Novel minimally-disruptive mitigation methods for pipework vibration issues
Vibration of pipework on pipeline facilities can be a major risk to integrity, in some situations leading to fatigue failure of welded connections, and ultimately a loss of containment, with significant consequences for operations and business performance. There are numerous examples on assets in service where modification would be costly and unnecessary. There is therefore a requirement for mitigation methods which can be easily implemented on existing pipework, and do not require the plant to be shut down and vented. Building on DNV GL’s experience with solutions for pipeline repairs and hot tap interventions, novel methods have been developed which meet these requirements, and have been shown to provide continued long term performance. The first of these solutions is aimed at providing a means for addressing vibration on small bore connections on pipeline facilities, which are often identified as being at risk of fatigue failure. This is particularly of interest where other modification methods might be considered inappropriate, for example where the plant which could not be readily isolated. A test programme has been carried out to quantify the effectiveness of this solution in reducing the vibration of at-risk connections. Knowledge of the improvement which may be achieved has then allowed this to become an approved mitigation measure. Testing was also performed to investigate the simulated performance of the technique over extended service periods. Subsequently, a solution has been developed for tackling high frequency vibration on pipework downstream of compression plant, where high frequency pulsations have the potential to result in fatigue failure. Theoretical modelling has been performed to define the key design parameters, with laboratory testing demonstrating the experimental performance. The solutions presented therefore offer benefits to plant operators by addressing identified pipework vibration risks with minimal disruption to operations.