Experimental Investigation on Rubber-Expanded Tube-to-Tubesheet Joints of Zr Heat Exchangers Available to Purchase

Mechanics of flexible expansion was expounded, and technology points of uniform rubber expanding in tube-to-tubesheet joints of Zirconium (Zr) heat exchangers were introduced. A series of pull-out strength and tightness experiments were performed for rubber-expanded tube-to-tubesheet joints. The experimental results show that the pull-out strength decreases linearly with increasing of operating temperature in the range of 20∼300°C, the pull-out strength of joints composed of Zr tubes attached to 16MnR and 316L tubesheets (abbreviated as Zr/16MnR and Zr/316L joints and heat exchangers include these joints are called Zr heat exchangers) drops much faster than that of joints composed of Titanium (Ti) tubes attached to 16MnR tubesheets (abbreviated as Ti/16MnR joints), and the joint strength can meet the requirements specified in Chinese code & standard at the experimental conditions. It is also found that the tightness of rubber expanded tube-to-tubesheet joints drops obviously with the increase of working temperature from 20 to 200°C, and the sealing performance of the joints enhances markedly when rubber-expanded tube-to-tubesheet joints are subsequently expanded with roller. Moreover, the influences of Enlargement Rate of Tubesheet Hole (ERTH) on the strength of rubber-expanded tube-to-tubesheet joints is discussed, it is observed that the pull-out strength of the connection joints with non-grooved tubesheet holes increases linearly with increasing of ERTH when the expanding pressure is not larger than 38 MPa, whereas this is not the case for the joint with grooved tubesheet holes.