Description
Insulation sets are often used in petrochemical applications electrically isolate two mating flanges to reduce the likelihood of creating a galvanic cell which would result in corrosion of the flanges and pipework. Insulation sets are also used to prevent the flow of electrostatic charge to reduce sparking in hazardous environments.
Insulation sets often comprise an insulating gasket and set of two insulation and two steel washers and one insulating sleeve per bolt.
VCS
The VCS insulation set is designed for Very Critical Service and uses a stainless steel core faced with glass reinforced epoxy (GRE) resin and utilises a spring energised PTFE seal. The high strength resin allows these gaskets to be used in very high pressure applications up to flange ratings of API 20,000. VCS has been designed to be used in both raised face and RTJ groove flanges and also mismatched combinations of the two flange styles.
VCS sets are supplied with GRE insulation washers which have greater compressive strength and resistance to cracking than commonly used materials such as reinforced phenolic resin.
VCFS
The VCFS insulation gasket is a development of the VCS design to make a fire-safe insulation set. The VCFS includes an additional coated metallic seal to retain the internal pressure along with the spring energised PTFE seal used in the VCS. VCFS uses coated metallic insulating washers to maintain compressive strength after being exposed to fire. The development of the high-strength coated steel washers removes the need for the use of an additional insulating washer.
VCFS is fire safe tested to API 6FB.
PGE
The PGE insulation set uses a machined, glass-reinforced epoxy (GRE) resin with an o-ring or spring energised seal. PGE can be used for flange ratings from class 150 to 600 and offers greatly improved compressive strength over conventional insulation sets with greater resistance to overcompression and cracking.
PGE can be constructed from standard G10 or high-temperature G11 resin with a seal ring which can be manufactured from a range of rubbers or PTFE. PGE insulation sets are supplied with GRE sleeves and washers with zinc plated steel backup washers.
PGE gaskets are supplied with GRE insulation washers with a greater compressive strength and resistance to cracking the commonly used materials.
Standard Insulation Sets
Neoprene-faced phenolic resin gaskets are often used in class 150 and 300 applications and for use between -40 and 100°C and often comprise a central gasket and two reinforced phenolic, two steel washers and one Mylar sleeve per bolt. Being an old design Neoprene-face d insulation sets are often only used for low pressure applications with low installation stresses and can manufactured in two styles Type E (full face gasket) and Type F (inside bolt circle gasket).
The insulation washers can be replaced with stronger G10 items with improved compressive strength. The insulating sleeves can also be supplied manufactured from phenolic resin or high-temperature Nomex fibre.
Type D Insulation Sets
Type D insulation gaskets use the same basic materials as the standard insulation sets but are designed for RTJ flanges they are manufactured from reinforced phenolic resin. Type D gaskets have an oval cross-section and are suitable for low pressure service up to ASME Class 600 rating applications.
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