In my past experience using ASME flanges I was always using small flanges (generally 2" or smaller) and usually of pressure classes anywhere from 600# to 2500#. These flanges always had 4-bolt patterns and occasionally a slightly larger flange would have 8 bolts. I am now working with much larger flanges (but much smaller pressure ranges - 150#) and have noticed there are many more bolts - enough to fill the entire circumference.
Is the reason for this simply that a larger pipe OD = larger area = larger applied force by the internal pressure and therefore more bolts required to ensure proper flange tightness? Is there any more to it? Are these bolt patterns governed by the ASME code or have they just become industry "best practices" over the years?
Thanks
Is the reason for this simply that a larger pipe OD = larger area = larger applied force by the internal pressure and therefore more bolts required to ensure proper flange tightness? Is there any more to it? Are these bolt patterns governed by the ASME code or have they just become industry "best practices" over the years?
Thanks
