Flange Misalignment torque value 1

[IanMiller]

In the pipeline industry it is not uncommon to experience massive flange misalignments when trying to install a new gasket. I have been asked to write a proceedure for proper installation and torquing of flanges in our system, but I don't know how to adress these misalignment issues. Stating Flange alignment should be limited to 1mm on the Diameter as per ASME PCC-1-2000 would have to proceedure tossed on the trash heep. How would you adjust the torque values for a misaligned flange? What if you have to torgues all the bolts to 1/2 of their final value just to get the flanges to meet. Recently we have has some costly failures of flexatalic gaskets, that is what prompted the new proceedure.

Tanks
Ian

 

[hydrodude]

How about using 4 bolts to get the flange aligned and square then install and torque the rest to 1/2 final value leaving those 4 out of the sequence then remove the first 4 and replace with new ones in case of over stress then do your final torque steps on all bolts. I have always found the main reason for gasket failure is improperly squaring the flange before starting to tighten the bolts. As I always tell the hands, you aint gonna bend that thick hunk of iron to get it closed it has to be square first. Tom