refer to our [Seamless Pipe Size and Weight Chart].

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. ASTM A500 is a structural standard (non-fluid). For fluid transport, select fluid pipe standards such as ASTM A53 or API 5L

Q6: Difference between A500 ERW and A53 ERW
→ ASTM A500 is designed for structural applications (non-fluid transportation), emphasizing mechanical properties and cross-sectional shape tolerance.

ASTM A53 is a pressure/fluid standard, suitable for conveying steam, water, gas, and air in industrial pipeline systems.

Conclusion:

Selecting the right ERW pipe wall thickness is essential for balancing safety, performance, and cost. Use the charts above for quick reference, and always consult relevant design standards (ASME B36.10M, API 5L, ASTM A53) for your specific project requirements. For customized solutions or technical support, contact our engineering team.

Need Expert Advice?

Hunan Standard Steel Co., Ltd (HSCO) offers a full range of ERW carbon steel pipes in various sizes and schedules. Whether you need standard specifications or custom solutions, our team is ready to assist: info@hu-steel.com

You may be interested in the following technical documents regarding steel pipe specifications and dimensions:

● Carbon Steel ERW Pipe Grade & Specification

● Seamless Steel Pipe Dimensions and Weight Chart

● ERW pipe vs. Seamless Pipe Cost & Selection Guide