Reducing cracking adjacent shell flange connecting bolts
AssigneeGeneral Electric Company
InventorsRobert Paul Czachor, Michael Leon Barron
Life of this patent
Estimating the term…
Abstract
A flanged joint connection for connecting together by a bolted connection a pair of casing shells having connecting flanges. The connection reduces bearing stress concentrations adjacent fillets provided at the junction of the flange and the casing shell surface. A rectilinear edge portion is provided on a bolt head or a spacer, or both, to avoid point contact of the bolt head or spacer and the flange face or fillet. The rectilinear edge portion includes a convexly-curved surface that faces the fillet. The incidence of cracks between a bolt hole and the fillet, as well as the incidence of circumferential cracks between adjacent bolt holes is significantly reduced.
Claims17
A flanged joint connection comprising:
- a. a pair of first and second abutting end flanges carried by respective ones of a pair of flanged casing sections, the flanges each having a plurality of spaced, aligned openings extending therethrough and a fillet at a junction of the flange and an adjacent surface of the casing section;
- b. a bolt having a bolt head and an externally threaded bolt body extending from the bolt head, wherein the bolt head is in surface contact with a first flange surface that extends transversely relative to a casing surface of a first casing component and wherein the bolt body extends through the aligned openings and outwardly beyond a flange surface that extends transversely relative to a casing surface of a second casing component;
- c. a nut threadedly engaged with the threaded bolt body adjacent the transversely-extending flange surface of the second flange;
- and
- d. a spacer positioned between and in surface contact with each of the nut and the transversely-extending flange surface of the second flange, the spacer having an opening therethrough for receiving the bolt body and including a substantially rectilinear outer edge portion positioned adjacent the flange fillet of the second flange and in substantially tangential relationship with an imaginary circle having its center coincident with the longitudinal axis of the casing sections, for rectilinearly distributing over a greater part of the second flange stresses that are induced in the casing second flange when the nut is tightened against the spacer.
A method for reducing stress-induced cracking adjacent a connecting bolt in a bolted flange connection adjacent a bolt hole in a flange extending transversely from the outer surface of a tubular casing, said method comprising:
- a. providing a spacer having a substantially rectilinear peripheral edge portion;
- b. orienting the spacer so the rectilinear edge portion is adjacent a fillet at a junction of a flange and an outer surface of the tubular casing;
- c. positioning the spacer rectilinear edge portion so it is substantially tangent to an imaginary circle having its center lying on a longitudinally-extending axis within the casing;
- and
- d. tightening a bolt that passes through the spacer to urge the spacer against a flange radial surface to distribute over a greater portion of the flange surface bearing stresses that are induced in the flange surface as a result of tightening the bolt so that the spacer bears against the flange radial surface.
Dependencies are inferred from the claim text.