Stainless Bolt Codes

[wizard]

I have two sets of M8 stainless steel bolts. One set is coded ' VIBO A2.70' and the other 'VIBO A4.70' Is there any difference in performance or strength etc between the two. I am going to use whichever is recommended by you for chain plates. Thanks in anticipation

 

[Strathglass]

A4 is 316 stainless, A2 is not.

Iain

 

[paulrossall]

A4 is a better standard of stainless and is the only one which should be used below the waterline. I normally only use A4 but I might use A2 inside the boat where it was not likely to be immersed in water (would not use in bilges). Rather than have two types I find it easier just to have A4 in my toolbox.

 

[martinb]

A2 is 304 stainless and A4 is 316 stainless. Both have very similar mechanical properties but A4 (316) has better corrosion resistance, so use the A4

Martin