Carbon Steel Flanges Supplier & Stockist in India

Forged CS flanges for pressure piping: ASTM A105 for general service, A350 LF2 for low temperature and A694 for high-yield pipelines, made to ASME B16.5 Class 150 to 1500.

ASTM A105 / A105NA350 LF2ASME B16.5Class 150 to 1500RF / FF / RTJ½" to 24"
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Carbon steel A105 weld neck flange drawing with butt weld
Forged A105 weld neck flanges are the default for carbon steel pressure piping.

Forged carbon steel flanges for pressure piping

Carbon steel flanges join pipes, pumps and vessels in steam, oil, gas, compressed air and process lines. For pressure piping, the usual material is forged ASTM A105, made to the dimensions and pressure classes of ASME B16.5. Forging gives a dense, consistent structure that plate-cut flanges cannot match.

We supply CS flanges with carbon steel pipes in A106 Grade B, A53 and API 5L, plus seamless pipes and fittings, so material grade and schedule stay consistent across the line.

Forged carbon steel flanges for pressure piping: specification summary
GradesASTM A105 / A105N; A350 LF2 for low temperature; A694 F42 to F65 on request; A516 Gr 70 or IS 2062 plate for low pressure
TypesWeld neck, slip-on, blind, socket weld, threaded, lap joint; long weld neck on request
StandardsASME B16.5 (½" to 24"); ASME B16.47 for larger sizes to order; EN 1092-1; IS 6392
Pressure classes150, 300, 600, 900, 1500; 2500 on request
FacingRF, FF, RTJ
FinishAnti-rust oil or varnish; hot-dip galvanized on request
Marking and documentsGrade, class, size and heat number; mill test certificate on request

Pressure class and working pressure

The class number is not the working pressure in psi. It is a rating step, and the allowed pressure depends on the material and temperature. For ASTM A105 (ASME B16.5 material group 1.1) between −29 °C and 38 °C, the ratings are:

ClassMax. working pressure (bar)Max. working pressure (psig)
15019.6285
30051.1740
40068.1990
600102.11480
900153.22220
1500255.33705
2500425.56170

These ratings fall as temperature rises. For a steam or hot oil line, check the ASME B16.5 table at your design temperature. Our flange size and class guide explains the tables and lists Class 150 and 300 dimensions.

A105, LF2 or A694: which grade?

GradeUse it forNotes
ASTM A105 / A105NGeneral pressure piping, ambient to elevated temperatureMost common CS flange. A105N is normalized.
ASTM A350 LF2Low-temperature serviceImpact tested at low temperature, used for cold climates, LPG and refrigerated lines
ASTM A694 F42 to F65High-yield transmission pipelinesMatched to high-strength API 5L line pipe
A516 Gr 70 / IS 2062 plateLow-pressure plate or blind flangesNot a substitute for forged flanges in pressure service

Choosing the flange type in carbon steel

Use weld neck flanges for high pressure, temperature swings or vibration, because the tapered hub and butt weld carry stress best. Slip-on flanges are cheaper and easier to fit for moderate service. Socket weld flanges suit small-bore high-pressure lines, and blind flanges close line ends and nozzles.

Where carbon steel flanges are used

  • Refineries, petrochemical and fertilizer plants
  • Steam, condensate and boiler feed lines
  • Oil, gas and LPG pipelines and skids
  • Compressed air and nitrogen headers
  • Fire water networks in industrial plants
  • Pump and compressor connections

Pipes and fittings to go with CS flanges

Pipe or fittingUse it with these flanges when…
Carbon steel pipes (A106, A53, API 5L)you need schedule pipe in a matching CS grade
MS seamless pipesthe line is seamless for pressure or temperature
Boiler pipes and tubesthe flanges are on steam or boiler lines
Heavy wall pipesyou need Sch 160 or XXS walls with high-class flanges
Butt-weld elbows, tees and reducersyou need ASME B16.9 fittings for the same line
Pricing a CS piping package?Send the flange list with class, schedule and grade. We quote pipes and fittings too.
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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

ASTM A105 is the standard specification for carbon steel forgings for piping components. A105 flanges are the default carbon steel flanges for ASME B16.5 pressure piping at ambient and elevated temperatures.

A105N is A105 material supplied in the normalized heat-treated condition. Many project specifications ask for A105N for more consistent toughness.

It depends on the design pressure, design temperature and material. For A105 at up to 38 °C, Class 150 is rated 19.6 bar and Class 300 is rated 51.1 bar. Your piping specification gives the required class.

Both are carbon steel, but in trade “CS flange” normally means a forged A105 flange to ASME B16.5 for pressure service, while “MS flange” means a plate-cut IS 2062 flange for low-pressure lines.

Ring type joint (RTJ) facing is available on request for weld neck and blind flanges in higher classes. Tell us the ring number or class and size.

Yes. We supply A106, A53 and API 5L pipes, butt-weld fittings and CS flanges together so grades and schedules match.

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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