Tesco Hastelloy C-276 Threaded Flange — Mirror-Polished, NPT Threaded Bore — Made in India
ASME B16.5 threaded (screwed) flanges with NPT & BSPT thread forms — Class 150–2500, ½″–4″ NB, DIN 2565/2566 & BS 4504 patterns, in carbon steel, stainless, duplex, Hastelloy & titanium. The no-weld flange: threaded on, not welded — for galvanised pipe, no-hot-work sites and instrument connections. ISO 9001:2015, made in Mumbai, exported to 50+ countries.
Threaded Flanges | Screwed Flanges | NPT Thread Flanges | BSPT Thread Flanges | ASME B16.5 Class 150–2500 | DIN 2565 / DIN 2566 | All Material Grades
Tesco Hastelloy C-276 Threaded Flange — Mirror-Polished, NPT Threaded Bore — Made in India
A threaded flange — also known as a screwed flange — is a pipe flange with a threaded bore that screws directly onto the male-threaded end of a pipe, creating a pressure-tight mechanical joint without any welding. The internal taper thread (NPT or BSPT) grips the pipe thread and, as the joint is tightened, the mating tapers develop a self-sealing interference fit.
Tesco Steel & Engineering manufactures Threaded Flanges per ASME B16.5 (½″–4″ NB, Class 150–2500), BS 4504, DIN 2565 (PN 6), and DIN 2566 (PN 16) in a full range of materials from Carbon Steel A105 to exotic alloys including Hastelloy C276, Inconel 625, and Titanium Gr. 2. All flanges are ISO 9001:2015 certified and supplied with EN 10204 3.1 Mill Test Certificates.
The thread standard determines compatibility with the mating pipe system. The three forms are not interchangeable — incorrect mating causes incomplete thread engagement and leakage.
| Thread Standard | Specification | Thread Angle | Taper | Primary Region | Sealing Mechanism |
|---|---|---|---|---|---|
| NPT (National Pipe Taper) | ASME B1.20.1 | 60° | 1:16 on diameter | North America | Thread interference + PTFE/compound |
| BSPT / Rc (British Standard Pipe Taper) | BS 21 / ISO 7-1 | 55° (Whitworth) | 1:16 on diameter | Europe, Asia, Middle East | Thread interference + PTFE/compound |
| BSP Parallel / Rp / G | ISO 228-1 | 55° (Whitworth) | None (parallel) | Europe (instrument fittings) | Face seal / bonded washer |
Key rule: Always specify the thread form explicitly on your purchase order (e.g., "2″ Class 300 RF Threaded Flange, ASTM A182 F316L, NPT per ASME B1.20.1"). Failure to specify defaults to the supplier's local standard, which may not match your pipe system.
| Pressure Class | Size Range (NB) | CS A105 Rating @ 38°C | CS A105 Rating @ 260°C | SS 316L Rating @ 38°C | Typical Face Types |
|---|---|---|---|---|---|
| Class 150 | ½″ – 4″ | 285 psi (19.6 bar) | 170 psi (11.7 bar) | 275 psi (19.0 bar) | RF, FF |
| Class 300 | ½″ – 4″ | 740 psi (51.1 bar) | 655 psi (45.2 bar) | 720 psi (49.6 bar) | RF, FF, RTJ |
| Class 600 | ½″ – 4″ | 1480 psi (102 bar) | 1310 psi (90.3 bar) | 1440 psi (99.3 bar) | RF, RTJ |
| Class 900 | ½″ – 4″ | 2220 psi (153 bar) | 1965 psi (135 bar) | 2160 psi (149 bar) | RF, RTJ |
| Class 1500 | ½″ – 4″ | 3705 psi (255 bar) | 3275 psi (226 bar) | 3600 psi (248 bar) | RF, RTJ |
| Class 2500 | ½″ – 3″ | 6170 psi (425 bar) | 5460 psi (376 bar) | 6000 psi (414 bar) | RTJ |
* Ratings per ASME B16.5 Table 2. Class 3000/6000/9000 threaded fittings are covered under ASME B16.11 (for couplings and half-couplings, not for flanges). Always use the actual material group rating table for the final design.
