Seamless, Welded, Welded-and-Redrawn：Choosing the Right Stainless Steel Pipe

Picking the right stainless steel pipe isn’t just a technicality—it defines pressure integrity, inner-surface quality, lifecycle cost, and install speed. Below is a clear, skimmable guide to help you match process to application and spec with confidence.

 

The Three Pipes Explained

Seamless (SMLS)

How it’s made: Pierced and hot-rolled/ cold-drawn from solid billet—no longitudinal weld.

Strength & pressure: Excellent for high pressure, shock, and cyclic loads; robust at elevated temperatures.

Sizes/standards: Broad wall availability (thin to XXS). Commonly to ASTM A312 (pipe), EN 10216-5.

Surface: Good as-drawn ID; can be honed or EP if needed on smaller sizes.

Typical uses: Oil & gas, steam, boiler lines, high-pressure chemical service.

Cost/lead time: Higher material/processing cost; longer lead times on special walls.

Welded (ERW/TIG/Laser)

How it’s made: Formed from strip and welded longitudinally, then solution-annealed (as required).

Strength & pressure: Meets code pressure ratings when produced to spec; excellent dimensional consistency.

Sizes/standards: Wide OD range, long random lengths. ASTM A312, A358 (large diameter), EN 10217-7.

Surface: Very consistent OD/ID; weld bead can be controlled/removed depending on spec.

Typical uses: General process piping, structural, water/fire protection, HVAC, low-to-medium pressure chemical lines.

Cost/lead time: Cost-effective, fast availability in common schedules.

Welded-and-Redrawn (Welded, Cold-Drawn, Annealed)

How it’s made: Welded tube that is subsequently cold-drawn (and annealed), refining grain, tolerance, and ID finish.

Strength & pressure: Combines welded availability with drawn mechanicals; excellent for thin-wall small-bore.

Sizes/standards: Common in tubing specs (ASTM A269, A213, A270 sanitary); coiled lengths available.

Surface: Superior ID/OD tolerance and finish; available EP/BPE-grade for high purity.

Typical uses: Instrumentation, sanitary/CIP/SIP, UHP gases, hydrogen/oxygen service (with proper cleaning).

Cost/lead time: Between welded and seamless; strong value where cleanliness and precision matter.

 

How to Choose: A Practical Checklist

Pressure and wall

Very high pressure, thermal shock, or fatigue: Seamless.

Code-compliant medium pressure with standard schedules: Welded.

Thin-wall, small-bore with precise tolerances: W&R.

Diameter and length strategy

Large diameter or long random lengths: Welded (or A358 for large OD).

Small-bore with long, continuous runs (fewer joints): W&R in coils.

Inner surface and cleanliness

High-purity gases, pharma, food: W&R or EP tubing per ASTM A270/BPE.

General service fluids: Welded or seamless pickled/annealed.

Corrosion and grade

Chlorides/sea/coastal: 316/316L, duplex where appropriate.

High temp or stabilized needs: 321, 347.

Aggressive media: 904L, duplex/super duplex.

Codes, tests, and documentation

Specify standards: ASTM A312/A358 (pipe), A269/A270 (tube), EN 10216-5/10217-7.

NDT: Eddy current/UT for wall integrity, RT for seam (as required).

Pressure/leak tests: Hydrostatic or helium (oxygen/hydrogen service).

Docs: EN 10204 3.1/3.2, PMI, heat-number traceability.

Fabrication and installation

Orbital-weld readiness (sanitary/UHP): W&R with tight tolerances and purge control.

Fast field install with fewer welds: Coiled W&R; press-fit systems (where approved).

 

What We Supply

Grades: 304/304L, 316/316L, 321, 347, 904L, 2205/2507 duplex, and more on request.

Dimensions:

Pipe: OD 6–610 mm with schedules from 5S to XXS (availability by grade).

Tubing: 1/8"–2" OD, tight tolerances; coiled lengths for 1/8"–1" OD.

Finishes: Pickled and annealed, mechanically polished, electropolished (EP), BPE-compliant sanitary.

QA/NDT: PMI, eddy current/UT, radiography (as specified), hydro/helium leak tests, ferrite number (welds), surface roughness reports.

Paperwork: EN 10204 3.1/3.2, full heat traceability, welding procedure qualifications upon request.

Services: Cut-to-length, beveling, orbital-weld fit-up kits, purge accessories, cleanroom packaging for oxygen/UHP.

 

Ready to Specify?

Send us your line list (medium, pressure/temperature, size/schedule, grade, standards, surface finish, tests, documentation). We’ll return a right-sized recommendation—seamless, welded, or welded-and-redrawn—plus a firm lead time and quote.