Flange Bolt and Nut Material Selection

[denniskb]

Can someone advise where I will find recommendations on the correct bolt and nut materials for ASME B16.5 flanges?

Dennis Kirk Engineering

http://www.ozemail.com.au/~denniskb

 

[rconner]

I think ANSI B16.5 (I could not lay my hands on a recent copy of ANSI B16.5 to know for sure exactly what it now says specifically about bolting materials) has traditionally said that the bolts must be "steel" and also provided sort of a smorgasbord "Group" of ASTM standard numbers that may be acceptable (maybe even with tables indicating some properties of those groups for the engineer to match with demands of specific applications?)

I guess it could thus depend on the specific application and governing code for that application; however, e.g. I know that AWWA C207, Steel Pipe Flanges for Waterworks Service (that refers to B16.5 for basic compatitibility, of at least drilling and other dimensions etc. of some class designs) says,

"Bolts shall be carbon steel, ASTM A307 grade B for class B & D flanges. Bolts for class E and F flanges shall be ASTM A193 grade B7. Nuts shall be ASTM A194 grade 2H. Bolts shall have regular unfinished square or hexagonal
heads, and nuts shall have regular square or hexagonal dimensions, all in accordance with ANSI B18.2.1 for wrench head bolts and nuts and wrench openings."

I think ASTM A307 and A193 are included in the ANSI B16.5 "Group" of acceptable bolting material standards I remembered per B16.5.

 

[codeeng]

As pointed out by rconner B16.5 lists "acceptable" bolting materials, however it does not provide a selection guide based on service or flange material. PV Design Manual by Moss is one of many references available which provides this data.

 

[mk3223]

You could refer to the specific codes, such as AWWA, ASME B31.1, B31.3, B31.4, etc. for the selection based on allowable stress and temperature limit for the material.

Then, you may choose the material in the same category (high/medium/low strength) based on the availability and cost. Also, you could simplify your selection to one or two types, so it won't cause any confusion or mistake during construction.