ASTM A312 TP317L / UNS S31703 / 1.4438 Stainless Steel Seamless Pipe For Power Generation
ASTM A312 TP317L seamless pipe is a seamless austenitic stainless steel pipe manufactured to ASTM A312/A312M specification. The grade TP317L corresponds to UNS S31703, a low-carbon, molybdenum-bearing austenitic stainless steel. This seamless pipe has no welded seam and is typically produced by hot piercing/extrusion followed by cold drawing, cold rolling, or hot finishing as required. TP317L seamless stainless steel pipe is used in chemical processing, pulp and paper, flue-gas desulfurization, heat exchangers, condensers, petrochemical/power piping, food/pharmaceutical process lines, and other systems requiring better chloride pitting/crevice corrosion resistance than 316L and good elevated-temperature strength.
Differentiation advantages vs. 316L:
Higher molybdenum (3.0–4.0%) and generally higher chromium/nickel than 316L.
Higher PREN (Pitting Resistance Equivalent Number, approximately Cr + 3.3Mo + 16N): typically about 30–34 for 317L vs. roughly 24–28 for 316L.
Better resistance to chloride pitting/crevice corrosion and to several aggressive acids.
Better elevated-temperature strength/creep resistance than 316L.
Low carbon improves weldability and resistance to sensitization.
Seamless construction eliminates weld-seam integrity concerns in critical pressure/corrosive service.
Chemical Composition:
| C |
≤ 0.030 |
| Mn |
≤ 2.00 |
| P |
≤ 0.045 |
| S |
≤ 0.030 |
| Si |
≤ 1.00 |
| Cr |
18.00 – 20.00 |
| Ni |
11.00 – 15.00 |
| Mo |
3.00 – 4.00 |
| N |
≤ 0.10 |
| Fe |
Balance |
Mechanical Properties:
| Tensile Strength, Rm |
≥ 485 MPa (70 ksi) |
| Yield Strength, Rp0.2 |
≥ 170 MPa (25 ksi) |
| Elongation (50 mm gauge) |
≥ 35% |
| Hardness, HB |
≤ 217 HB |
| Hardness, HRB |
≤ 95 HRB |
Main Features:
Excellent ductility, weldability, and formability
Good high-temperature strength and oxidation resistance
Superior pitting and crevice corrosion resistance in chloride media
Typical Applications:
Chemical processing
Pulp & paper plants
Petrochemical and refinery sour service
Wastewater treatment
Flue gas desulfurization (FGD) systems
High-temperature process piping
Condenser and heat-exchanger tubes/pipes
Power generation plants
Food, beverage, and pharmaceutical process lines
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