Meaning of ANSI B... part numbers (ex:B1831BH080050N) 1

[NicV11]

Hi everyone!

I'm currently in search of suppliers for fasteners in military and aerospace field and I've come across some odd and hard to find part numbers. For some of them, I simply can't find anything (such as the one in the title).

So, if I can't find the original part, then I want to have at least the equivalent. The problem is : I don't know if these numbers are significative or not. What I've figured out is that the 4 numbers after the first B represent the fastener's type. As an example, B1831 is used for socket head cap screw.

Now I don't have any ideas what the letters after this numbers are for (maybe surface treatment?).

The next two digits are the metric size of the threads. As an example, in this number, the threading is M8X1.25. Finally, the 2 or 3 digits before the last N are used for the nominal length of the screw, so this one is 50mm long.

So I'm almost sure its a SHCS M8X1.25X50, but I don't know anything about its surface treatment, if its fully or partially threaded and which steel property class it is.

So if any of you have come across this kind of P/N and knows whats what, your help would be really appreciated!

Thanks

 

[atlarson]

The part number code above is defined in ASME/ANSI B18.3.1M. You are correct that this is a M8 x 50 long socket head cap screw. The "B" in the part number specifies that it made of alloy steel, class 12.9, with zinc coating per ASTM B633, FeZn5, type II. The "H" stands for hexagon socket, and the "N" at the end indicatates that it has no special features such as a drilled head or self-locking threads.