How to determine the length of studs for equipment flanges
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How should the specific length of the studs used for equipment flanges be determined? What is stated in NB/T47027 seems to offer no clear guidance on this; thank you. . . .
It’s best to do the calculations yourself; the dimensions given for 20592 seem to be only sufficient for basic use, and not precise enough.
Should about 15mm of the thread be exposed after the nut is tightened?
15mm seems a bit much, doesn’t it?
My usual method for calculating the length of bolts is to take the distance required for the connection (the spacing between the outer surfaces of the two flanges), add the thickness of 2 nuts, and then add 3–5 thread pitches on each side; this depends on the specific thread pitch of the bolts used. If the thread pitch is 6 mm, then an additional 6x(3–5)x2 = 48–60 mm needs to be added.
There are no studs specifically designed for pressure vessel flanges with a pitch of 6 mm. My method: thickness of two flanges + height of the concave flange structure (6 mm) + thickness of the gasket + thickness of 2 nuts + 10 mm; the final length is rounded to 5 or 0.