What is the procedure for bolting conflat flanges before and after baking?
Answer The recommended sequence depends on the flange diameter. But basically, you always tighten opposing bolts (at 180°). You start by choosing a bolt as bolt #1 in direction 1 Bolt #2 is in direction 2 at 180° to direction 1 Bolt #3 is in direction 3, one bolt position clockwise from direction 1 Bolt #4 is in direction 4, one bolt position clockwise from direction 2 Etc Finger tighten all bolts first and then do a small amount of turn (1/8?) on each bolt until compression if sufficient or you have reached the appropriate torque for that bolt size (80 – 100 in. lb. for 1/4″ bolts, 120 – 150 in. lb for 5/16″ bolts) Follow-up Question Do I retighten after 400°C bake? If it is not required and I do it anyway, does it cause any problems? Follow-up Answer First a word of advice about flanges and baking. I strongly recommend that you get Ag plated bolts or some high temperature MoS2 goop to lubricate the bolts. Baking plain stainless nuts and bolts to 400°C gives a high probability of seiz
