Quick answer
Specify seamless tube for high-pressure, high-temperature or critical duty such as boilers, superheaters and heat exchangers. Specify welded tube where cost matters and duty is moderate, such as structural, architectural, sanitary and general piping.
How they are made
- Seamless: a solid billet is pierced to form a hollow shell, then reduced by hot working and finished by cold drawing or cold pilgering to final size.
- Welded: strip or plate is roll-formed into a tube and welded longitudinally (commonly TIG or laser), then annealed, sized and often cold-worked.
Comparison
| Seamless | Welded | |
|---|---|---|
| Weld seam | None | One longitudinal weld |
| Typical standards | ASTM A213, A269, A312 | ASTM A249, A269, A312 |
| High pressure / temperature duty | Preferred | Used with design allowances |
| Dimensional tolerance | Very good when cold drawn or pilgered | Very good, especially when cold-sized |
| Cost | Higher | Lower |
| Typical lengths and sizes | Smaller to mid diameters; very large diameters are limited | Wide range of diameters and long lengths |
Do welded tubes corrode at the weld?
A properly made and annealed welded tube performs comparably to seamless in most corrosive environments. Low-carbon grades (304L, 316L) and correct post-weld cleaning (pickling and passivation) keep the weld zone corrosion-resistant.
What Ruby Infra Projects offers
Ruby Infra Projects lists cold-drawn and cold-pilgered stainless steel seamless tubes to ASTM A213, A249, A269 and A312 and EN/DIN/JIS standards, along with custom specifications and cut-to-length service. Request a quote.