AbstractAPI 5CT Grade L80 (type 1) production tubulars in non-sour gas wells in East Texas failed after relatively short periods in service. Laboratory analysis of failed tubing and casing from affected wells determined that they failed from environmental cracking initiating in the body on the annulus side of the tubing and casing. Laboratory testing also showed that the failed material met thechemical and mechanical requirements of API 5CT for L80 Grade material and also MR0175/ISO1516 material requirements for carbon and low alloy steels. This paper describes the laboratory investigations and results the downhole environments the materials were exposed to and the influence of material heat treatment and well treatment chemicals believed to have promoted susceptibility to environmental cracking.KeywordsAPI 5CT L80 MR0175 ISO1516 environmental cracking SSC carbon steel tubing casing Bossier gas wells chemical treatment hydraulic fracturing