Flange Isolation Products by
Pipeline Seal and Insulator Inc. (PSI)

Flange Isolation products manufactured by PSI include a complete line of Sealing and Isolating Gaskets, along with a variety of Isolation Sleeves and Washers. PSI Flange Isolation products are designed to provide complete electrical insulation of a flange assembly installed in the most severe conditions (internal and external).

PSI products may be delivered individually or as part of a Flange Isolation Kit. All components are certified ISO 9001 with extensive quality control procedures.

Flange Isolation Kits are available for all flange sizes, types, pressure ratings and materials.

A Single Washer Set includes the following items for each bolt:

  • one ⅛” thick steel washer
  • one isolating washer
  • one isolating sleeve

Application Considerations: In buried applications single-washer configurations may be used to allow the Cathodic Protection current to reach the nuts and bolts. If desired, nuts on the opposite side of the cathodically protected flange may be included as part of the Cathodic Protection System.

Double Washer Set includes the following items for each bolt:

  • two ⅛” thick steel washers
  • two isolating washers
  • one full length isolating sleeve

Application Considerations: Double washer configurations may be used for added protection against the possibility of “shorting out” the nuts and bolts. In addition, double washer sets electrically isolate the nuts and bolts from both flanges.

A One-Piece Sleeve and Washer Set includes the following items for each bolt:

  • two ⅛” thick steel washers
  • one one-piece isolating sleeve

Application Considerations: One-piece sleeves are easier to install and allow the inspector a visual indication of sleeve usage. Due to the relatively low compressive strength of this material, its use is not recommended for high pressure or large diameter flanges that require high torque loads. G-10 one-piece sleeve and washer assembly is available for additional strength and convenience.

Flange Isolation Kits by Central Plastics

Flange Isolation Gaskets and Isolation Kits as manufactured by Central Plastics Company are used throughout the world and in numerous Cathodic Protection Industry applications. Flange Isolation Kits have a proven track record for being one of the most effective and reliable products for controlling and maintaining the integrity of piping and tank systems under demanding conditions.

Gaskets are available for delivery individually or in kits. The material a gasket consists of includes Nitrile-Face, Plain Phenolic, G10 and Durlon.

Type E – Full Face Gasket completely covers the flange face from the flange bed to the outside diameter. A Full Face Gasket is used on flat-faced flanges; however, it can be used with a raised flat-face flange to prevent debris from building up in raised areas, thus causing a short.
Type F – Ring Gasket is designed to set inside the bolt circle and is commonly used with raised face flanges.
Type D – Ring Type Joint (RTJ) is an oval phenolic gasket designed to work specifically with RTJ grooved flanges. The RTJ gaskets are sized by R-number.
Type D – BX Gasket is an octagonal-shaped phenolic gasket designed to work specifically with a BX grooved flange. BX gaskets are machined from phenolic tubing and withstand pressures up to 15,000 PSI.

“Jock” O – Ring Type Gasket is either a Full Face (Type E) or Ring Gasket ( Type F) configuration. The “Jock” has a high energy O-Ring elastomer seal that compresses and expands to fill any voids as the flange is tightened; the completely encapsulated sealing element prevents a gasket blow-out. The O-Ring provides a positive, constant seal with zero environmental leakage. Complete contact of flange and retainer prevents fire failure and reduces exposure of the seal to service fluids and the environment. The “Jock” O-Ring gasket is available in Nitrile or Viton seal material.

Isolation Sleeves are designed to be easily inserted in the bolt hole, leaving ample room for the bolt, even when the bolt holes are misaligned. The wall thickness is 1⁄32” (0.79 mm) and can be provided for bolt sizes from ½” (12.7 mm) to 3 ½” (88.9 mm). The material a sleeve consists of Mylar, High Density Polyethylene, Minlon or/and Nomex.

Standard Isolation Washers are manufactured from CE Phenolic, whereas other Washer materials include Steel, G3, G7 or G10. They are available as a single washer and sleeve kit, a one-piece washer kit, a double washer kit or a one-piece double washer kit (Minlon). The maximum operating temperature of a Phenolic Washer is approximately 225° F (107° C), with a compression strength of 36,400 PSI and a dielectric strength of 300 VPM. The G3 and G7 high temperature Isolation Washer has a maximum operating temperature of 450° F (232° C).

Molded One-Piece Sleeve & Washer contributes to reduced handling (many loose parts) and make-up problems in the field. A one-piece sleeve and washer is generally used for one-side flange insulation, however, it can be cut to size for two-side insulation. A Minlon material is used because of its high compression strength and superior toughness.