Steel Flanges
Forged, Plate, or Custom. Every Steel Flange Type.
The full steel flange catalog out of one supplier. Forged ASME B16.5 from 1/2 inch through 24 inch. ASME B16.47 and MSS SP-44 large-diameter forgings. Plate-cut AWWA C207 rings and structural flanges through 203 inch. Carbon through chrome-moly. If a steel flange exists, it lives somewhere on this page.
Catalog
Every Flange Type
The twelve flange types below cover essentially every piping isometric, vessel nozzle, and waterworks tap that comes through the quote desk. Anything truly one-off lives on the custom machining page.
Weld Neck
The workhorse for high pressure, high temperature, and cyclic service. Long tapered hub transfers stress from the flange ring into the pipe wall. Specified for most process, pipeline, and refinery work.
Slip-On
Slides over the pipe and is fillet welded on both sides. Lower cost than weld neck, easier alignment, but lower fatigue rating. Common on utility, lower-pressure process lines, and large-diameter water service.
Blind
Solid flange used to close the end of a pipe, valve, or vessel nozzle. Frequently drilled and machined later for instrumentation. Stocked in all standard classes and materials, plate-cut for large diameter.
Threaded
NPT threaded bore for piping that cannot be welded. Common on small bore utility lines, instrument connections, and hazardous-area piping where welding is restricted.
Socket Weld
Pipe drops into a counterbore and is fillet welded on the outside. Used on small bore high-pressure lines typically 2 inch and below. Sized to ASME B16.5.
Lap Joint
Used with a stub end so the flange can rotate for bolt-hole alignment. Common in stainless and exotic alloy systems where the lap joint flange itself can be carbon to save cost.
Reducing
Single flange that reduces from one size to another without an additional reducer fitting. Useful when space is tight or schedule is critical.
Orifice
Paired flanges with tapped pressure connections for orifice plate flow measurement. Stocked in weld neck and slip-on configurations across standard classes.
Spectacle Blind
Figure-8 plate with a blind on one end and a spacer ring on the other. Pivots between positions for positive isolation during maintenance and turnarounds. Plate-cut in large sizes.
Long Weld Neck
Extended neck used as a nozzle on pressure vessels and column trays. Bored to match vessel wall thickness rather than standard pipe schedule.
Plate
Flat plate flange machined from rolled plate. Cost-effective for large-diameter, lower-pressure service such as water distribution, HVAC, and structural connections through 203 inch.
Ring-Type Joint
RTJ facing with metal ring gasket for high-pressure and high-temperature sealing. Standard on Class 900 and above when service conditions demand metal-to-metal sealing.
Production Paths
Forged vs Plate
Two production paths cover the steel flange universe. Forged flanges start as a heated billet, hammered or pressed into ring form, then machined to spec. Plate flanges start as rolled steel plate, profile-cut and drilled. Which one a project needs depends on pressure, diameter, and what the relevant standard allows.
Forged
The grain flow of the parent material is preserved and oriented along the load path. Required for all ASME B16.5 pressure service, all API wellhead service, and anywhere a hub geometry is needed - which is to say, anywhere a weld neck or slip-on lives.
Standard size range is 1/2 inch through 24 inch in B16.5. ASME B16.47 and MSS SP-44 extend forged production through 60 inch in large-diameter applications.
Plate
Profile-cut from rolled steel plate. Cost-effective for large-diameter, lower- pressure service. Acceptable under AWWA C207 for waterworks, and widely used on blind flanges, structural connections, and custom geometries where no forging exists.
Plate production opens the door to sizes that forged simply cannot reach. Custom plate-cut flanges go through 203 inch outside diameter when a job requires it.
For pressure piping, the standard dictates which path is allowed. AWWA C207 explicitly permits plate. ASME B16.5 does not. When in doubt, send the spec.
Process
ASME B16.5 and B16.47
The two standards that cover the bulk of refinery, petrochemical, midstream, and general process piping. B16.5 handles 1/2 inch through 24 inch. B16.47 picks up at 26 inch and runs through 60 inch in Series A and Series B, each with its own dimensional family.
