b8m stud with b8 nut. CL300 bolted connection

[lsone]

I cannot for the life of me remember where to find the given torque value for a B8M stud with B8 nut for a CL300 A182 RF flange, industry standard. .15-.19 lubricant coefficient. I am the Client, however for this plant project, there is only a standard for B7/2H bolted connections. This issue has come up after a Level gauge we had to hydro after a couple welds were completed. We did not want to do closure welds at all for this vessel. The LG manufacturer told us the float had to be removed for the hydro. They gave us a procedure for the hydrotest. All of that is fine. The only issue that came up was this LG shipped with a garlock gasket. We do not accept this as a gasket in the plant. We instead replaced it with a 316 spiral inner ring gasket as per the line class spec.. Now the issue is, the LG manufacturer does not have a torque value for the B8m/B8 bolting for a spiral gasket. Our B7 specs are nothing but industry standard. No fancy lubricants no high values. Simply industry standard, but I know aswell as you guys do, we cannot torque a B8 stud to b7 values. Can I get some assistance on this mysterious chart I am looking for?

thank you!

-Matthew

 

[pennpiper]

Check here

http://www.piping-designer.com/Bolt_Tightening_Procedure

http://www.roymech.co.uk/Useful_Tables/Screws/Preloading.html

prognosis: Lead or Lag

 

[lsone]

The one table is for B7/2H bolt up. There will be a different value for a B8M/B8 bolt up as SS is much softer.

 

[tothepoint]

You need to look at the total bolt load required to seat the SW gasket, and then convert that load into assembly bolt torque. Good luck trying to seat a hard, inner ring SW gasket with low stress B8M bolts. If you must use stainless bolting, you'll likely need to upgrade to B8M Class 2 (strain hardened) bolting in order to generate the assembly bolt load required without yielding your bolts.

 

[lsone]

very valid point. We are considering going to b7, 2h bolt up like the rest of the plant, that is used on stainless flanges aswell. 150ft lbs on a 3" cl300 A182/304 flange.