Flanges
Flanges are Forged or Cast Steel Rings used to connect Pipes, Valves and Pumps forming a Piping System that allows for easy Cleaning, Inspection or Modification. They are attached via Welding, Threading or Bolting often using Gaskets to ensure a Tight Seal. Key standards include ASME B16.5 with common types being Weld Neck, Slip-On and Blind.
Key Types of Flanges:
- Weld Neck Flange:Features a Long Tapered Hub designed for High-Pressure and High-Temperature applications.
- Slip-On Flange:Slips over the Pipe allowing for easier Alignment and Lower Cost.
- Blind Flange:A solid Disk with no Bore used to Blank off Pipeline Ends or Openings.
- Socket Weld Flange:Used for Small-Diameter, High-Pressure Piping.
- Threaded Flange:Assembled without Welding suitable for specialized low-pressure applications.
- Lap Joint Flange:Used with a Stub End ideal for systems requiring frequent dismantling.
Flange Facing Types:
- Raised Face (RF):Features a Small Raised section around the Bore common for higher pressure applications.
- Flat Face (FF):Used when Mating Materials are Brittle.
- Ring Type Joint (RTJ):Features a Metal Ring Gasket to maintain a seal under High-Pressure and High-Temperature conditions.
- Tongue & Groove (T&G):Self-Aligning and provides a secure seal.
Pressure-Temperature Ratings:
Flanges are classified by pressure-temperature ratings (ASME B16.5) and are commonly rated in pressure classes such as:
- 150lb, 300lb, 600lb, 900lb, 1500lb and 2500lb.
Common Materials and Sizes:
- Materials:Forged Carbon Steel (ASTM A105), Low-Alloy Steel (ASTM A350), Stainless Steel (ASTM A182) and Duplex Steel.
- Sizes:Typically range from 1/2 inch to 24 inches (nominal pipe size).
- Dimensions:Include the Pitch Circle Diameter (PCD), Bolt Size, Hub Diameter and outer Diameter.
Flange Marking:
Flanges are marked to identify their specifications including:
- Nominal Size
- Pressure Class
- Material Grade
- Manufacturer’s Mark
- Batch Number