| Face Type | Abbreviation | Surface Finish | Typical Gasket | When Used |
|---|---|---|---|---|
| Raised Face | RF | 125–250 AARH serrated | Spiral wound, compressed fibre | Standard for Class 150–2500 process service |
| Flat Face | FF | 125–250 AARH serrated | Full-face rubber, PTFE | Mating with cast iron / non-metallic equipment |
| Ring Type Joint | RTJ | 3.2 μm Ra max groove | Octagonal or oval ring (R/RX/BX) | High-pressure service, Class 900 and above |
| Tongue & Groove | T&G | 125 AARH | Full-bore ring gasket | Pump and valve flanges (non-standard for B16.5) |
| Material Category | ASTM / UNS Grade | Key Properties | Typical Service |
|---|---|---|---|
| Carbon Steel | ASTM A105 | UTS 485 MPa, Yield 250 MPa | General service, water, steam, gas |
| LTCS (Low Temp.) | ASTM A350 LF2 | Impact tested to −46°C (−50°F) | Cryogenic, LNG, cold utilities |
| Alloy Steel | ASTM A182 F5, F9, F11, F22, F91 | Cr-Mo alloys, high-temp strength | Power generation, high-temp steam |
| Stainless Steel 304/304L | ASTM A182 F304 / F304L | 18Cr-8Ni, UTS 515 MPa | Mild corrosive, food, pharma |
| Stainless Steel 316/316L | ASTM A182 F316 / F316L | 16Cr-10Ni-2Mo, UTS 515 MPa | Marine, chemical, chloride service |
| Stainless Steel 321 / 347 | ASTM A182 F321 / F347 | Ti- or Nb-stabilised, sensitisation-resistant | High-temp service, boiler steam |
| 904L | ASTM A182 F904L (UNS N08904) | 20Cr-25Ni-4.5Mo-1.5Cu | H₂SO₄, phosphoric acid, seawater |
| Duplex 2205 | ASTM A182 F51 (UNS S31803/S32205) | PREN ≥ 35, UTS 620 MPa, dual phase | Offshore, subsea, desalination |
| Super Duplex 2507 / Zeron 100 | ASTM A182 F53 (S32750) / F55 (S32760) | PREN ≥ 40, UTS 795 MPa | High-chloride, deep offshore |
| Copper Nickel 90/10 | C70600 (UNS) | Biofouling resistant, seawater | Naval, offshore, heat exchangers |
| Copper Nickel 70/30 | C71500 (UNS) | Higher Ni, better high-temp corrosion | Condenser, power plants |
| Monel 400 | ASTM B564 (UNS N04400) | 67Ni-30Cu, HF acid resistant | Hydrofluoric acid, marine, brine |
| Monel K500 | UNS N05500 | Age-hardened, UTS 965 MPa | Pump shafts, high-strength marine |
| Inconel 600 | ASTM B564 (UNS N06600) | 76Ni-15Cr, oxidation resistant | Furnace, heat treatment equipment |
| Inconel 625 | ASTM B564 (UNS N06625) | 21Cr-9Mo-3.65Nb, UTS 830 MPa | Subsea, aggressive acid, aerospace |
| Incoloy 800 / 825 | UNS N08800 / N08825 | High Ni-Cr-Fe-Mo, SCC resistant | Sour gas, sulphuric/phosphoric acid |
| Hastelloy C276 | ASTM B564 (UNS N10276) | 16Cr-16Mo-4W, broadest acid resistance | Wet chlorine, HCl, H₂SO₄, FGD |
| Hastelloy C22 | ASTM B564 (UNS N06022) | 21Cr-13Mo-3W, oxidising + reducing | Mixed acid environments, pharma |
| Hastelloy C4 | ASTM B564 (UNS N06455) | 16Cr-16Mo-Ti, no PWHT needed | Thin-wall heat exchanger flanges |
| Titanium Gr. 1 / Gr. 2 | ASTM B381 F-1 / F-2 | CP titanium, excellent seawater resistance | Seawater, bleach, wet chlorine |
| Titanium Gr. 4 | ASTM B381 F-4 (UNS R50700) | Highest-strength CP-Ti, UTS 550 MPa | High-load, corrosive environments |
| Nickel 200 / 201 | UNS N02200 / N02201 | 99.6% Ni, caustic alkalis resistant | Caustic soda, food processing |
| Alloy 20 (CN-7M) | ASTM B462 (UNS N08020) | 19Cr-24Ni-3Mo-3Cu, H₂SO₄ resistant | Sulphuric acid, food & pharma |
For European piping systems and metric pressure ratings, Tesco Steel supplies threaded flanges to the following DIN standards:
| Standard | Pressure Nominal (PN) | Size Range (DN) | Thread | Face | Link |
|---|---|---|---|---|---|
| DIN 2565 | PN 6 | DN 10 – DN 80 | Rp (BSP Parallel) or Rc (BSPT) | Flat Face | DIN 2565 PN 6 Threaded Flanges |
| DIN 2566 | PN 16 | DN 10 – DN 80 | Rp (BSP Parallel) or Rc (BSPT) | Flat Face / Raised | DIN 2566 PN 16 Threaded Flanges |
| BS 4504 | PN 6 – PN 40 | DN 15 – DN 100 | BSP or BSPT | Raised Face | BS4504 Threaded Flanges |
| Feature | Threaded Flange | Socket Weld Flange |
|---|---|---|
