| Austenitic 304/304L Welded Pipe | 304, 304L | Cold-forming of strip or plate followed by longitudinal electric-resistance, high-frequency, or fusion welding. | Good general corrosion resistance, excellent formability, and strong weldability. The low-carbon 304L grade reduces the risk of sensitization after welding. | ASTM A312 ASTM A269 EN 10217-7 | Food and beverage lines, architectural piping, water treatment, kitchen equipment, general chemical service, and sanitary installations. | Not the preferred choice for high-chloride environments or warm seawater because chloride pitting and stress-corrosion cracking can occur. |
| Austenitic 316/316L Welded Pipe | 316, 316L | Longitudinal welded construction using formed strip or plate with controlled heat input and post-weld finishing where required. | Improved resistance to pitting and crevice corrosion compared with 304 because of its molybdenum content. | ASTM A312 ASTM A269 EN 10217-7 | Marine atmospheres, pharmaceutical equipment, chemical processing, coastal infrastructure, pulp and paper plants, and high-purity water systems. | More expensive than 304/304L. It is still not universally suitable for concentrated chlorides, hot seawater, or severe reducing acids. |
| Stabilized Austenitic Welded Pipe | 321, 347 | Longitudinal fusion-welded or electric-welded pipe produced from stabilized stainless strip or plate. | Designed for better resistance to intergranular corrosion after exposure to elevated temperatures. Grade 321 is titanium-stabilized; 347 is niobium-stabilized. | ASTM A312 ASTM A358 | High-temperature process piping, furnace components, thermal oxidizers, exhaust systems, heat-treatment equipment, and aerospace-related piping. | Use the grade and welding procedure specified for the actual service temperature, thermal cycling, and corrosion environment. |
| Large-Diameter Austenitic Welded Pipe | 304L, 316L, 321, 347 | Plate forming followed by longitudinal or circumferential fusion welding; submerged-arc welding may be used for heavy-wall or large-diameter products. | Suitable for large diameters and heavy wall thicknesses that are less practical to produce from standard tubular strip-forming processes. | ASTM A358 ASTM A312 | Process pipelines, refinery and petrochemical facilities, water transmission, cryogenic service, tank connections, and large exhaust or ducting systems. | Inspect weld quality, radiographic or ultrasonic examination requirements, dimensional tolerances, heat treatment, and surface condition. |
| Duplex 2205 Welded Pipe | UNS S31803, S32205 | Formed plate or strip welded with a procedure designed to preserve the required ferrite-austenite phase balance. | Higher strength than common austenitic grades, strong resistance to chloride stress-corrosion cracking, and good resistance to pitting. | ASTM A790 ASTM A928 EN 10217-5 | Oil and gas gathering lines, offshore platforms, desalination plants, seawater systems, chemical processing, and pressure-containing equipment. | Welding heat input, interpass temperature, shielding, and post-weld phase balance require strict control. It is not normally solution-annealed in the same way as austenitic grades. |
| Super Duplex Welded Pipe | UNS S32750, S32760 | Specialized fusion-welded construction with controlled filler metal, heat input, and corrosion-performance testing. | Very high resistance to chloride pitting, crevice corrosion, and stress-corrosion cracking, combined with high mechanical strength. | ASTM A790 ASTM A928 | Offshore production, subsea piping, seawater injection, desalination, flue-gas scrubbers, and aggressive chemical services. | Higher material and fabrication cost. Welding qualification, ferrite control, heat treatment, and corrosion testing are especially important. |
| Ferritic Stainless Welded Pipe | 409, 430, 439 | Strip-forming followed by resistance or fusion welding, commonly with controlled heat input to limit grain coarsening. | Magnetic, generally lower in nickel cost, and resistant to oxidation. Corrosion resistance varies substantially by grade. | ASTM A268 ASTM A554 | Automotive exhaust systems, appliance components, decorative tubing, heat shields, and moderately corrosive industrial applications. | Usually less ductile than austenitic grades. Welding procedure and stabilization are important because excessive heat can reduce toughness and corrosion resistance. |
| Sanitary Welded Pipe | 304L, 316L | Precision welded tube or pipe with internal bead control, grinding, polishing, and cleaning to achieve a hygienic surface. | Low-carbon stainless construction with smooth internal surfaces that reduce product retention and support clean-in-place operations. | ASTM A270 3-A Sanitary Standards ASME BPE | Dairy processing, breweries, food production, pharmaceutical manufacturing, biotechnology, and high-purity water distribution. | Specify surface roughness, orbital-welding requirements, passivation, electropolishing, cleanliness, drainability, and hygienic fitting compatibility. |
| Heat-Exchanger and Boiler Welded Tube | 304L, 316L, 321, 347 | Precision longitudinal welding followed by sizing, testing, and finishing appropriate for heat-transfer service. | Good dimensional consistency and corrosion resistance with thin-wall options for efficient heat transfer. | ASTM A249 ASTM A269 EN 10312 | Shell-and-tube heat exchangers, condensers, boilers, evaporators, superheaters, and process heating equipment. | Review pressure, temperature, vibration, thermal cycling, tube-to-tubesheet joining, eddy-current testing, and resistance to the process fluid. |
| Decorative and Structural Welded Tube | 304, 304L, 316, 316L, 430 | Cold-formed strip welded longitudinally, then mechanically polished, brushed, or supplied with a mill finish. | Good appearance, cleanability, and moderate structural performance; surface finish is often a primary specification. | ASTM A554 EN 10219 | Railings, handrails, furniture, architectural structures, display equipment, vehicle components, and public-space installations. | Confirm whether the product is intended for pressure service or only mechanical and decorative use. ASTM A554 products are generally not pressure-rated pipe. |