According to American Petroleum Institute standard APISPEC5CT1988 1st edition, casing steel grades H-40, J-55, K-55, N-80, C-75, L-80, C-90, C-95, P- 110. There are 10 kinds of Q-125. The casing shall be supplied with threads and couplings, or in any of the following pipe end forms: plain end, ro...
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