| Connection method | Thread engagement — no welding | Pipe inserted into socket, fillet welded |
| Welding required | None (or optional seal weld) | Yes — 1 external fillet weld |
| Size range (B16.5) | ½″ – 4″ NB | ½″ – 4″ NB |
| Pressure/cyclic suitability | Non-cyclic, static pressure only | Better — weld adds fatigue life |
| Hot work permit required | No | Yes |
| Use with galvanised pipe | Yes | No (weld destroys galvanising) |
| Dismantling & reassembly | Easy — unscrew | Requires cutting weld |
| Toxic/flammable fluid service | Not recommended | Acceptable (B31.3) |
| Cost | Lower (no weld labour) | Slightly higher (welding cost) |
| Category | Standard | Scope |
|---|---|---|
| Dimensional | ASME B16.5 | Pipe flanges, Class 150–2500, ½″–24″ (threaded: ½″–4″) |
| Dimensional | DIN 2565 | Threaded flanges PN 6 |
| Dimensional | DIN 2566 | Threaded flanges PN 16 |
| Dimensional | BS 4504 | British standard flanges, metric |
| Thread Form | ASME B1.20.1 | NPT thread dimensions and tolerances |
| Thread Form | BS 21 / ISO 7-1 | BSPT (Rc) taper thread |
| Thread Form | ISO 228-1 | BSP Parallel (Rp/G) thread |
| Material – CS | ASTM A105 | Carbon steel forgings for piping |
| Material – LTCS | ASTM A350 LF2 | Low-temp carbon steel forgings |
| Material – Alloy/SS | ASTM A182 | Alloy and stainless steel forgings |
| Material – Nickel Alloys | ASTM B564 | Nickel and nickel alloy forgings |
| Material – Titanium | ASTM B381 | Titanium and titanium alloy forgings |
| Inspection | EN 10204 3.1 / 3.2 | Mill Test Certificate, third-party witness |
| Piping Code | ASME B31.3 | Process piping — defines threaded joint limitations |
| Piping Code | ASME B31.1 | Power piping — utility steam and water |
| Industry | Typical Application | Material Specified |
|---|---|---|
| Oil & Gas (non-hazardous utilities) | Instrument air, cooling water, sealing oil headers | A105, A182 F316L |
| Water & Wastewater | Pump station headers, meter connections, service connections | A105 (GI coated), A182 F316L |
| HVAC | Chilled water, hot water headers, air-handling unit connections | A105, A182 F316 |
| Power Generation | Instrument tappings, low-pressure steam utility lines | A105, A182 F11/F22 |
| Chemical Processing | Non-hazardous chemical sampling lines, gauge connections | A182 F316L, B564 C276 |
| Marine & Offshore | Seawater cooling headers, ballast utility connections | C70600 (90/10 CuNi), F316L |
| Pulp & Paper | Bleach plant utility connections, white water headers | A182 F316L, B564 C276 |
| Food & Beverage | CIP (clean-in-place) utility piping, process water | A182 F304L, F316L (ASME-BPE) |
Countries we export to: Kuwait, UAE, Germany, Saudi Arabia, West Africa, Dubai, Iraq, Congo, Mexico, Bahrain, Canada, Philippines, Thailand, Kenya, Oman, Malaysia, Turkey, Qatar, Sudan, Netherlands, Nigeria, Russia, Vietnam, Angola, Indonesia, UK, Yemen, Italy, United States, Venezuela, Kazakhstan, Algeria, Jordan, Colombia, Libya, China, Peru, Iran, South Africa, Israel, Zambia, Tanzania, Pakistan and 30+ more countries.
Domestic markets: Mumbai, Delhi, Bangalore, Hyderabad, Ahmedabad, Chennai, Kolkata, Surat, Pune, Jaipur, Lucknow, Kanpur, Nagpur, Visakhapatnam, Gujarat, Maharashtra, Rajasthan, Tamil Nadu, Telangana, Karnataka, Uttar Pradesh, West Bengal and all major Indian industrial hubs.
A complete threaded flange specification has five elements — with the thread form doing the work a weld bevel does elsewhere:
Example of a complete line item: “Threaded Flange, 1″ NB, ASME B16.5 Class 300, RF, NPT, ASTM A182 F316L, EN 10204 3.1 — 50 pcs.”
| Standard | ASME B16.5, DIN 2565/66, BS 4504 |
| Size Range | ½″ – 4″ NB (DN 15 – DN 100) |
| Pressure Class | 150, 300, 600, 900, 1500, 2500 |
| PN Rating | PN 6, PN 10, PN 16, PN 25, PN 40 |
| Thread Form | NPT, BSPT (Rc), BSP Parallel (Rp) |
| Face Types | RF, FF, RTJ |
| Cert | EN 10204 3.1 / 3.2 |