Paint on the threaded bolt holes of studding outlets (pad nozzles)

[jtseng123]

Dear all,

I have a new CS vessel with several pad nozzles. Vendor painted the threaded bolt holes with primer, mid and top coats. I am afraid it can cause issue when installing stud bolt to connect to external valve at site. Shall I ask vendor to strip the paint and apply rust preventative grease ? or leave it alone ?

 

[r6155]

See SA-193 and SA-194
3.2 Coatings—Coatings are prohibited unless specified by
the purchaser (See Supplementary Requirements S13 and S14).
When coated fasteners are ordered the purchaser should take
special care to ensure that Appendix X2 is thoroughly understood.


X2. COATINGS AND APPLICATION LIMITS
X2.1 Use of coated fasteners at temperatures above approximately
one-half the melting point (Fahrenheit or Celsius) of the
coating is not recommended unless consideration is given to
the potential for liquid and solid metal embrittlement, or both.
The melting point of elemental zinc is approximately 780 °F
[415 °C]. Therefore, application of zinc coated fasteners should
be limited to temperatures less than 390 °F [210 °C]. The
melting point of cadmium is approximately 600 °F [320 °C].
Therefore, application of cadmium coated fasteners should be
limited to temperatures less than 300 °F [160 °C].

Regards

 

[jtseng123]

r6155, my issue is painting on the threaded bolt hole, not the bolt itself. Thanks.

 

[r6155]

Please, read again my post.
Threaded bolt hole is the same as a nut. I mentioned SA-193 and SA-194.

Regards

 

[jtseng123]

r6155, that makes sense to treat bolt hole as nut. However, this is just a very typical paint on vessel, not plating or galvanizing.

 

[EdStainless]

No Zn or other low melting point metals in the primer or paint?
I am accustomed to seeing people avoid tapped holes, but when there are some they are not painted and coated with a rust preventive oil (a real RP product and just what ever was around).

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P.E. Metallurgy, consulting work welcomed

 

[r6155]

What does the purchase order say?
It is a good practice to do a surface protection of stud and nuts. There are several types of protections, …teflon, etc. Consult with the Vendor. You decide
Avoid remove studs after installed.

Regards