Threaded Flange Manufacturer in India | TH / THRF / THFF / Screwed Flange / NPT / BSP | ASME B16.5 | Remax Forge
Key Features
Zero welding — screws directly onto pipe thread
The ONLY standard flange type that requires no welding. Tapered internal thread (NPT or BSP) screws onto the pipe external thread.
ATEX zone safe — approved for no-hot-work areas
When welding is strictly prohibited in explosive/flammable atmospheres, Threaded Flange is the only compliant solution.
Available in NPT (US) and BSP (International) thread
Specify NPT (ASME B1.20.1) for US/American standard, or BSP/BSPT (ISO 7/1) for UK and international projects. Not interchangeable.
When Threaded Flanges Are the ONLY Safe Choice
What is a Threaded Flange?
A Threaded Flange (also called Screwed Flange) has a tapered internal thread that screws directly onto the external thread of the pipe — NO WELDING REQUIRED. This makes it the ONLY standard flange type that can be installed in environments where welding is strictly prohibited.
Industry Abbreviations & Thread Standards
⚠️ NPT and BSP threads are NOT interchangeable — they will not seal properly together. Always specify which thread form when ordering.
Technical Limitations Buyers Must Know:
- NOT suitable for cyclic or vibration service (threads can loosen and leak)
- NOT recommended above Class 600# (leakage risk at higher pressure)
- Temperature range is more limited than welded flanges
- Requires thread sealant (PTFE tape or thread compound) to achieve a leak-tight joint
🔗 For high-pressure applications requiring welded connections, see our Weld Neck Flange. For small-bore high-pressure welded connections, see Socket Weld Flange.
Standard Specifications
Complete specifications for Threaded / Screwed Flanges — buyer-ready in one table:
| Property | Detail |
|---|---|
| Product Names | Threaded Flange, Screwed Flange, THRF, THFF, NPT Flange, BSP Flange |
| Size Range | ½" (15 NB) to 4" (100 NB) — standard threaded range; up to 6" on request |
| Pressure Classes | 150#, 300#, 600#, 900# (ASME B16.5); higher classes not recommended for threaded joints |
| Thread Types | NPT (ASME B1.20.1) — taper thread, US standard; BSP/BSPT (ISO 7/1) — British/international |
| Face Types | THRF (Raised Face), THFF (Flat Face) |
| Standards | ASME B16.5, ASME B1.20.1 (NPT), ISO 7/1 (BSP), BSEN 10226, BS 21 |
| Thread Sealant | PTFE tape, Loctite 565, Rector Seal or equivalent thread compound required |
| No Hot Work | Zero welding required — suitable for ATEX / Ex hazardous zones |
| MTC | EN 10204 3.1 standard; 3.2 on request |
| Lead Time | 7–14 days standard |
Threaded Flange Material Grades
We manufacture Threaded Flanges in all standard materials — Carbon Steel, Stainless Steel, Duplex, Super Duplex, Alloy Steel, and Nickel Alloys:
| Material Category | Grades / Specifications |
|---|---|
| Stainless Steel Threaded Flanges | ASTM/ASME A/SA182: F304, F304L, F316, F316L, F316H, F316Ti, F321, F347; Cast: CF3, CF3M, CF8, CF8M; DIN: 1.4301, 1.4306, 1.4401, 1.4404, 1.4408, 1.4409 |
| Duplex Steel Threaded Flanges | UNS S31803/S32205 — ASTM A182 Gr F51, F52, F53, F54, F55, F57, F59, F60, F61 |
| Super Duplex Threaded Flanges | UNS S32750/S32760 — ASTM A182 Gr F53, F55; Zeron 100 |
| Carbon Steel Threaded Flanges | ASTM/ASME A/SA105, A105N, A216-WCB; A350 LF2 (low temp); A694 F52/F56/F60/F65/F70/F80 (high yield); DIN 1.0460, 1.0402, 1.0619 |
