Sour Service. Electroless Ni Plating (Coating)

[bmoorthy]

On most situations Control valve manufacturer does Electroless Ni Plating on the cage/Plug/Seats for various reasons other than corrosion prevention.

The reasons sited are
1) superior Errosion resistance
2) Prevents Galling
3) Finish the helps to control pressure drops
4) Trade Secret reasons
5) Just for standardization, does not want supply taylor made valves, but to pick the valves for the available standard and sell.


Someone (User- Client engineer!!) observed that ENP are no good in sour application, even if it for non corrosion prevention issues, as this will corrode away in no time and the item will become useless (the very objective ENP and paying for that gets defeated)

On the other hand, Control Valve manufacturer swear that they are hearing this situation for the first time.

Question 1
NACE MR 0175/ISO 15156 does not prohibit ENP, EFC 16, EFC 17 also does not impose any special restrictions of ENP, is there any basis for objection for ENP?

Question 2
Are there standards for ENP (like ASTM/API/AWS/ISO) etc

Question 3

Is there any valve specific NACE or is there a need/thinking on those lines?

 

[SJones]

1.
The basis for objection will be what the end user wants, or does not want in this case. Having said that, specifiers may wish to consult NACE Technical Committee Report 6A287 before they specify by hearsay!

2.
There are several standards for ENP: ASTM B733, ISO 4527 for starters.

3.
Why should there be a 'valve specific NACE'? Valves are made from materials and ISO 15156 addresses metallic materials.

Steve Jones
Materials & Corrosion Engineer

http://www.pdo.co.om/pdoweb/

 

[gr2vessels]

bmoorty,
The NACE 0175 does object to any coating, lining, plating and CRA cladding/overlay, in the sense of requesting the base material to be NACE compliant and cladding to not be considered substitute to the base metal corrosion resistance.
cheers,
gr2vessels