Slip-On Flanges (SORF) Supplier & Stockist in India

The most widely used flange for utility and process piping: the pipe slides through the bore and is fillet-welded inside and out. Supplied in MS, carbon steel A105 and stainless steel.

SORF / SOFFASME B16.5 Class 150 / 300Table E / IS 6392MS, CS A105, SS 304 / 316½" to 24"Hubbed or plate

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Slip-on flange drawing with pipe through bore and two fillet welds — The pipe end sits just inside the flange face and is welded at the hub and at the bore.

How a slip-on flange works

A slip-on flange has a bore slightly larger than the pipe's outside diameter. The pipe slides in, the flange is squared up, and it is welded with one fillet weld at the back (on the hub) and one inside, near the face. No precise cutting or bevelling is needed, which makes slip-ons quicker to fit than weld neck flanges.

Slip-on flanges are commonly quoted as having about two-thirds the strength of a weld neck flange under internal pressure and about one-third of its fatigue life. That is plenty for water, air and most Class 150 and 300 process lines, but not for heavy cyclic or high-temperature service.

How a slip-on flange works: specification summary
Materials	MS IS 2062; carbon steel ASTM A105; stainless ASTM A182 F304 / F304L / F316 / F316L
Standards	ASME B16.5 Class 150 and 300 (600 on request); BS 10 Table D / E / F / H; IS 6392; EN 1092-1
Sizes	½" (15 NB) to 24" (600 NB)
Facing	Raised face (SORF) or flat face (SOFF)
Construction	Hubbed (forged) or plate (no hub)
Bore	Sized to the pipe OD; state the pipe OD with the NB size
Welding	Two fillet welds: outside at the hub and inside at the bore

Fitting a slip-on flange

Slide the flange on with the face toward the mating flange.
Set the pipe end back from the flange face so the inside weld does not reach the gasket face. Your piping specification or welding procedure gives the exact setback.
Square the flange to the pipe and align bolt holes with the mating flange (holes straddle the centre line).
Weld the outside fillet at the hub, then the inside fillet at the bore.
Clean the face and check it is flat before fitting the gasket.

Slip-on vs weld neck

	Slip-on	Weld neck
Cost	Lower	Higher (more forging, machining)
Fit-up	Easy; pipe length less critical	Pipe cut and bevelled to length
Welds	Two fillet welds	One full-penetration butt weld
Strength and fatigue	Lower	Highest of common flange types
Inspection	Surface checks (DP / MPI)	Butt weld can be radiographed
Typical service	Water, air, utilities, moderate process lines	High pressure, high temperature, cyclic or hazardous

If your line needs the stronger option, see weld neck flanges.

Hubbed slip-on or plate slip-on?

An ASME B16.5 slip-on is forged with a short hub on the back, which stiffens the flange and gives more length for the outside weld. A plate flange is a flat slip-on with no hub, usually cut from plate and drilled to Table E or IS 6392. Plate slip-ons cost less and are standard on low-pressure MS lines.

Where slip-on flanges are used

Cooling water, fire water and potable water lines
Compressed air and utility headers
HVAC chilled and condenser water
Low and moderate pressure process lines (Class 150 and 300)
Pump suction and discharge on utility pumps

Pipes and fittings to go with slip-on flanges

Pipe or fitting	Use it with these flanges when…
ERW pipes	you are building water, air or utility lines
MS round pipes	you need black MS pipe in standard OD
Carbon steel pipes	the flange is A105 on a process line
SS seamless pipes	the line is stainless
Elbows, tees and reducers	you need fittings for the same run

Ordering slip-on flanges in bulk?Share size range, material, drilling and quantities for one consolidated rate.

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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 FlangesIS 2062 mild steel, Table E / IS 6392 / ASA 150

Stainless Steel FlangesSS 304, 304L, 316, 316L to ASME B16.5

Carbon Steel FlangesForged ASTM A105, A350 LF2, Class 150 to 1500

Slip-On Flanges (SORF)Pipe slides in, two fillet welds

Weld Neck Flanges (WNRF)Butt-welded, bored to pipe schedule

Blind FlangesClose pipe ends, nozzles and test points

Socket Weld FlangesSmall-bore, high-pressure lines

Threaded FlangesNPT / BSP, no welding, GI lines

Lap Joint FlangesLoose flange with stub end

Plate FlangesFlat flanges, Table D/E/F/H, custom

Flange Size & Class ChartASME B16.5 OD, PCD, bolts and ratings

FAQ

Frequently Asked Questions

SORF means slip-on raised face: a slip-on flange with a raised face for the gasket. SOFF is the flat-face version, used against cast iron or FRP equipment.

Yes. A slip-on is normally welded with an outside fillet weld at the hub and an inside fillet weld at the bore, near the face.

Avoid slip-on flanges in severe cyclic service, large temperature swings, very high pressure or where the piping specification calls for weld neck flanges. Use a weld neck flange instead.

A plate flange is a flat slip-on flange without a hub. It slides over the pipe and is welded the same way, but it is usually cut from plate and used for lower pressures.

The bore is slightly larger than the pipe outside diameter. Tell us the pipe OD (for example 60.3 mm for 2" NB) so the flange fits your pipe without a large gap.

MS slip-on flanges in Table E and ASA 150 drilling, and forged A105 and SS slip-on flanges to ASME B16.5. Sizes from ½" to 24".

Buyer Guides & Tools

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

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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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