| Alloy Steel Threaded Flanges | ASTM A182/ASME SA182: F5, F9, F11, F12, F22, F91 (all P-grades for high temp service) |
| Nickel Alloy Threaded Flanges | Inconel 600, 601, 625, 718, 690, X750 (ASTM B564/ASME SB564); Incoloy 800, 800H, 800HT, 825, 925 |
| Hastelloy Threaded Flanges | C276 (UNS N10276), C22 (UNS N06022), C4, C2000, B2, B3, X (ASTM B564) |
| Monel Threaded Flanges | Monel 400 (UNS N04400), Monel K500 (UNS N05500) — ASTM B564 |
| Pure Nickel Threaded Flanges | Nickel 200, 201, 205, 205LC — ASTM B564/ASME SB564 |
| Copper Nickel Threaded Flanges | CuNi 90/10 (C70600), CuNi 70/30 (C71500), UNS C71640 — ASTM/ASME SB 61/62/151/152 |
| Titanium Threaded Flanges | Gr.1, Gr.2, Gr.4, Gr.5, Gr.7 — ASTM B381/ASME SB381; R50250/R50400/R50550/R50700/R52400/R53400/R56400 |
| Aluminium Threaded Flanges | 5052, 6061, 6063, 2017, 7075 |
| Brass Threaded Flanges | 3602, 2604, H59, H62 |
| Special Alloy Threaded Flanges | Alloy 20 (ASTM B462 SB462 — Carpenter 20Cb-3); SMO 254/6Mo (UNS S31254, DIN 1.4547); Al6XN; AISI 4130; AISI 4140; Nimonic 75/80A/90; Gunmetal; Cast Iron |
Forged Raw Billets stockThreaded Flange Standards & Specifications
Manufactured per ASME B16.5, ASME B1.20.1 (NPT), ISO 7/1 (BSP), BSEN 10226, BS 21, and DIN standards:
| Standard / Spec | Scope / Application Details |
|---|---|
| 🇺🇸ANSI/ASME B16.5 | NPS ½" to 24" — the primary standard for most flanges |
| 🇺🇸ASME B16.47 Series A (MSS SP-44) | NPS 26" to 60" — large diameter |
| 🇺🇸ASME B16.47 Series B (API 605) | NPS 26" to 60" — large diameter (lighter) |
| 🇺🇸ASME B16.36 | Orifice flanges |
| 🇺🇸ASME B16.48 | Line blinds & spectacle blinds |
| 🇪🇺DIN 2501 / EN 1092-1 | European metric standard — PN ratings |
| 🇯🇵JIS B2220 | Japanese Industrial Standard |
| 🇬🇧BS 4504 / BS 10 Table D/E/F/H | British Standard |
| 🇺🇸MSS SP-44 | Large diameter steel pipeline flanges |
| 🇺🇸API 6A | Wellhead and Christmas tree equipment |
| 🇺🇸API 605 | Large diameter carbon steel flanges |
| 🇺🇸AWWA C207 | Water works flanges |
| 🇷🇺GOST 12820 / 12821 | Russian/CIS standard |
| 🇦🇺AS 2129 / AS 4087 / AS/NZS 4331.1 | Australian standard |
| 🇰🇷KS B1503 | Korean standard |
| 🌐ISO 7005-1 / ISO 9624 | International standard |
| 🇺🇸SAE J518 | Hydraulic flanged tube fittings |
| 🇨🇳GB Standard | Chinese national standard |
ASME B16.5 Threaded Flange Dimensions Table
Class 150# NPT threaded flanges per ASME B16.5. Weights approximate for Carbon Steel A105:
Please specify NPT or BSP thread when ordering. Default is NPT unless specified.
NPS (inch)↕ | Thread (NPT)↕ | Flange OD (mm)↕ | Bolt Circle (mm)↕ | No. Bolts↕ | Bolt Ø (mm)↕ | Flange Thickness T (mm)↕ | Bore at thread end (mm)↕ | Approx Wt CS (kg)↕ |
|---|---|---|---|---|---|---|---|---|
| ½ | ½ NPT | 89 | 60 | 4 | 16 | 11.2 | 21.3 | 0.4 |
| ¾ | ¾ NPT | 98 | 70 | 4 | 16 | 12.7 | 26.7 | 0.5 |
| 1 | 1 NPT | 108 | 79 | 4 | 16 | 14.3 | 33.4 | 0.7 |
| 1¼ | 1¼ NPT | 117 | 89 | 4 | 16 | 15.9 | 42.2 | 0.9 |
| 1½ | 1½ NPT | 127 | 98 | 4 | 16 | 17.5 | 48.3 | 1.1 |
| 2 | 2 NPT | 152 | 121 | 4 | 19 | 19.1 | 60.3 | 1.5 |
| 2½ | 2½ NPT | 178 | 140 | 4 | 19 | 22.4 | 73.0 | 2.2 |
| 3 | 3 NPT | 190 | 152 | 4 | 19 | 23.9 | 88.9 | 2.8 |
| 4 | 4 NPT | 229 | 190 | 8 | 19 | 23.9 | 114.3 | 4.2 |
* Please specify NPT or BSP thread when ordering. Default is NPT unless specified. Dimensions per ASME B16.5. Weights are approximate for Carbon Steel A105.
