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.

Comparative study of the behaviour of conventional gasketed and compact non-gasketed flanged pipe joints under bolt up and operating conditions

“…Previous work by Spence et al [13] and Nash et al [14], showed the viability of a 2D axisymmetric model, for what is essentially a 3D component. In neglecting the holes in the flange and the presence of individual bolts round the flange, the system can be considered as a continuous bolt ring located at the bolt centre and running round the circumference of the bolt circle.…”

Effect of Bolt Scatter on Different Sizes of Gasketed Bolted Flange Joints: A Comparative F.E. Study

“…Previous work by Spence et al [18] and Nash et al [19], showed the viability of a twodimensional axi-symmetric model, for what is essentially a three-dimensional component. In neglecting the holes in the flange and the presence of individual bolts round the flange, the system can be considered as a continuous bolt ring located at the bolt centre and running round the circumference of the bolt circle.…”

Comparative thermal stress analysis of gasketed and non-gasketed flange joints for safe operating conditions

“…For the first section, an elastic material is used that is valid until the yield stress and the gradient of this section is the Young's modulus of elasticity. The second section functions beyond the yield stress, and the gradient (plastic modulus) is 10 per cent [15] of the Young's modulus of elasticity. Flange joints of 4 in nominal bore of 900# class are used.…”

“…In previous work by [3,4,8,11,15] only 2D finiteelement (FE) modelling is performed. In the present work, a detailed 3D parametric FE model is used as it eliminates the need for simplifications, such as removing effects associated with the bolt hole.…”