Member Stiffness and Bolt Spacing of Bolted Joints


The Rotscher pressure-cone-envelope theory (Rt) is rederived to include bolt clearance as a parameter. Comparison of finite element analysis (fea) and Rt indicates a pressure-cone-envelope half-apex-angle of 20°-25° should be used for bolts in the range of 12-16 mm and for total grip lengths less than 40 mm with recommended bolt clearances. For 12 mm diameter bolts and grip lengths of 160 mm, the Rt pressure-cone-envelope half-apex angle was 27°-28° for recommended clearances. The member stiffness is shown to increase for closer fits and decrease for more free fits according to the theory and fea results. Bolt spacings are discussed based on maintaining material compressive stresses over the contact area between bolts. The bolt spacing depends on the pressure at the parting surfaces, which depends on the thickness ratio of the bolted parts and the total grip length. Application to pressure vessel bolted flanges is discussed. A comparison of Rt and the equivalent cylinder theory as well as one particular example of the equivalent cylinder method, the Association of German Engineers method for calculating member stiffness, is described for grip lengths of 40 mm and 160 mm.

Meeting Name

Winter Annual Meeting of the American Society of Mechanical Engineers


Mechanical and Aerospace Engineering

Keywords and Phrases

Dynamic Response; Finite Element Method; Fits and Tolerances; Flanges; Mathematical Models; Pressure Effects; Structural Members; Theory

Document Type

Article - Conference proceedings

Document Version


File Type





© 1992 American Society of Mechanical Engineers (ASME), All rights reserved.

Publication Date

01 Jan 1992

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