Pipe flange types are selected according to connection method, pressure class, maintenance needs and installation space. A correct flange choice improves sealing performance and makes inspection or disassembly easier during pipeline operation.
Common pipe flange types
Blind flanges close the end of a piping system or pressure vessel opening. Slip-on flanges are commonly used for easier alignment and welding. Socket weld flanges are used for smaller high-pressure piping. Threaded flanges can be installed without welding in suitable services. Lap joint flanges are useful where frequent dismantling or alignment adjustment is required.
Material selection
Carbon steel flanges are widely used in general piping. Stainless steel flanges are suitable for corrosive media or clean service. Alloy steel flanges may be selected for high temperature, high pressure or special process conditions.
Standards and dimensions
Buyers should confirm flange standard, nominal size, pressure class, face type, bolt hole pattern, thickness and sealing surface. Flat face, raised face and ring type joint designs may be required depending on the gasket and pressure service.
Related product pages
See the main pipe flanges category, or compare with pipe elbows, pipe tees and reducers. Send drawings or specifications through the contact page.
Further Reading
You may also find these guides helpful:
Choosing the Right Flange Type – Decision Guide
High pressure or high temperature? Weld neck – the tapered hub carries stress and the full-penetration butt weld is as strong as the pipe. Low pressure, cost-sensitive water/air lines? Slip-on – easier alignment, two fillet welds, cheaper. Terminating a line or a vessel nozzle? Blind. Small bore instrument lines below 2″? Socket weld. No welding allowed (explosive areas, threaded pipe)? Threaded. Frequent dismantling or alignment adjustment? Lap joint with stub end.
Facing Types in Brief
RF (raised face) is the default for process piping – a soft or spiral-wound gasket seats on the raised ring. FF (flat face) pairs with cast iron equipment to avoid cracking – full-face gasket only. RTJ (ring type joint) seals metal-to-metal for class 900+ hydrocarbon and steam service. MFM (male-female) and TG (tongue-groove) confine the gasket – used on valve bonnets, exchanger heads and pumps. Both mating flanges must use the same facing style.
Material Selection Basics
A105 carbon steel covers most ambient-temperature water, oil, steam and air service. A350 LF2 is the low-temperature carbon grade for winter and refrigeration service down to -46°C. A182 F304/F304L stainless for corrosive and food-grade lines; F316/F316L adds molybdenum for chloride resistance. Alloy F11/F22 for high-temperature steam. Match the flange material to the pipe material (or one grade higher in corrosion allowance).
FAQs
Which flange type is strongest? Weld neck – its hub and butt weld distribute stress like the pipe itself; it is required for severe cyclic, high pressure and high temperature service.
Can I mix slip-on and weld neck in one joint? Technically the bolt patterns match, but good practice keeps fitting types consistent per line class – follow your line specification.
Full comparison with photos: Flange Types Guide.