HIGH-STRENGTH PIPE FOR OIL WELLS Russian patent published in 2009 - IPC F16L9/02 C21D8/10 C21D9/08 C21D1/28 C22C38/22 

FIELD: oil industry.

SUBSTANCE: invention refers to oil producing industry and particularly to casing pipes and tubing strings meant for being operated in corrosive media containing hydrogen sulfide and carbon dioxide. The pipe is made from chrome-molybdenum steel containing the following, wt %: carbon 0.1-0.35, chrome 1.0-6.0, molybdenum 0.4-1.0, and is subject to normalisation and double tempering. Steel has ultimate resistance σ_u of not less than 690 MPa, yield point σ_y of not less than 570 MPa, relative elongation δ of not less than 20% and impact strength KCV at the temperature of -50°C of not less than 70J/cm².

EFFECT: providing high strength of pipes in combination with cold resistance and resistance to sulfide stress corrosion cracking and to carbon dioxide corrosion.

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