Metal-to-metal full face taper-hub flanges: Finite element model evaluation and preliminary plastic analysis results

Abstract

The stress analysis of the flange problem is found to be sensitive to the way in which the component is modelled, particularly so when a finite element program is used to analyse the flange and bolt contact faces. The validity of a number of these finite element models are examined, by comparing the predicted maximum axial bending stress at the intersection of the taper-hub and the cylindrical vessel, with those measured on a large taper hub flange. It is found that a well-thought-through simple model can produce accurate results. In this type of flange it is considered that the magnitude of this stress is critical since, if the bending stress at this intersection reaches yield and subsequently a plastic hinge develops, then undue rotation of the flange could cause leakage. Using an appropriate finite element model, the development of plasticity is studied, from which it is shown that the use of a cylindrical shell yield surface provides a more realistic approach than the simple beam criterion which is unconservative despite its wide use in the existing pressure vessel standards.

Keywords

finite element analysis pressure vessels plant design pipelines structural integrity

Get full access to this article

View all access options for this article.

References

BS 5500: 1997 Unfired Fusion Welded Pressure Vessels, 1997 (British Standards Institution, London).

ASME Boiler and Pressure Vessel Code, Section VIII, Division 1, 1995 (American Society of Mechanical Engineers, New York).

Thomson

Flange design. In Pressure Vessel Design (Eds Spence

Tooth

A. S.

), 1994, Ch. 11, pp. 419–453 (E - FN Spon, London).

Murray

N. W.

Stuart

D. G.

Behaviour of large taper hub flanges. In Pressure Vessel Research Towards Better Design, 1961, pp. 133–145 (Institution of Mechanical Engineers, London).

ANSYS Finite Element Program Manual (Ansys Inc., Houston, Pennsylvania).

Webjörn

An alternative bolted joint for pipework. Design Note, Proc. Instn Mech. Engrs, Part E, Journal of Process Mechanical Engineering, 1989, 203 (E2), 135–138.

Webjörn

Discussion contribution to reference [6]. Proc. Instn Mech. Engrs, Part E, Journal of Process Mechanical Engineering, 1990, 204, 139–140.

Webjörn

Discussion contribution to reference [6]. Proc. Instn Mech. Engrs, Part E, Journal of Process Mechanical Engineering, 1991, 205, 59–62.

Gill

S. S.

The Stress Analysis of Pressure Vessels and Pressure Vessel Components, 1970 (Pergamon, Oxford).