Dril-Quip, Inc.
METHODS FOR DECREASING STRESS IN FLANGE BOLTING

Abstract:

Systems: and methods for decreasing bending stress in flange bolting for a connection between a flange and an adjacent piece of equipment is provided. The flange connection includes a single flange with multiple bolts extending: therethrough. The bolts are threaded into the adjacent piece of equipment at one end, and a nut is disposed at an opposite end. of each bolt to provide a means for tightening and/or securing the flange connection. The equipment to which the flange is attached may include subsea well equipment with relatively large outer diameters. The disclosed flange connection utilizes: an initial region of a counterbored (or unthreaded) hole in the mating equipment piece just prior to the start of the thread formed through the equipment. Additionally, a compound hub flange connection is disclosed to further reduce the bending stress on the bolts.