Oil casing pipe is a steel pipe that used to support the oil and gas well wall,to ensure that the drilling process and after the completion of the normal operation of the entire oil well.Each well according to different drilling depth and geological conditions,to use a few layers of casing pipes.After the casing pipe well, it should be used with cement,pipe accounted for more than 70% of all.
Oil casing steel grade：H 40，J 55，K 55，N 80，L 80，C 90，T 95，P 110，Q 125 and so on.The end of the oil casing processing forms:short round thread ,long thread ,buttress thread ,special buckle etc.
Domestic casing requirements
1.domestic casing according to the provision of SY/T6194-96,The length of the casing is not fixed,the range of 8-13m. But not less than 6m of the casing can be provided,the number shall not exceed 20%. of the nominal wall thickness.
2.the casing inside and outside surface shall not have folding,crack,rolling reduction and scarring.These defects should be completely removed,the depth shall not exceed 12.5%. of the nominal wall thickness.
3.except coupling surface without folding,crack,rolling reduction,surface defects.
4.bushing and a connecting hoop thread surface should be smooth,not allowed to burr,tear and enough to make the thread strength and disruption of tight junctions of other defects.