Quasi-Theoretical Method for Calculating the Rigidity of Multi-Pass Tube Plates

Abstract

Tube plates of heat exchangers often consist of circular elastic plates into which tubes are secured by welding or swaging. The holes in the plate into which the tubes are fixed are arranged in zones within the outer boundary of the plate to suit the nesting of the tubes.

Such tube plates are flexed principally by a hydrostatic pressure differential. In this action they function as many-times multiple-connected elastic plates and exact analysis is greatly complicated by the many internal boundaries.

Since such boundaries are normally grouped in the form of zones of regularly arrayed, identical and uniformly pitched holes, the notion of ‘equivalent elastic constants’ as discussed in a related paper, reference (6), can be used to describe the average behaviour of such drilled zones. The number of significant internal boundaries can thus be reduced to the number of zones corresponding with the number of nests of tubes, usually two or four.

The boundaries of the nests usually possess symmetries about the diameters of the plate. Using this fact together with the notion of equivalent elastic constants a method is developed in both detailed and simplified form for predicting theoretically, through an integral equation, the flexural behaviour of characteristic types of tube plate with encastré and simply supported boundaries.

These theoretical methods were tested experimentally on several models whose behaviour was recorded by means of interferometry. Agreement between theory and experiment was established within acceptable limits.