Guidelines for the Avoidance of Vibration Induced Fatigue in Process Pipework

MTD Ltd, 1999. — 130 p. — ISBN 1 870553 37 3.In response to the problem of vibration related fatigue in process piping systems, a Joint Industry Project was set up by the Marine Technology Directorate Limited (MTD). The result is this set of Guidelines which are designed to:
provide awareness of the most common vibration excitation and response mechanisms;
provide a qualitative assessment of the likelihood of failure due to vibration;
identify the geometric features that can contribute to fatigue failures of small bore connections;
suggest potential modifications to reduce the likelihood of failure associated with vibration related fatigue;
identify suitable survey and assessment techniques which can be used to evaluate a piping system in its operational environment.
The Guidelines can be used at any time during the design stage from concept to detailed design.
In addition they also apply to existing plants that are undergoing modification or when the process conditions in the plant are being changed.
Although the impetus for the Guidelines has come from the offshore industry, they have been designed to be equally applicable to onshore petrochemical plants and other process industries.
The Guidelines are based on four excitation mechanisms; flow induced turbulence, pulsation, high frequency acoustic excitation and mechanical excitation. However pulsation has not been analysed as part of this project, but limited guidance is given to enable problem areas to be recognised and followed up via references.The Guidelines are divided into four major sections.
The first (Section 2) outlines the different vibration mechanisms and their effect on pipework and small bore connections.
The second (Section 3) is the methodology to assess the likelihood of failure of piping systems and small bore connections for the various excitation mechanisms.
The third (Section 4) outlines possible design solutions or best practices for piping systems or small bore connections that are susceptible to vibration.
The fourth (Section 5) outlines survey methods for vibration measurement and assessment of pipework fatigue in operating plant.
Where the type of excitation or complexity of response is outside the scope of these Guidelines, specialist advice should be sought.