NDTnet 1998 Aug, Vol.3 No.8

Full-Text - Abstract

Heat exchangers are vital components in numerous process plants, and with an increasing focus on operating economy and safety, the benefits achieved from baseline inspection and condition monitoring are evident.

Testing and condition monitoring of heat exchangers is performed using a variety of techniques. Selection of the best suited technique depends on whether the objective is fabrication control, preventive in-service inspection, or inspection due to failure as for example leakage.

This paper will present a range of NDT methods and techniques which can be applied in the examination of tubes in heat exchanger or tubes in other heat transfer or processing equipment

The three often used methods at FORCE Institute for tube examination is Ultrasonic, Eddy Current and Helium Leaktest.

For examination of the individual tubes the eddy current technique and the ultrasonic IRIS (Internal Rotary Inspection system) technique can be applied. Both techniques can for example provide information of the tube wall thickness and if reductions are detected if the reduction is local or general and if the reduction is internal or external. This information can be obtained at the free section of the tube and for the areas below the tube supports.

For examination of the tube ends in the tube sheet area the internal rotating eddy current technique or the IRIS technique can be applied to provide information of the tube wall, for example if cracks or wall thickness reduction is present.

For examination of the tube-to-tubesheet welds FORCE Institute have developed a special scanner based on our ultrasonic equipment the P-scan system. By this equipment the welding-in height can be determined and defects as pores, inclusions and fusion defects can be detected. For detected defects the length and position can be determined.

For detection of leaks in the tube-to-tubesheet welds the helium leaktest technique can be applied. This technique is sensitive to all types of leaks.

Abstract Source:
Book of Abstracts, 7th European Conference on Non-Destructive Testing, 26-29 May 1998, ISBN: 87-986898-0-00

Full-Text Source:
Proceedings of the 7th European Conference on Non-Destructive Testing, 26-29 May 1998, ISBN:

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