What is the difference between seamless and ERW pipe?

ERW Pipe Demand Spans Far Beyond “Just Construction” — Here’s Where It’s Used Most

Electric Resistance Welded (ERW) pipe is one of the most widely purchased steel pipe forms because it balances availability, dimensional consistency, and cost. It’s made from steel coil/strip formed into a tube and welded along the length (typically high-frequency welding), then tested and finished to meet specific service requirements.

For buyers, the key takeaway is simple: ERW shows up wherever the design pressure/temperature is moderate, installation speed matters, and the applicable standard explicitly recognizes welded pipe.

Industries that commonly use ERW pipe

1) Oil & gas pipeline transportation (onshore, gathering, distribution, many transmission cases)

Typical uses

• Crude and product lines (selected ranges)

• Natural gas gathering and distribution lines

• Production water and utility lines inside facilities

Why ERW is chosen

• Strong enough for many pipeline duties when ordered to the correct specification level and testing package.

• Efficient manufacturing supports large-volume projects.

Common specifications to reference

• ISO 3183 covers seamless and welded steel pipe for petroleum and natural gas pipeline transportation systems. 

• ASME B31.8 governs gas transmission/distribution systems (the piping system code that drives design/installation compliance). 

2) Municipal water transmission & distribution (large-diameter steel water pipe systems)

Typical uses

• Raw water intake lines, transmission mains

• Plant interconnects, pump station piping, river crossings (depending on design)

Why ERW/welded steel is chosen

• Welded steel pipe systems are well established for water networks, especially at larger diameters where logistics and installation practices favor welded joints and robust coatings/linings.

Common specifications to reference

• AWWA C200 describes electrically butt-joint-welded straight-seam or spiral-seam pipe (and seamless) for water transmission/distribution and water system facilities. 

3) Fire protection systems (sprinkler mains, fire service connections, valve trim applications)

Typical uses

• Fire sprinkler piping (wet/dry/preaction/deluge system piping per project design)

• Fire department connections and private fire service mains (by jurisdiction and design)

Why ERW is chosen

• Standards explicitly recognize welded steel pipe for fire protection, and procurement often prioritizes consistent dimensions for grooving/threading plus dependable testing.

Common specifications to reference

• ASTM A795 covers black or galvanized welded and seamless steel pipe for fire protection use. 

• NFPA documentation (proposal/committee material) also lists steel piping standards used in sprinkler-related applications (including A795/A53/A135 in the referenced table). 

4) Buildings, bridges, and general structural fabrication (structural tubing and hollow sections)

Typical uses

• Building frames, bracing, columns, secondary steel

• Bridges and general structural members (where tubular sections are designed in)

Why ERW is chosen

• Excellent dimensional control and repeatability for fabrication, welding, and fit-up.

Common specifications to reference

• ASTM A500 covers cold-formed welded and seamless carbon steel structural tubing for bridges/buildings and general structural purposes.

5) General mechanical & pressure service (plant utilities and “everyday” piping)

Typical uses

• Steam/water/gas/air service in ordinary conditions

• Mechanical piping where the governing standard permits ERW and the duty is not extreme

Why ERW is chosen

• Widely accepted for “ordinary use” pressure lines when specified correctly.

Common specifications to reference

• ASTM A53: pipe intended for mechanical and pressure applications; acceptable for ordinary uses in steam, water, gas, and air lines (includes ERW Type E). 

• ASTM A135: ERW steel pipe intended for conveying gas, vapor, water, or other liquid

6) Industrial systems beyond the “big three” (infrastructure-heavy sectors)

You’ll also see ERW pipe routinely purchased in:

• Manufacturing plants (compressed air, utility piping, guards/frames)

• Transportation facilities (structural members, protective barriers)

• Agriculture and irrigation (water conveyance, mechanical structures)

• Energy & utilities (ancillary piping, supports, non-critical service lines)

These uses are usually driven by the same logic: standard acceptance + suitable duty + economic advantage.

Conclusion

If you’re buying ERW pipe, you’re in the mainstream of the market: energy pipelines, municipal water, fire protection, structural fabrication, and general mechanical piping all rely on ERW—as long as the pipe is ordered to the right standard, with the right testing and finishing requirements. The smartest procurement teams don’t argue “ERW vs seamless” in the abstract; they align service conditions + governing code/standard + QA package and then buy accordingly.