Failure analysis of a steam pipe weld used in power generation plant

In this paper a failure of steam pipe weld after 140,000 h of service in power generation plant has been analyzed. Efforts were made to analyze the cause of failure in both experiment and finite element analysis (FEA) methods. Intergranular cavities and cracks were detected around the primary cracks. Study shows that the main failure mechanism is creep cracking. Cracks developed in this failed pipe as a result of cavity nucleation on grain boundaries, followed by cavity growth and linkage to form micro- and eventually macro-intergranular cracks. This paper brings out the details of investigation and suggests remedial measures to improve performance of this welded pipe under high temperature and pressure condition.