Generalized Tetra-Parametric Assembly Model for the Optimization of Bolt Tightening in Pipe Flanges

Abstract

The elastic interaction phenomenon in flange assemblies has an influence on the preload state of tightened bolts, which causes significant variations in the final load distribution. In such assemblies, steel has traditionally been the material of choice, but there is also a growing trend towards the use of HDPE. Given that HDPE and steel assemblies have varying degrees of stiffness, the elastic interaction is predicted to be greater in those assemblies. This study uses finite element analysis (FEA) to investigate this phenomenon, focusing on the elastic behaviour of HDPE flanges and comparing them with their steel counterparts. Comparative evaluation using the Tetra Parametric Assembly Method (TAM) and the Elastic Interaction Coefficient Method (EICM) underscores the TAM's effectiveness.

This research extends the scope of TAM applications and optimizes tightening procedures for HDPE flanges, thereby enhancing their reliability. The 30-30 rule for tightening emerges as a reliable method for HDPE-to-steel connections. A detailed study of the 8-bolt and 28-bolt models shows that the bending and elastic interactions are complicated and depend on the geometry and material properties. For example, when there is more proportion of HDPE or the geometry is larger, the elastic interaction is stronger. Also, the friction has a negligible impact on the TAM parameters. The TAM effectively optimized the tightening process with variation of bolt force ranging from low of 1% 8% for small model. This validation provides crucial insights for engineers and researchers, facilitating the development of robust HDPE flange designs. It became apparent with larger models that the TAM method falls short in optimizing bolt loads, as it yields variations in maximum bolt force ranging from 1% to 16%.

Date of Award	2 May 2024
Original language	American English
Supervisor	IMAD Barsoum (Supervisor)