ASME B16.5 - 1/2 in through 24 in
Pressure classes 150, 300, 400, 600, 900, 1500, and 2500. Standard facings include raised face, flat face, and ring-type joint. Materials from A105 carbon up through stainless, low-temp, and chrome-moly alloy steels.
B16.5 reference ->ASME B16.47 - 26 in through 60 in
Series A (formerly MSS SP-44) and Series B (formerly API 605) cover large diameter. Different outside diameters and bolt patterns between the two, so always confirm which series the line was originally designed to before sourcing replacements.
B16.47 reference ->Pressure-temperature ratings drop as temperature rises. A Class 300 carbon steel flange rated at 740 psi at ambient is rated closer to 535 psi at 700 F. The B16.5 tables are the source of truth. If you need a copy of the rating curves, ask and we will send them.
Waterworks
AWWA C207 and Plate-Cut Rings
Waterworks, fire protection, low-pressure process, and HVAC distribution do not need a forged Class 1500 flange. AWWA C207 covers ring and hub flanges sized for water service from 4 inch up through 144 inch in Class B, D, and E (Class F is published only through 48 inch). Above 144 inch is fully custom plate fabrication outside any published standard; dimensions, drilling, and pressure rating are project-specific. Bolt patterns on Class B, D, and E match ASME B16.1 Class 125 for sizes 24 inch and under so retrofits do not require ripping out mating flanges.
AWWA C207 Pressure Ratings
Above 144 inch the published standard ends and the work becomes fully custom plate fabrication. Dimensions, drilling, and pressure rating are project-specific and not governed by any published flange code. We have coordinated plate-cut work through 203 inch outside diameter in carbon steel and structural grades on prior projects. Drilling, facing, and surface prep all per the engineering drawing.
Materials
A105 Through F91
Material selection drives more headaches than dimensional selection. The list below covers the bulk of what crosses our quote desk on steel flange orders. Anything not listed, ask.
Carbon and Low Temp
A105 - standard forged carbon for ambient and moderate temperature.
A350 LF2 - low-temperature carbon, impact tested to -50 F.
A36 / A516 plate - plate-cut grades for AWWA and structural work.
A694 F52 through F70 - high-yield pipeline grades for transmission service.
Carbon steel detail ->Stainless
F304 / F304L - general-purpose austenitic stainless.
F316 / F316L - molybdenum-bearing for improved chloride resistance.
F321, F347 - stabilized grades for elevated temperature.
Stainless detail ->Chrome-Moly Alloy
F11 (1-1/4 Cr) - moderate elevated temperature service.
F22 (2-1/4 Cr) - hydrogen and high-temp refinery service.
F91 (9 Cr) - high-pressure steam, power generation, and creep- critical service.
Alloy steel detail ->Exotic
Duplex 2205, Super Duplex 2507 - offshore and sour service.
Inconel 625, 825 - high-temperature corrosion resistance.
Hastelloy C276, Monel 400, Titanium Gr 2 - specialty service.
Exotic alloys detail ->Size Range
1/2 Inch Through 203 Inch
Steel flanges run the full range of pipe and vessel sizes used in industrial and municipal service. Forged sizes track the ASME and MSS standards. Plate-cut sizes extend well past where forging stops, all the way to 203 inch on custom diameters coordinated through partner plate-cut fabricators.
Technical Resources
Read Before You Specify
Reference content from our technical library. Useful when reviewing a line list or when the standard in question is not the one you specify every day.
- The Complete Guide to Flanges - types, facings, ratings, and selection logic.
- AWWA C207 Reference - lightweight pressure classes and drilling.
- ASME B16.5 / B16.47 Reference - dimensions, facings, and material groups.
- Pressure-Temperature Calculator - find the derated pressure at your service temp.
Send the Line List
Email a BOM, an isometric, or a take-off and we will price it against current stock and confirm lead times for anything that ships from the mill.