VBA APP for the Calculation of Optimal Tightening Sequences for Ring Type Joints

Abstract

For pressure vessels gasketed joints, obtaining a uniform bolt load distribution is mandatory in order to ensure leak-free service of the joint. However, due to the elastic interaction phenomenon, it is difficult to achieve a uniform bolt load distribution. To address this difficulty, standards recommend tightening sequences that have shown good performance. However, these sequences have to be carried out in several passes; in addition, the standards point out that each assembler should develop its particular tightening sequences. In order to overcome these disadvantages, it is possible to find methods that provide a particular tightening sequence with which a uniform bolt load is obtained in a single pass tightening sequence. The most popular method is the Elastic Interaction Coefficients Method (EICM). In previous works [1,2], a new methodology called Tetraparametric Assembly Method (TAM) was developed for ASME Ring Type Joints (RTJ). In comparison with the EICM, the TAM provides very accurate results with much lower cost. In this work, the TAM has been implemented in Microsoft Excel (programmed in Visual Basic for Application), to obtain in a few seconds an optimal tightening sequence for most RTJ (NPS, Class and SCHD) for any target load and any assembly pattern using one or two passes.