*Wrong bolt type used for flanged joint connections. Grade #2 bolts have been used thus far.
Use correct studs, washers & nuts.
*Poor pipe alignment prior to bolting flanged fittings together.
Check flange faces for damage. Use taper drift to align bores. Check facing gap with a feeler...
Is this a replacement of the original system? If so, check the original design spex.
Is this a new instalation? If so, check the local fire regulations for spex (if applicable).
Is the environment salt or fresh water? This will give you two options for suitable materials.
If you must use...
