A gasket is a material that is used to seal the face of flanges, valves and equipment. Gaskets can be made from materials that are soft or hard, but will compress to make a tight seal. When compressed between two flange faces it will deform to match the surface grooves and irregularities. A gasket must be installed properly to prevent leakage. The surface of the flange must be clear of all foreign bodies such as dust, dirt or grease that could prevent a proper seal. To ensure a seal through out the life of the gasket, sufficient pressure or stress should be maintained to prevent leakage. It is very important to select the right gasket material to be used.

Types of Gaskets

• Gasket materials can be divided into three basic categories:
  • Non-metallic gaskets or "soft gaskets" are made from materials that are easily compressed under a low bolt load. They can be used with both flat and raised face flanges in low pressure applications. Materials used are different types of rubber, PTEF, ceramic fiber, glass fiber and more. ASME B16.21 - Nonmetallic Flat Gaskets for Pipe Flanges
  • Semi-metallic gaskets are made from both non-metallic and metallic materials and can operate at both high temperature and pressure applications. They can be used with raised face, male and female, and tongue and groove flanges, and many sizes and styles. ASME B16.20 - Metallic Gaskets for Pipe Flanges: Ring-Joint, Spiral-Wound, and Jacketed
  • Metallic gaskets are made from a combination of materials. These gaskets are used for special applications where a tight fit is needed. Ring joint flanges (RJF) often use these gaskets. ASME B16.20 - Metallic Gaskets for Pipe Flanges: Ring-Joint, Spiral-Wound, and Jacketed

API Gasket Stamping

• Manufacturer
• Manufactured to standard ASME B16.20 or applicable standard.
• Inner ring material stamp other than carbon steel.
• Outer ring material stamp other than carbon steel.
• Nominal pipe size and pressure class.
• Winding material and filler material.

Stamping Location

• Metaillac fillers are color coded on full rim of outer ring.
• Non-metallic fillers are marked with color stripes on the outer ring.
• Inner ring material stamped on inner of outter ring.

Gasket Installation

• Select the right gasket material for the right job.
• Check the flange faces for defects such as scratches, cracks and even corrosion. A damaged flange surface will make it impossible to create a tight seal and could cause a leak or failure when under pressure.
• If a bleed ring, spec blind or other object is to be placed between two flanges, follow the same procedure as above.
• Inspect the gasket to make sure it is in good shape and that it is the right gasket you are suppose to use.
• Make sure the nuts, bolts, studs and washers are clean and have no flaws, if they do replace the ones that do. Lubricate all threads to ensure a smooth tightening.
• Then follow the bolt tightening procedure.

Top of Page