Reference
Standards and grades
Every component is specified by three things: the standard that fixes its dimensions, the standard its material is made to, and the grade.
Illustration
Forged fittings →ASME B16.11
- MSS SP-97
- Olets
- MSS SP-83
- Unions
- MSS SP-95
- Swage nipples
- MSS SP-79
- Reducer inserts
Flanges →ASME B16.5
- ASME B16.47
- Series A & B
- ASME B16.36
- Orifice flanges
- ASME B16.48
- Spectacle and paddle blinds
- EN 1092-1 · BS 10
- European and British flanges

About each standard
Summaries only. The published standard governs in all cases.
IS 1239 Part 2 : 2004Indian Standard – Steel Tubes, Tubulars and Other Wrought Steel Fittings – Part 2: Steel Pipe Fittings
Butt weld fittings in mild steel for general plumbing, HVAC, fire protection, and low-pressure industrial use. Covers the B (Medium) and C (Heavy) wall classes of this range; the steel is IS 2062 Gr. A.
- Class B (Medium): Working pressure ~42 bar cold water
- Class C (Heavy): Working pressure ~63 bar cold water
- Sizes: ½" NB to 6" NB standard range
- Radius: 1.25D (mild steel range)
- End connection: Butt weld, bevelled ends
- Hydrostatic test at 1.5× design pressure before supply
ASME B16.9Factory-Made Wrought Buttwelding Fittings
Covers the full range of industrial butt weld fittings (elbows, tees, reducers, caps, returns) in carbon steel, alloy steel, and stainless steel from ½" to 48" NB.
- Applies to NPS ½" through 48" (DN 15 through DN 1200)
- Schedule wall: STD / XS / XXS plus full SCH range
- Radius: Long Radius (LR) 1.5D and Short Radius (SR) 1.0D elbows
- Dimensional tables are the only source of 'legal' wall thickness
- No pressure-temperature rating: use ASME B31.3 / B31.1 with pipe schedule
- End prep: per ASME B16.25 bevel
BS-10British Standard – Flanges and Bolting for Pipes, Valves and Fittings
The dominant flange standard in India for water, HVAC, and general utility service. Widely used on government tenders and municipal infrastructure projects.
- Table D: ~10 bar (the most common table in India)
- Table E: ~16 bar (medium pressure)
- Table F: ~25 bar (higher pressure)
- Flat face (FF) with full-face gasket is the default
- Bolt pattern and PCD differ from ASME B16.5: not interchangeable
- Material: IS 2062 Gr. A / mild steel standard
ASME B16.5Pipe Flanges and Flanged Fittings: NPS ½ Through NPS 24
The global standard for pressure-rated flanges. Defines seven pressure classes (150 through 2500) with pressure-temperature ratings for multiple material groups.
- Pressure classes: 150 / 300 / 400 / 600 / 900 / 1500 / 2500
- P-T ratings vary by material group and temperature
- Carbon steel A105 (Group 1.1) @ 38°C: Class 150 ~20 bar, Class 300 ~51 bar; stainless and alloy groups rate differently
- Raised Face (RF) is the standard facing type
- Ring Type Joint (RTJ) for high-pressure critical service
- Bolt torque and gasket requirements are user's responsibility
ASME B16.11Forged Fittings, Socket-Welding and Threaded
Covers socket weld and threaded forged fittings in Class 2000#, 3000#, 6000#, and 9000# for small bore high-pressure service.
- Classes: 2000# (threaded only), 3000#, 6000#, 9000#
- Socket weld: ½" to 4" NB; Threaded: ¼" to 4" NB
- Material: ASTM A105N (carbon steel), A182 F304/316 (stainless)
- Gap of 1.5 mm required between pipe and socket bottom before welding
- Single fillet weld at socket face: no back-welding possible
- No pressure-temperature rating: determined by pipe schedule
MSS SP-97Integrally Reinforced Forged Branch Outlet Fittings – Socket Welding, Threaded, and Buttwelding Ends
Covers Weldolet, Sockolet, Threadolet, Elbolet, Nipolet, and Latrolet branch connection fittings. Self-reinforcing; no separate reinforcement pad needed within rating tables.
- Weldolet: butt weld branch (no fillet); highest integrity
- Sockolet: socket weld branch
- Threadolet: threaded branch
- Elbolet: branch on elbow (for pig traps and instrumentation)
- Nipolet: integrated nipple for vent/drain without extra coupling
- Run-to-branch ratio determines reinforcement adequacy
ISO 2853 / 3-A SSITri-Clamp Sanitary Fittings – ISO 2853 and 3-A Sanitary Standards
Tri-Clamp (TC) is the global standard for quick-release hygienic connections in food, beverage, dairy, and pharmaceutical applications.
- Two ferrules + one clamp + one gasket = complete joint
- Gasket materials: silicone (food), EPDM (steam), PTFE (aggressive chemicals)
- Standard sizes: ½" TC to 6" TC (OD-based sizing, not NB)
- Internal Ra ≤ 0.8 µm standard; ≤0.4 µm for pharma (electropolished)
- CIP: Clean-In-Place at 85–95°C; SIP: Steam-In-Place at 121–135°C
- Clamp styles: single-pin (manual), double-pin (vibration), sanitary wing nut
DIN 11851Hygienic Pipe Fittings – Milk Pipe Unions (DIN 11851)
Traditional European dairy fitting standard. Slot nut and liner seal design. Common in German, Austrian, and continental European dairy equipment.
