Every standard that governs buttweld pipe fittings — dimensional, material, and inspection. What each covers and when to specify it.
Every buttweld fitting is governed by two standards — one for dimensions, one for material. Both must be specified correctly when ordering.
Define the physical dimensions — outside diameter, centre-to-face, wall thickness, bevel angle. Ensure that fittings from any manufacturer fit the same pipe. ASME B16.9 is the primary dimensional standard used worldwide.
Define the chemical composition, mechanical properties, heat treatment, and testing requirements for the fitting material. Each grade has a specific material standard — e.g. SS 316L fittings are made to ASTM A403 WP316L.
The universal dimensional standard for buttweld fittings in all materials and all schedules from Sch 10 to XXS. Covers elbows, tees, reducers, caps, stub ends, and returns in sizes ½" NB to 48" NB. Required by ASME B31.3 (Process Piping) and virtually all industrial piping codes worldwide.
Covers only stainless steel buttweld fittings in Sch 5S and 10S (light wall). Lower pressure rating than ASME B16.9 equivalents. Used in food & beverage, dairy, pharmaceutical, and clean utility piping where heavy wall is not required and weight/cost savings matter.
European equivalent to ASME B16.9 for stainless steel and nickel alloy buttweld fittings. Required for projects in Europe, and increasingly specified for European EPC projects worldwide. Dimensional values are slightly different from ASME B16.9 — always confirm which standard applies before ordering.
| Grade / Material | ASTM Material Standard | Dimensional Standard | Typical Application |
|---|---|---|---|
| SS 304 / 304L | ASTM A403 WP304 / WP304L | ASME B16.9 | General corrosion service, food, pharma |
| SS 316 / 316L | ASTM A403 WP316 / WP316L | ASME B16.9 | Marine, offshore, pharmaceutical, chloride |
| SS 321 | ASTM A403 WP321 | ASME B16.9 | High temperature 425–900°C |
| SS 347 / 347H | ASTM A403 WP347 / WP347H | ASME B16.9 | Refinery, petrochemical high temp |
| SS 310S | ASTM A403 WP310S | ASME B16.9 | Furnaces, kilns, extreme high temp |
| SS 904L | ASTM B366 / UNS N08904 | ASME B16.9 | Sulfuric acid, reducing acid service |
| WPB Carbon Steel | ASTM A234 WPB | ASME B16.9 | General service -29°C to 427°C |
| WPC Carbon Steel | ASTM A234 WPC | ASME B16.9 | General service, higher strength |
| LTCS WPL6 | ASTM A420 WPL6 | ASME B16.9 | Low temperature to -46°C |
| LTCS WPL3 | ASTM A420 WPL3 | ASME B16.9 | Low temperature to -73°C, LNG |
| WP11 Alloy Steel | ASTM A234 WP11 Cl.1 / Cl.3 | ASME B16.9 | High temp 450–550°C, boilers |
| WP22 Alloy Steel | ASTM A234 WP22 Cl.1 / Cl.3 | ASME B16.9 | High temp 550–600°C, refineries |
| WP91 Alloy Steel | ASTM A234 WP91 | ASME B16.9 | Ultra-supercritical power 600–649°C |
| WP9 Alloy Steel | ASTM A234 WP9 | ASME B16.9 | Hydrogen reformers, sulfur plants |
| WP5 Alloy Steel | ASTM A234 WP5 | ASME B16.9 | Refinery furnaces, FCCU |
| Duplex S31803 | ASTM A815 WP-S31803 | ASME B16.9 | Offshore, seawater, chemical |
| Super Duplex S32750 | ASTM A815 WP-S32750 | ASME B16.9 | Deepwater offshore, NORSOK |
| Super Duplex S32760 | ASTM A815 WP-S32760 | ASME B16.9 | North Sea, mixed acid service |
| Inconel 625 | ASTM B366 WPH-625 (N06625) | ASME B16.9 | Offshore risers, subsea, FGD |
| Hastelloy C276 | ASTM B366 WPH-C276 (N10276) | ASME B16.9 | Aggressive chemical, chlorine |
| Incoloy 825 | ASTM B366 WPH-825 (N08825) | ASME B16.9 | Sour gas, sulfuric acid |
| Monel 400 | ASTM B366 WPHM-400 (N04400) | ASME B16.9 | HF alkylation, seawater |
| CuNi 90/10 | ASTM B466 / B467 (C70600) | ASME B16.9 | Seawater cooling, marine |
| CuNi 70/30 | ASTM B466 / B467 (C71500) | ASME B16.9 | Desalination, naval, high velocity |
The standard MTC for industrial pipe fittings. Issued by the manufacturer's own Quality Control department. Contains chemical composition, mechanical test results, heat number, and confirmation of compliance with the material specification. Provided as standard with all Shree Impex Steel supply.
Same as 3.1 but additionally witnessed and countersigned by an independent third-party inspection body (SGS, Bureau Veritas, TÜV, Intertek) or the purchaser's representative. Required for nuclear, critical offshore, and some European projects. Available on request — advise at inquiry stage.
A declaration of compliance by the manufacturer based on non-specific inspection. Used for non-critical standard grades in general industrial service. Less commonly specified than 3.1 for buttweld fittings.
Tell us the standard, grade, size, and schedule. We will confirm compliance and provide a quote within 4 hours.