Flange Face Types
Threaded Flanges are available as THRF (Raised Face — most common) and THFF (Flat Face for cast iron or low-pressure mating flanges).
Raised Face (RF)
Most common. A raised circular ring that concentrates pressure on a smaller area to compress the gasket. Height: 1/16" for Class 150/300; 1/4" for Class 400 and above.
Flat Face (FF)
No raised portion; entire flange face is in the same plane. Used when mating against cast iron or non-metallic flanges to avoid cracking on bolt tightening.
Ring Type Joint (RTJ)
Oval or octagonal groove machined into the face; a metal ring gasket seats in the groove. Used in high-pressure, high-temperature critical service (refineries, oil fields).
Tongue & Groove (T&G)
One flange has a raised ring (tongue); the other a matching groove. Provides excellent alignment and a confined gasket. Used in pumps and valve bonnets.
Male & Female (M&F)
Similar to T&G but the female face is flat and the male face raised. Used in heat exchangers, pressure vessels, and high-integrity process joints.
Large Male & Female
Same operating principle as the standard Male & Female flange, scaled up with larger step contact surfaces for specialized heavy industrial equipment.
Advantages & Limitations of Threaded Flange
✅ Advantages
No Welding Required
Fastest installation possible — no hot work permit, no skilled welder, no heat distortion of pipe.
ATEX / Ex Zone Safe
The ONLY standard flange type for explosive atmosphere zones where welding is strictly prohibited.
Reusable
Can be removed, inspected, re-sealed with fresh thread compound, and reinstalled repeatedly.
Fast Installation
Thread engagement takes minutes vs hours for welded joints — significant labour cost saving.
No Heat Distortion
No weld shrinkage or heat-affected zone (HAZ) to worry about — pipe dimensions unchanged after installation.
Limitations — Transparent Disclosure
Industries & Applications
✓ Primary Applications
Oil & Gas
Upstream extraction, midstream pipelines, downstream refineries.
Petrochemical
Chemical reactors, process lines, heat exchangers.
Power Generation
Boilers, steam turbines, nuclear plants, thermal power.
Pharmaceuticals
Hygienic piping, clean steam, pure water systems.
Food & Beverage
Sanitary flanges, sugar mills, beverage processing.
Paper & Pulp
Chemical recovery, bleaching lines.
Water Treatment
Municipal water, desalination, irrigation.
Shipbuilding
Offshore platforms, FPSOs, marine piping.
Chemical Plants
Acid service, caustic lines, solvent handling.
Construction
HVAC, fire suppression, utility headers.
Testing & Inspection
Zero-defect quality control — thread form gauging, visual inspection, dimensional checking, PMI, and hydrostatic testing. Thread form verified per ASME B1.20.1 or ISO 7/1 as applicable.
Hydrostatic / Hydro Pressure Test
Each flange pressure tested at 1.5x working pressure per ASME code requirements.
Ultrasonic Testing (UT)
Non-destructive testing to detect internal sub-surface cracks, inclusions and forging defects.
Radiographic Testing (RT / X-Ray)
100% radiography available; mandatory for critical Class 900+ high pressure services.
Positive Material Identification (PMI)
Spectrometer validation to verify alloy chemistry precisely matches the Mill Test Certificate.
Dye Penetrant Test (DPT / LPT)
Detects micro surface cracking and porosity on critical machined seating surfaces.
Magnetic Particle Inspection (MPI)
For ferromagnetic alloys; flags surface and near-surface structural discontinuities.
Hardness Test (Brinell/Rockwell)
Verifies correct heat treatment structure and ensures mechanical properties are hit.
Direct-Reading Spectrograph
In-house lab chemical checks of billets before forging process begins.
Impact / Charpy Test
Crucial for low-temperature applications to verify ductility (e.g. A350 LF2, LTCS).
NACE Compliance Testing
Verifies sour-gas / H2S environment service capability (NACE MR0175 / MR0103).
Documents & Certificates
Full documentation package including EN 10204 3.1 MTC, thread inspection records, and third-party inspection from SGS, Lloyd's, and DNV on request.
Mill Test Certificate (MTC)
Provided as per EN 10204 3.1 detailing chemical & mechanical analysis.
EN 10204 3.2 Certificate
Independent third-party inspection validation (available upon request).
NACE MR0175 / MR0103 Compliance
Certified suitability for sour gas/H2S environments.