- Thread: DIN coarse thread with liner groove
- Max pressure: 6 bar; Max temp: 130°C
- Sizes: DN25 to DN150
- Material: 1.4301 (304) or 1.4404 (316L)
- Gasket: EPDM or silicone
- Not directly interchangeable with SMS or IDF
SMS 1145Dairy Pipe Couplings: Swedish Standard (SMS 1145)
Swedish standard for threaded hygienic pipe couplings (unions) on stainless steel tube, widely used in Scandinavian dairy, brewing and food plants.
- Union of a male part, a nut and a seal ring: opened without cutting the line
- Sized by tube outside diameter; confirm the tube series and wall with the order
- Not directly interchangeable with DIN 11851 or IDF unions
Buttweld fittings
- ASTM A234
- Carbon and alloy steel fittings for moderate and high temperature
- ASTM A420
- Carbon and alloy steel fittings for low-temperature service
- ASTM A403
- Austenitic stainless steel fittings
- ASTM A815
- Duplex and super duplex stainless steel fittings
Forged fittings and flanges
- ASTM A105
- Carbon steel forgings for ambient and higher temperature
- ASTM A350
- Carbon and low-alloy steel forgings for low-temperature service
- ASTM A182
- Alloy, stainless and duplex steel forgings
PipeReference
- ASTM A106
- Seamless carbon steel pipe for high temperature
- ASTM A53 / API 5L
- Welded and seamless carbon steel pipe, line pipe
- ASTM A333
- Carbon and alloy steel pipe for low temperature
- ASTM A335
- Seamless ferritic alloy steel pipe for high temperature
- ASTM A312 / A358
- Seamless, welded and EFW austenitic stainless steel pipe
- ASTM A790
- Duplex stainless steel pipe
PlateReference
- ASTM A285 / A515 / A516
- Carbon steel pressure vessel plate
- ASTM A387
- Chromium-molybdenum alloy steel plate
- ASTM A203
- Nickel alloy steel plate for low temperature
- ASTM A240
- Stainless and duplex steel plate, sheet and strip
Stud bolts and nutsReference
- ASTM A193
- Alloy and stainless steel bolting for high temperature
- ASTM A320
- Alloy steel bolting for low temperature
- ASTM A194
- Nuts for high-pressure and high-temperature bolting
| Pipe | Plate | Buttweld fitting | Forging / flange |
|---|---|---|---|
| A106 Gr. A | A285 Gr. C | A234 WPA | A105 (in our catalogue) |
| A106 Gr. B / A53 Gr. B / API 5L Gr. B | A515 / A516 Gr. 60 | A234 WPB | A105 (in our catalogue) |
| A106 Gr. C | A515 / A516 Gr. 70 | A234 WPC | A105 (in our catalogue) |
| Pipe | Plate | Buttweld fitting | Forging / flange |
|---|---|---|---|
| IS 1239 Part 1, Medium | IS 2062 Gr. A | IS 2062 Gr. A, B class (in our catalogue) | IS 2062 Gr. A (in our catalogue) |
| IS 1239 Part 1, Heavy | IS 2062 Gr. A | IS 2062 Gr. A, C class (in our catalogue) | IS 2062 Gr. A (in our catalogue) |
| Pipe | Plate | Buttweld fitting | Forging / flange |
|---|---|---|---|
| A333 Gr. 6 | A516 Gr. 60 | A420 WPL6 (in our catalogue) | A350 LF2 |
| A333 Gr. 3 | A203 Gr. E | A420 WPL3 | A350 LF3 |
| Pipe | Plate | Buttweld fitting | Forging / flange |
|---|---|---|---|
| A335 P1 | A204 Gr. B | A234 WP1 | A182 F1 |
| A335 P11 | A387 Gr. 11 | A234 WP11 (in our catalogue) | A182 F11 (in our catalogue) |
| A335 P12 | A387 Gr. 12 | A234 WP12 | A182 F12 |
| A335 P22 | A387 Gr. 22 | A234 WP22 (in our catalogue) | A182 F22 (in our catalogue) |
| A335 P5 | A387 Gr. 5 | A234 WP5 | A182 F5 |
| A335 P9 | A387 Gr. 9 | A234 WP9 | A182 F9 |
| A335 P91 | A387 Gr. 91 | A234 WP91 (in our catalogue) | A182 F91 (in our catalogue) |
| Pipe | Plate | Buttweld fitting | Forging / flange |
|---|---|---|---|
| A312 TP304 / A358-304 | A240 304 | A403 WP304 (in our catalogue) | A182 F304 (in our catalogue) |
| A312 TP304L / A358-304L | A240 304L | A403 WP304L (in our catalogue) | A182 F304L (in our catalogue) |
| A312 TP316 / A358-316 | A240 316 | A403 WP316 (in our catalogue) | A182 F316 (in our catalogue) |
| A312 TP316L / A358-316L | A240 316L | A403 WP316L (in our catalogue) | A182 F316L (in our catalogue) |
| A312 TP317 | A240 317 | A403 WP317 | A182 F317 |
| A312 TP321 / A358-321 | A240 321 | A403 WP321 | A182 F321 |
| A312 TP347 / A358-347 | A240 347 | A403 WP347 | A182 F347 |
| Pipe | Plate | Buttweld fitting | Forging / flange |
|---|---|---|---|
| A790 UNS S31803 | A240 UNS S31803 | A815 UNS S31803 | A182 F51 |
| A790 UNS S32750 | A240 UNS S32750 | A815 UNS S32750 | A182 F53 |
Fitting and forging grades tabulated in our Technical Catalog. The rest of the chart is an industry reference for the grades normally specified together, not a list of what we stock; other grades are quoted on enquiry. Grades are ASTM, except mild steel, which is to Indian Standards. The project specification governs.
Enquiries
Specifying to one of these standards?
Send the specification and we will confirm what we supply against it, in which grades and sizes, and with what documentation.
