Industrial Stainless Steel (SS) Flanges

Common Types of Stainless Steel Flanges

• Weld Neck Flanges (WN): Designed with a tapered hub butt-welded to the pipe. Ideal for severe, high-pressure, and elevated-temperature service.

• Slip-On Flanges (SO): Slipped over the pipe and fillet-welded on both the inside and outside. Offers lower installation costs and easy alignment.

• Blind Flanges (BL): Manufactured without a center bore to seal off pipe ends, valves, or pressure vessel openings.

• Socket Weld Flanges (SW): Features a socket bore to receive the pipe end before fillet welding. Best suited for small-bore, high-pressure lines.

• Threaded Flanges (TH): Machined with internal NPT threads to connect with male-threaded pipes without welding.

• Lap Joint Flanges (LJ): Used alongside a lap joint stub end to allow 360-degree rotation for fast alignment of bolt holes during installation.

Popular Material Grades & Specifications

Stainless steel flanges are supplied in austenitic and duplex grades to meet specific operational demands:

• SS 304 / 304L: Standard grade offering excellent corrosion resistance, high weldability, and economical performance for general industrial applications.

• SS 316 / 316L: Formulated with 2–3% molybdenum for superior resistance against pitting and crevice corrosion in marine and chemical environments.

• SS 321 / 347: Titanium or Niobium stabilized grades designed to prevent intergranular corrosion under high operational temperatures (800°F–1500°F).

• Duplex SS (S31803 / S32205): Offers double the mechanical yield strength of standard austenitic grades and outstanding stress-corrosion cracking resistance.

Technical Specifications Summary

• Standard Dimensions: ANSI / ASME B16.5, ASME B16.47 (Series A & B), BS 4504, DIN 2501, EN 1092-1, JIS B2220

• Size Range:

  Nominal Pipe Size (NPS / DN) Conversion Chart

  • 1/2" (DN15): Suitable for small-bore instrument lines and fluid sampling setups.

  • 3/4" (DN20): Ideal for auxiliary utility piping and compact pneumatic systems.

  • 1" (DN25): Standard size for process lines, pump inlets, and chemical feeds.

  • 1-1/4" (DN32): Widely used in water distribution and specialized machinery piping.

  • 1-1/2" (DN40): Fits industrial steam, oil, and processing lines.

  • 2" (DN50): Highly common size across commercial and industrial fluid transport.

  • 2-1/2" (DN65): Used in fire protection, cooling towers, and HVAC systems.

  • 3" (DN80): Standard size for main distribution lines and vessel connections.

  • 4" (DN100): High-demand size for municipal water, oil refineries, and chemical plants.

  • 5" (DN125): Medium-bore line size for specialized heavy-duty flow systems.

  • 6" (DN150): Common size for process manifolds and heavy industrial supply networks.

  • 8" (DN200): Designed for main trunk lines and high-volume fluid transport.

  • 10" (DN250): Heavy industrial size for plant headers and power generation facilities.

  • 12" (DN300): Large-bore size for primary pipeline infrastructure and processing plants.

• Pressure Ratings (ANSI): Class 150, 300, 600, 900, 1500, 2500

• Pressure Ratings (PN / DIN): PN6, PN10, PN16, PN25, PN40, PN64

• Flange Facing Types: Raised Face (RF), Flat Face (FF), Ring Type Joint (RTJ), Male & Female (M&F), Tongue & Groove (T&G)

• Manufacturing Methods: Precision Forged, Heat Treated, Fully CNC Machined

Key Applications

• Chemical & Petrochemical Processing Facilities

• Oil & Gas Exploration and Off-shore Refineries

• Food, Beverage, and Sanitary Dairy Production

• Pharmaceutical Manufacturing Equipment

• Water Treatment, Desalination, and Power Generation Plants]