Abstract

The primary design condition in conventional onshore oil and gas pipeline standards is based on limiting the hoop stress under the maximum operating pressure to a fraction of the material specified minimum yield strength. This fraction is referred to as the utilisation factor and is varied as a function of location, temperature and joint type to achieve a level of conservatism consistent with the failure susceptibility and failure impact of the pipeline.

While this methodology has served the industry well for many decades, recent industry trends have created a need to consider other design methods. For example, the current utilisation factors are not necessarily applicable to the high steel grades (X100 and above) being considered for large diameter pipelines. For these grades, the utilisation factor results in thinner pipe walls, and since susceptibility to major failure threats, such as corrosion and equipment impact, is more influenced by wall thickness than hoop stress, lower overall reliability may result.

Author:

Nessim, M.

Publisher:

Pipelines International

Year Published:

2012