Tube plugging is probably the most frequently used maintenance and repair technique for the tube side of an exchanger. This article provides information on how to locate the positions of tube failures and discusses why it is important to know such information. It describes how to find out where the tubes failed and explains how to analyze what caused failures, seen from the tube side. Descriptions of several kinds of plugs and their uses and plugging techniques are included. Preparation of a plug map, a key to tubeside maintenance, is also discussed.
Although tube ferruling and sleeving are less common, some of the requirements for these maintenance techniques are so similar to those for plugging that this article includes them.
Locating Tube Failures
Tube failures may occur any time in the life of an exchanger. To get the longest, most-effective exchanger service life you must find out where and why the tubes failed. Two techniques that contribute to the failure analysis are 1) establishing the pattern of the failures and their locations along the length of the tube, and 2) extracting the failed tube for chemical analysis and metallurgical examination.
Maintenance workers are usually under pressure to return a shutdown unit to service…