OVERVIEW: The internals of the valve were heavily graphitised and requiring refurbishment with the guide channel for the valve entirely corroded away. A replacement would have taken up to 12 weeks. Chemcote’s refurbishment saved replacement costs and significant delays.
Cast iron Valve body
The internals of the valve were heavily graphitised requiring refurbishment as a replacement would have taken up to 12 weeks because this is an imperial non-standard item. Guide channel for the valve was entirely corroded away. Coating and refurbishment had to be completed within 120 hours to prevent disruption to existing shutdown schedule.
Chemcote recommended RB 300 at 1200μm nominal thickness, a glass-flake filled vinyl ester which provides a tough impermeable barrier that will last in excess of 10 years. Externals finished with top-coat RL 500PF, a moisture and surface tolerant coating.
Protect critical sealing faces
Abrasive blast to remove graphitised metal
Grind rebates on flange faces to allow coating to wrap around preventing crevice corrosion due to misaligned gaskets
Remove graphitised material with air chisel
Hot pressure wash – re-grit blast to AS 1627.4 cleanliness standard with a minimum 75μm profile
Application of 3 coats of RB 300
Install nylon bars to replace corroded guide
Test valve operation
External application of RL 500PF in 2 coats
The valve was refurbished, saving the client replacement costs and waiting time. The client was extremely satisfied with this job and have since awarded other items to be refurbished by Chemcofe using similar methods.