Bolts and nuts ASME SA193GRB8CL2 and SA194GR8M ?

[Kall545]

Hello
As an European what bolts and nuts does people mean when they talk about these 2(two) ASMEs below ?: (Are they AISI 304(A2-70) or 316(A4-70/80) equivalent ?)

Bolts:
"SA193GRB8CL2"
= ASME SA193GR B8 class 2.

Hexagon nuts:
"SA194GR8M"
= ASME SA194GR 8M.

What "GR" and all those mean ? Is GR=Grade ?
Can I just use common 304(A2) or 316(A4) stainless fasteners ?
+Does these "ASMEs" also determine thread standard ? Are the threads metric or ?

Searching information about these ASMEs just leads to a lot of Chinese and Indian websites.

 

[btrueblood]

SA193 Gr B8 is type 304, class 2 is solution treated and strain hardened to 100 ksi min. yield strength (for 3/4" sizes and under). These can be tougher to find (class 2) than plain B8 grade, but you might get bolts that come close to that strength level in standard roll-threaded forms, if you have them tested by an independent lab. That is what some specialty bolt suppliers do.

GR8M for the nuts is type 316.

You can find regular B8 fasteners (not type 2) on McMaster.com

 

[iangineer]

Yes, GR is the grade.
SA-193 uses UNC thread standards for 1" and below. 8UN for larger than 1" diameter.

I am not familiar with metric information.

 

[XL83NL]

SA-193 uses UNC thread standards for 1" and below. 8UN for larger than 1" diameter.

I am not familiar with metric information.

SA193/A93 references A962 for thread dimension requirements. To the best of my knowledge and experience, A962 also 'allows' a.o. metric thread. See table 2 of A962.
In principle, when specifying A193 ... studs (where ... = B8M or B7 as an example), you specify chemical and mechanical requirements. You can always buy and desire a A193 B7 stud with BSPP threads if you like; the dimensional aspect is often considered loose of the ASTM (material & chemical) aspect.

Huub
- You never get what you expect, you only get what you inspect.

 

[iangineer]

To the best of my knowledge and experience, A962 also 'allows' a.o. metric thread. See table 2 of A962.

OK, so UNC for 1" and below, 8UN for larger than 1" diameter is standard, but A962 also says "unless otherwise specified" so you can request anything. That Table 2 in A962 would have been handy a few days ago when I had to deal with an M24 bolt.

 

[XL83NL]

In general, ASTM specs primarily deal with material requirements (chemical, mechanical, metallurgical, etc.), and not per se so much with dimensional things (besides the obvious tolerances on OD and tw). Not saying ASTM doesn't say anything about geometry, but that's typically handled in standards like B16.9 etc.

Huub
- You never get what you expect, you only get what you inspect.