Gasket selection

[Kaadm]

Hello everybody,

A pressure control globe valve made of carbon steel (SCH 160,CS ASTM A106 GRB) has been

severely corroded in a gas plant,this valve is placed in between two pipes (SMLS,ASME B36.10M,

BE END, SCH 160, CS ASTM A106 GRB)assembled by a spiral wound gasket (GSKT SPRL WND ASME

B16.20 ASME B16.5 CL 600,TP304, SS WDG, Graphite Flr,TP 304, SS INR RING,CS OTR RING).

THis valve has been changed by another valve which has the same design only made by Stainless

steel instead of Carbon Steel.

my question is how to connect (gasket type) a pipe made by a Carbon steel with Stsainless

steel valve?

i believe that the gasket mentioned above is not suitable for this assemblage due to the

electrochemical potential caused by contactig the inner ring (SS)to a Pipe flange made by (CS)

any help would be appreciate,

Best regards,

Adem

 

[rustbuster]

What is the process fluid? the cathodic ration shouldn't be an issue as you have a large anode. An insulation kit could be considered if you have concerns.

 

[bmoorthy]

If there is galvanic corrosion concern exists then while dissimilar material are assembled one generally use insulation gaskets (Insulation kit= Gasket, Sleeved fasteners, washers).

These insulation kits are readily available in the market.

Galvanic corrosion issues will generally occur in liquid service (Gas seldom behave as electrolyte).