FAILURE ANALYSIS

A major part of our business activity is the review of design failures that present as operating failures in the field. Although many design issues can lead to a piping system failure, there are three main causes:

  1. Poor original design: Design conditions, whether unknown, unexpected or overlooked, were not properly considered — or they were considered but were not adequately planned for. Often, piping systems are not correctly supported and restrained to properly distribute and control thermal displacements and to minimize sags. Piping stresses not predicted by calculations thus occur because the system does not cycle between its original, installed location and an operating, or displaced, position. Instead, as it is cycled, these stresses tend to migrate to new locations depending upon friction loads and temperature gradients. Also, unexpected flow-induced dynamics can occur and, if long unsupported spans exist, they can easily become excited and cause cumulative fatigue damage.
  2. New design conditions: The original design conditions of the system have been changed and the new temperatures, pressures, or flowrates were only considered as process changes and were not reviewed for mechanical considerations.
  3. The piping system or equipment needs more consideration than standard piping codes provide: Codes such as the ASME B31.1, ASME B31.3, ASME Section VIII, Division 1 code, and numerous others have considerations for many situations, but there are times when additional calculations, beyond the official requirements, are needed. Good examples include tube sheets with temperature differentials greater than approximately 200F, nozzle-to-shell connections that do not fall within WRC 107 curves, and flat heads with non-circular openings.

Our years of experience allow us to quickly suggest which item above is most likely responsible for the failure, then we can use the most appropriate techniques and programs to identify the specific problem and recommend an efficient solution.

For more information call +1 (225) 292 9709