Stainless steel bolts & nuts compatibility to avoid galling

[yahoo123]

If I specify ASTM A193 Grade B8M bolts with A194 Grade 8M nuts, will this cause galling (cold welding) since they are made of the same material? However, from my research it seems that the stainless steel nuts and bolts are always specified as a matching pair (identical material). Why is this?

Does anybody know of a nuts and bolts compatibility chart? For example, which A193 bolt should go with which A194 nut or which F593 bolt should go with which F594 nut?

 

[reidh]

To answer your first question, I have not always seen SS nuts and bolts specified as a matching pair. If galling is a concern, which it very well may be if you are threading stainless into stainless, your best bet is the use of an anti-seize type compound on the threads.

To answer your second question, I do not know of any nut/bolt compatibility table that would meet your needs.

-Reidh

 

[yahoo123]

If the pair selected is not of the same stainless steel material, will that induce galvanic corrosion?

 

[CoryPad]

Galvanic corrosion usually wouldn't be the concern. Thermal expansion would be one concern (different rates for austenitic vs. ferritic), as would just overall corrosion performance (why should one part be good while the other is poor).

Regards,

Cory

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.