5.Casing Coupling: Hebei Borun Steel Trade Co.,Ltd is a manufacturer and exporter with 15 years' experiences.We mainly exports Carbon Steel(Seamless steel pipe,OCTG and so on).If you're interested,pls contact me. Technical standard API SPEC 5CTã??API SPEC 5B Product grade H40ã??J55ã??K55ã??N80-1ã??N80Qã??L80ã??C95ã??T95ã??P110 Specification range OD127~365.12mmï¼?4 1/2"~13 3/8"ï¼? Thread types Short round thread(STC)ã??Long round thread(LC)ã??Buttress thread(BC) Application of product Internally threaded cylinder for joining two lengths of threaded casing pipe Contact Info Email:octgpipes@126.com Whatsapp/Skype:+86 18233500310 Linkedin:Tina Lee