UNS N08904 904L Thick Wall Seamless Stainless Steel Pipe SCH 80S 160S ASTM A312 High Pressure Chemical OD 33.4-219.1mm

When process conditions combine aggressive chemical attack with elevated operating pressures, standard wall pipe specifications are insufficient. Our UNS N08904 904L thick wall seamless pipes in SCH 80S and SCH 160S deliver the structural integrity required for high pressure chemical injection lines, urea synthesis reactors, and offshore processing topsides where both mechanical and corrosion resistance demands are extreme. Manufactured to ASTM A312 with full NACE MR0175/ISO 15156 compliance for sour service environments.

* Calculated per ASME B31.3 at 20°C with seamless pipe quality factor E=1.0 and design factor 0.72 of yield. Actual rating subject to project-specific design code and temperature derating.

Thick wall 904L seamless pipes require specialized manufacturing. Our process begins with vacuum induction melting (VIM) followed by electroslag remelting (ESR) to produce ultra-clean ingots with minimized inclusion content and segregation. The ingots are hot extruded into hollow shells at 1150-1200°C under controlled strain rates to ensure complete recrystallization. Cold pilgering (cold reducing) achieves the final wall thickness with dimensional tolerances of ±10% on WT, followed by solution annealing and rapid quenching. This route eliminates the centerline porosity risks associated with conventional piercing processes, delivering 100% dense, homogeneous pipe walls suitable for the most demanding high pressure applications.

All thick wall 904L pipes supplied for sour service are tested in accordance with NACE MR0175/ISO 15156-3 for resistance to sulfide stress cracking (SSC) and stress corrosion cracking (SCC). Hardness is verified at ≤ 90 HRB (22 HRC maximum) on every heat treatment lot. PMI and full traceability from melt to finished product are maintained through our EN 10204 3.1 certified material test certificate system.