Raw Materials Certificate
Provides 100% trace origin tracking from steel billet to finished flange.
Dimensional Inspection Report
All critical tolerances checked and certified against CAD designs.
Heat Treatment Certificate
HTR and PWHT thermal chart records included where requested.
Hydrostatic Test Certificate
Pressure log documentation verifying weld integrity.
Third Party Inspection (TPI)
Bureau Veritas, SGS, Lloyds, DNV, TUV inspection options.
Packing List & Weight Certificate
Proper documentation for simple custom clearance and cargo log.
Country of Origin Certificate
Enables import tariff relief and compliance logging.
Threaded Flange vs Other Flange Types
Not sure which flange suits your application? This quick comparison covers the key decision factors:
| Feature | Threaded Flange | Weld Neck | Socket Weld |
|---|---|---|---|
| Welding Required? | ❌ No welding at all | Yes — 1 butt weld | Yes — 2 fillet welds |
| ATEX / Ex Zone Safe? | ✅ Yes — primary use case | No (welding required) | No (welding required) |
| Installation Speed | Fastest (thread & seal) | Slowest (precision weld) | Moderate |
| Max Pressure Class | 600# recommended max | 2500# (all classes) | 600# preferred max |
| Cyclic / Vibration | NOT recommended | Best choice | Not recommended |
| Reusable / Dismantled? | Yes — unscrew and re-seal | No — must cut weld | No — must cut weld |
| Thread Sealant Needed? | Yes — PTFE tape or compound | No | No |
| Best For | ATEX zones, low-pressure utilities | Critical/high-pressure | General process piping |
Surface Finish & Coating Options
Anti-rust Paint
Standard protection coat applied on carbon steel flanges.
Oil Black Paint
High-grade finish offering superior long-term storage corrosion block.
Yellow Transparent Lacquer
Allows technical inspectors to visually inspect metal surface during receiving.
Zinc Plated
Electro-galvanized bright zinc barrier layer for light industrial environments.
Hot Dip Galvanized (HDG)
Thick zinc alloy barrier layer for maximum outdoor marine rust protection.
Epoxy Coating
FBE or liquid epoxy coating for heavy buried pipelines and sewage lines.
Bare/Pickled & Passivated
Chemical acid cleaning to restore corrosion resistance for stainless steel.
Custom Coating
Special finishes customized exactly to customer painting specifications.
Export Markets
Global Export Network
Why Choose Remax Forge?
Remax Forge & Fittings stands out as a leading flange manufacturer due to our complete in-house forging, heat treatment, and precision CNC machining capabilities based in Mumbai. We provide certified compliance, factory-direct wholesale pricing, and custom forging schedules tailored to your engineering blueprints. With over 20 years of manufacturing experience, zero-defect quality management, and short lead times, we are a trusted supply partner for critical industrial piping projects.
ISO 9001:2015 Certified
Fully audited quality management workflows.
In-House Forging
Forging, heat-treat, machining in Mumbai.
Testing Laboratory
PMI, Spectro, UT, Hydro labs on-site.
Mill Certificates
EN 10204 3.1 standard; 3.2 available.
20+ Years Experience
Serving critical gas/oil clients globally.
45+ Export Countries
Proven global logistics and documentation.
Custom Forging
Special shapes, alloys and schedules.
Factory-Direct Price
Competitive pricing with no agent markup.
Technical Support
Engineers ready to assist spec selection.
Short Lead Times
Fast turnaround of custom and stock orders.
📥 Download Threaded Flange Catalogue (PDF)
Complete technical catalogue including NPT/BSP dimension tables, material grades, standards, and thread specification data.
How to Order
Ordering high-quality forged flanges from Remax is straightforward. To ensure our engineering team provides you with a precise and competitive quote, please specify the exact flange type, nominal pipe size (NPS), pressure class rating, material grade, and facing configuration. Let us know your total quantity requirements and if you require any specialized testing or custom coatings. Contact us via email or phone for a quick, same-day response.
Direct Inquiries
Estimated Lead Times
Frequently Asked Questions
Common questions about Threaded Flanges — NPT vs BSP, high-pressure steam, seal welds, thread sealants, and special alloy availability.
Related Products
Compare our complete range of industrial flanges for your piping project.
Slip On Flange
Slides over pipe. Cost-effective and simple.
Weld Neck Flange
Tapered neck for high pressure and temperature service.
Blind Flange
Bolts onto line to isolate sections securely.
Socket Weld Flange
Shoulder socket. Great for high-pressure small lines.
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