Carbon Steel Bolts for All Alloys
Carbon Steel Bolts for All Alloys
(OP)
Is carbon steel nuts and bolts with PTFE coat suitable for all alloys suchas SS316, DSS (22% Cr), SDSS (25% Cr), Alloy 825 and Alloy 625?
Our client accepts CS nuts and bolts even without coating for piping flanges and asks for CRA nuts and bolts used for valves.
Also SS316 for non-wetted nuts and bolts are accepted for DSS/SDSS valves. I believe it should be fine as they may not face any issue.
Please comment.
Our client accepts CS nuts and bolts even without coating for piping flanges and asks for CRA nuts and bolts used for valves.
Also SS316 for non-wetted nuts and bolts are accepted for DSS/SDSS valves. I believe it should be fine as they may not face any issue.
Please comment.





RE: Carbon Steel Bolts for All Alloys
The use of type 316 stainless fasteners with duplex stainless steel is not as problematic if they non-wetted as you state.
RE: Carbon Steel Bolts for All Alloys
Since I am working for Oil and Gas Clients and thermal expansion may not be a problem as the operating temperature is generally low (below 70 degC).
Also regarding galvanic corrosion,most of the facilities are in the dessert, do we still expect galvanic corrosion as there may not be moist conditions.
RE: Carbon Steel Bolts for All Alloys
RE: Carbon Steel Bolts for All Alloys
It should also be noted that the client is not alone. Process Industry Practices, Piping Class PIP PN03SD1B01, 2008, for 316L piping also shows bare B7s for fasteners.
Steve Jones
Corrosion Management Consultant
http://www.linkedin.com/pub/8/83b/b04
All answers are personal opinions only and are in no way connected with any employer.
RE: Carbon Steel Bolts for All Alloys
I don't think that his particular question can be answered in a single thread.
There have been many, many questions about nut and bolt selection and applications in these fine engineering forums.
CoryPad states:
Carbon steel fasteners, even with PTFE coating, have problems when used with more passive materials like stainless steels and nickel alloys
Several PTFE (and other)Bolt coating systems are available for a variety of offshore and industrial duties.
http://www.metcoat.com/xylan-coatings.htm
http://www.metcoat.com/assets/files/fk12200hrsaltf...
I have specified and used bolting with XYLAN coatings for decades..... I beg to disagree with that statement
MJCronin
Sr. Process Engineer
RE: Carbon Steel Bolts for All Alloys
RE: Carbon Steel Bolts for All Alloys
RE: Carbon Steel Bolts for All Alloys