In my experience i would say belleville washers are more smoke than substance. Any flexible load considerations are nominal, however I always see them in spec and iso drawings.
I have worked on a substantial amount of LNG, Compressor Station Builds, Pipeline projects, etc.
ASME-PCC-1 is a very nice read.
Feel Free to bounce thoughts off on me email HYTORCMD at GMAIL dot com
In regards to flange assembly I recommend use of a through hardened washer to control...
Are you using ASME recommended parallel joint closure or are you welding the flanges?
Ever thought of using ASME reaction washers to make job hands free, and eliminate bolt side loading?
What diameter pipe are you responsible for? Is there a gasket involved? Do the pipes rely on bolted connections, or do they rely on welds? are the pipes subsea? If bolts, what diameters do you see?
Coatings, and materials are a concern as well as assembly, however there are many solutions...
