Case Study

Case Study: Wedge Gate Valve Cover and Pedestals



Client

Engineering Industry, UK.

Application Date

March, 2021.

Scope of work

Internal and external corrosion protection of 6″, 10″ and 14″ wedge gate valves, bodies, covers and pedestals. The valve is subject to crude oil at a maximum service temperature of 80°c.

Substrate

Ductile iron.

Products

Internal: Polyglass VEF/ Polyglass VEHA.

External: Plasmet ZF, Corrocoat Zip E, Corrothane AP1 coating system.

 

Coating system

  • Rebated flange faces.
  • Machine surfaces masked up and protected prior to abrasive blasting and coating.
  • Abrasive blasted the internal surfaces with new abrasive in accordance with ISO 8501-1 to Sa2 1/2 surface finish, to achieve a surface profile of 50 microns.
  • WGC body, cover, wedge and yoke: applied Polyglass VEF to wetted surfaces to achieve a minimum DFT (Dry Film Thickness) of 1250 microns.
  • Thickness checked and spark tested at 17kva.
  • Abrasive blasted the specified external surfaces with new abrasive in accordance with ISO 8501-1 to Sa2 surface finish, to achieve a minimum surface profile of 50 microns.
  • Applied coat of Plasmet ZF primer to achieve a minimum DFT of 100 microns.
  • Applied Corrocoat Zip E to achieve a DFT of between 500-700 microns.
  • Applied top coat of Corrothane AP1 – coloue: RAL 1023.

 

Coating credentials

Polyglass VEF: A glass flake vinyl ester acrylic co-polymer, excellent in immersed environments. Excellent flexibility in immersed environments. Excellent flexibility undercutting resistance and sliding abrasion resistance.

Plasmet ZF: A two pack epoxy coating compound incorporating glass flake, ZF has passed standard Norsok testing against system 1 – use on carbon steel, with a max operating temperature of <120 structural steel, equipment exteriors, vessels, pipework  and valves including in tidal and splash zones, and Systems 3B – internal surfaces of carbon steel vessels – ballast water tanks/internal seawater filled compartments.

Corrocoat Zip E: A 2 pack flake epoxy based coating system. It offers durable protection in aggressive atmospheric and immersed environments offering excellent edge coverage.

Corrothane AP1: A polyurethane/acrylic topcoat, a high performance cosmetic topcoat to provide excellent colour retention and weathering properties. Designed for use on marine and offshore structured work in aggressive service environments.

 

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