Threaded (Screwed) Flanges Supplier in India

Flanges that screw onto a threaded pipe end, with no welding. Ideal for galvanized lines and areas where hot work is restricted. NPT or BSP taper threads in MS, galvanized, carbon steel and stainless steel.

NPT or BSP (BSPT)MS, GI, A105, SS 304 / 316ASME B16.5 / Table E½" to 6"No weldingFor GI pipe lines
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Threaded flange drawing with taper thread in the bore and threaded pipe end
The taper thread in the flange bore seals against the threaded pipe end.

When a threaded flange makes sense

A threaded flange has a taper pipe thread cut into its bore. It screws onto a threaded pipe end, so the joint needs no welding. That keeps the zinc coating on galvanized pipe intact, and it allows flanged connections in areas where welding is not permitted.

Threaded joints are made for low to moderate pressure at ordinary temperatures. Under high temperature, vibration or bending loads, threads can loosen and leak. Some specifications allow a seal weld over the thread for extra security.

When a threaded flange makes sense: specification summary
MaterialsMS IS 2062 (black or galvanized); carbon steel ASTM A105; stainless ASTM A182 F304 / F316
ThreadsNPT to ASME B1.20.1, or BSP taper (BSPT) to ISO 7-1 / IS 554
StandardsASME B16.5 Class 150 and 300; BS 10 Table D / E; IS 6392
Sizes½" to 4" commonly; up to 6" on request
FacingRaised face or flat face
FinishBlack, hot-dip galvanized, or pickled (SS)

NPT or BSP: get the thread right

NPT and BSP threads look similar but do not seal together. Mixing them leaves a leak path even when the joint feels tight.

NPTBSP taper (BSPT)
StandardASME B1.20.1ISO 7-1 / IS 554
Thread angle60°55°
Common onAmerican-pattern equipment, ASME B16.5 flangesIndian GI and MS pipes to IS 1239

Indian GI pipes are normally threaded BSP to IS 554, so a BSP-threaded flange is the usual match. Read our GI pipe guide for IS 1239 sizes and classes.

Assembly tips

  1. Check that the pipe thread and flange thread are the same type and size.
  2. Use a thread sealant or PTFE tape suited to the fluid and temperature.
  3. Screw the flange on and tighten until the bolt holes line up with the mating flange; do not back it off to align holes.
  4. Bolt the flanges evenly in a cross pattern.

Where not to use threaded flanges

Avoid threaded flanges on high-temperature lines, lines with vibration or large bending loads, and hazardous fluids unless your specification allows them, usually with a seal weld. For those services, use socket weld or weld neck flanges.

Where threaded flanges are used

  • Galvanized water supply and plumbing lines
  • Fire-fighting sprinkler and hydrant branches
  • Compressed air and low-pressure gas lines
  • Plants and areas where hot work permits are hard to get
  • Small pump and equipment connections

Pipes and fittings to go with threaded flanges

Pipe or fittingUse it with these flanges when…
GI pipes (IS 1239)the line is galvanized and threaded
ERW pipesyou need black MS pipe with threaded ends
SS round pipesthe line is stainless and threaded
Threaded couplings and fittingsyou need sockets, elbows and tees for the same line
Fitting out a GI water line?Send pipe sizes and lengths. We quote GI pipe, threaded flanges and fittings together.
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Flange types we supply

Each page covers materials, standards, sizes and where that flange fits. All flanges can be quoted with matching pipes and fittings.

MS Flanges drawingMS FlangesIS 2062 mild steel, Table E / IS 6392 / ASA 150 Stainless Steel Flanges drawingStainless Steel FlangesSS 304, 304L, 316, 316L to ASME B16.5 Carbon Steel Flanges drawingCarbon Steel FlangesForged ASTM A105, A350 LF2, Class 150 to 1500 Slip-On Flanges (SORF) drawingSlip-On Flanges (SORF)Pipe slides in, two fillet welds Weld Neck Flanges (WNRF) drawingWeld Neck Flanges (WNRF)Butt-welded, bored to pipe schedule Blind Flanges drawingBlind FlangesClose pipe ends, nozzles and test points Socket Weld Flanges drawingSocket Weld FlangesSmall-bore, high-pressure lines Threaded Flanges drawingThreaded FlangesNPT / BSP, no welding, GI lines Lap Joint Flanges drawingLap Joint FlangesLoose flange with stub end Plate Flanges drawingPlate FlangesFlat flanges, Table D/E/F/H, custom Flange Size & Class Chart drawingFlange Size & Class ChartASME B16.5 OD, PCD, bolts and ratings
FAQ

Frequently Asked Questions

A threaded flange, also called a screwed flange, has a taper pipe thread in its bore and screws onto a threaded pipe end, so no welding is needed.

NPT threads have a 60° angle and follow ASME B1.20.1; BSP taper threads have a 55° angle and follow ISO 7-1 or IS 554. They are not interchangeable. Indian GI pipes are usually BSP.

Yes. A galvanized, BSP-threaded flange is the usual way to make a flanged joint on IS 1239 GI pipe without damaging the zinc coating by welding.

It depends on the class or table, material, size and temperature, but threaded joints are generally limited to low and moderate pressure at ordinary temperatures. Follow your piping specification.

A seal weld is a small fillet weld over the thread engagement that seals the joint. It is used where a threaded flange is allowed but extra leak-tightness is needed.

Commonly ½" to 4", and up to 6" on request, in MS, galvanized, A105 and stainless steel.

Buyer Guides & Tools

Flange Size Chart & Pressure ClassesASME B16.5 OD, PCD, bolts, Class 150 to 2500ERW vs Seamless PipeWhich pipe to use with your flangesPipe & Tube Weight CalculatorMS / SS / GI round, square & rectangularSteel Pipe Buying Guide for IndiaChecklist before you request a quoteSS 304 vs SS 316Choosing the stainless grade
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Get a Flange Quote

Tell us the flange type, size, class or table, material and quantity. We reply on call, WhatsApp or email.

  • MS, carbon steel and stainless steel flanges on one quotation
  • Matching pipes, elbows, tees and reducers from the same order
  • Dispatch from Thane / Panvel to sites across India
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