Research of Elastomeric Expansion for Tube-to-Tubesheet Joint

Just as hydraulic expansion, elastomeric expansion is an alternative method to produce tube-to-tubesheet joint with low residual stress level. However, the key parameters of the elastomer expansion are different from the hydraulic expansion. For elastomeric expansion, the problems lie in three aspects, (1) the expanding pressure (the radial pressure) applied to the surface of the tube is difficult to be measured directly; (2) the expanding length, which is decided by the final length of elastomer, is less than the original length of elastomer; (3) though grooving on the surface of the tubesheet hole can improve the strength of tube-to-tubesheet joint, the effect is depending on the location and width and number of the grooves. Therefore, in this paper, relationship of the axial pressure and the radial pressure, together with the relationship between the expanding length and original elastomer length and the width of groove, is investigated. It is discovered that the radial pressure is nearly equal to the axial pressure, so the radial pressure can be estimated by the axial pressure. Two equations are derived through this work. One can be used to obtain the suitable original length of elastomer, and the other is for calculating the width of groove.