... the same,and the purpose is very close. In the oil drilling,K55 API 5CT casing or tubing is a relatively ... grade steel,it is mainly used for shallow oil and gas extraction,especially in natural gas and coal bed methane exploitation. It ... 11960; 7).Approved by ISO9001, SGS,BV 8).Usage:oil pipeline,oil natural gas,industrial gas,water transportation; 9).Flexible payment with L ...