Industrial Flange Types: Selection Guide for Piping Professionals

Introduction to Industrial Flanges

Flanges are the backbone of industrial piping systems, providing the connective tissue that joins pipes, valves, pumps, and equipment. Selecting the right flange type is critical for system integrity, safety, and maintainability.

Songhai Flange, established in 1994, manufactures precision flanges to ASME, DIN, JIS, GB, and other international standards. This guide covers the essential flange types every piping professional should know.

Flange Types by Connection Method

Фланцы со сварной горловиной

Weld neck flanges feature a long tapered hub that butt-welds to the pipe. This is the premium choice for critical applications.

Advantages:

  • Superior stress distribution at weld joint
  • Reduced stress concentration
  • Ideal for high pressure and temperature
  • Excellent for cyclic loading conditions
  • Full penetration weld provides leak-proof connection

Applications: Refineries, power plants, offshore platforms, high-pressure process lines

Slip-On Flanges

Slip-on flanges slide over the pipe and are welded both inside and outside. They’re cost-effective for lower-pressure applications.

Advantages:

  • Lower initial cost than weld neck
  • Easier alignment during installation
  • Shorter lead time
  • Sufficient for most general service

Applications: Water systems, low-pressure process lines, utility piping

Приварные фланцы

Socket weld flanges have a recessed bore for pipe insertion and a single external fillet weld. Used primarily for small-diameter piping.

Applications: Instrument lines, hydraulic systems, small-bore high-pressure piping

Резьбовые фланцы

Threaded flanges have internal NPT threads for screw-on installation without welding.

Advantages:

  • No welding required
  • Quick installation and removal
  • Ideal for explosive environments

Applications: Low-pressure water, air, gas lines; instrument connections

Фланцы с нахлестом

Lap joint flanges are used with stub ends. The flange rotates freely around the pipe, facilitating bolt hole alignment.

Applications: Piping requiring frequent maintenance, lined pipe systems

Слепые фланцы

Blind flanges close off pipe ends, valve openings, or pressure vessel nozzles. They have no bore center.

Flange Face Types

Raised Face (RF)

The most common face type. The raised portion concentrates gasket pressure for better sealing.

Flat Face (FF)

Entire face is flat, used with flat gaskets. Required when mating with cast iron equipment.

Ring Type Joint (RTJ)

RTJ flanges have a groove for metal ring gaskets. Used for high-pressure, high-temperature service.

Flange Standards

ASME B16.5

The North American standard for pipe flanges and flanged fittings.

  • Size range: 1/2″ to 24″
  • Pressure classes: 150, 300, 400, 600, 900, 1500, 2500

DIN/EN Standards

  • DIN 2501 / EN 1092-1: European flange standard
  • PN ratings: PN6, PN10, PN16, PN25, PN40

JIS B2220

Japanese Industrial Standard for flanges.

  • 5K, 10K, 16K, 20K, 30K ratings

GB/T Standards

Chinese national standards for flanges.

  • GB/T 9112-9124: Steel pipe flanges

Material Selection Guide

Carbon Steel

  • A105: Forged carbon steel, most common
  • A350 LF2: Low-temperature service

Stainless Steel

  • A182 F304/F304L: General corrosion resistance
  • A182 F316/F316L: Marine and chemical service

Conclusion

Selecting the right flange type ensures safe, reliable, and maintainable piping systems. Consider pressure, temperature, fluid properties, maintenance requirements, and applicable codes when making your selection.

Songhai Flange manufactures all flange types in carbon steel, stainless steel, alloy steel, and special materials. Our ISO 9001:2008 certified facility ensures consistent quality and full traceability.
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