Disponible en CD en formato PDF

Transcripción del abstract original del autor: Gas pipeline systems incorporate numerous welded small bore connections, which are susceptible to fatigue failure due to vibration excited both through the structure and by pressure fluctuations in the gas. These fatigue failures can result in the release of gas and therefore have significant safety implications. To minimize the probability of such failures occurring, it is essential to have a reliable and rapid means of assessing connections that may be at risk. Methods have been developed based on conventional vibration measurement equipment and most types of fittings can be quickly assessed. Results from field measurements show how simple screening criteria have been developed using established fatigue design methods to identify cases requiring urgent action. Causes of vibration at compressor stations and pressure reduction stations are discussed. In addition, examples of fittings and pipe geometries that are susceptible to failure caused by vibration are identified. A rapid assessment can only provide information about vibration levels that exist at the time of the measurements. There are occasions where this is not adequate as the severity of the vibration amplitude varies in a complex manner with the operating parameters of the process equipment. A thorough understanding of the relationship between these characteristics is therefore a key element of a comprehensive fatigue assessment, and equipment has been specially developed to perform long term, continuous monitoring of vibration at multiple sensor locations for this purpose. This equipment can be set up to log trends and capture detailed information and example results are presented with the aim of identifying appropriate solutions for the avoidance of fatigue failures.