Alloy Grade Selector — Stainless Steel Pipe Fittings | Synbase Steel

Alloy Grade Selector

Match your stainless steel pipe fitting grade to your service environment using PREN threshold values. Enter your process conditions below.

Grade Recommendation Tool

Enter your process conditions to receive an initial grade recommendation based on PREN threshold values. This tool supplements — but does not replace — an engineering review for critical systems.

Service Conditions (select all that apply)

PREN Reference — Grades Available from Synbase Steel

Grade UNS PREN Max Cl⁻ (guideline) Typical Application
304LS3040318–20<50 ppmGeneral industrial, low-chloride utility
316LS3160323–25~500–1,000 ppmChemical processing, marine splash, food
317LS3170329–31~1,500 ppmHigher-chloride / slightly elevated temp vs. 316L
321S3210017–19<200 ppmHigh-temp non-chloride service (>400°C), Ti-stabilized
347S3470017–19<200 ppmHigh-temp non-chloride service, Nb-stabilized
2205 DuplexS3220535–37~3,000–10,000 ppmOffshore, desalination, moderate-chloride process
2507 Super DuplexS3275042–44>10,000 ppm (seawater)Seawater cooling, subsea, high-chloride offshore
904LN0890432–36Acid service primaryH₂SO₄ / H₃PO₄ acid, reducing acid environments

PREN = %Cr + 3.3×%Mo + 16×%N. Values are typical; confirm with mill certificate data for your specific heat.