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Common knowledge oil casing
Feb 18, 2019

A thin tube in which the tubing is inside a reservoir casing.It is the passageway for oil and gas to rise to the surface wellhead, the upper end is connected with the tree, and the output is controlled by the nozzle to the surface gathering tubing manifold.

The oil pipe of low pressure oil layer sits on the wellhead of the ground, and the oil sucker rod and the piston pump inside the oil pipe are connected to the pumping unit, and the oil flow is pumped to the ground through the oil pipe. In fact, the oil pump is composed of a piston pull rod pump, and the oil pump is sent to the surface gathering pipe sump (or storage tank).[1]

Tubing: pipe used to convey oil.

Tubing for oil Wells refers to seamless tubing for oil Wells.The manufacturing method is the same as that of seamless tubes. DZ(geological)35 ~ DZ55 steel is used in China.The steel pipe is threaded at both ends for joint connection.In order to ensure the sealing of the joint, the precision of the thread is strictly required.

  1. Use

Tubing is used for oil well discharge tubing.


According to SY/ t6194-96 oil pipelines and their joints, domestic oil pipelines are divided into unthickened oil pipelines and thickened oil pipelines at both ends.

3. Specifications and appearance quality

(1) as per SY/ t6194-96, the normal length (indefinite length) is 6, 6.5, 7.5, 8.5 and 9.5m.

(2) diameters of pipes and their joints without thickening at the end: 1/2in, 2in, 2/2in, 3in, 3/2in and 4in.

(3) the diameters of the thickened steel tubes at both ends and their joints shall be 1in, 1/4in, 1/2in, 2in, 2/2in, 3in, 3/2in and 4in.

(4) appearance quality according to the standards of the inner and outer surface of the steel tube shall not be folded, rolled, cracks, separation, hairline, scar and deep straight defects.The above defects on the surface of the steel tube can be removed by filing, grinding wheel or other methods. The clearance depth shall not exceed 12.5% of the nominal wall thickness.Defects shall not be soldered or otherwise filled.

4. Chemical composition test

(1) the steel tube and its joints shall be of the same size and shall be made from steel no. DZ35, DZ40, DZ50 or DZ55.The content of sulfur and phosphorus shall not exceed 0.045%, and the content of arsenic shall not exceed 0.15%.Sampling according to gb222-84;Chemical analysis is carried out according to the relevant part of GB223.

(2) American petroleum institute standard apispec5ct1, 1988 stipulates that chemical analysis and determination shall be conducted in accordance with the latest version of ASTME350.

5. Physical performance test

(1) conduct tensile test in accordance with gb228-87.Water pressure test according to the steel and steel pipe diameter, there are clear requirements.There are strict requirements for the thread gauge of tubing according to the diameter of steel pipe.

(2) American petroleum institute standard apispec5ct1, 1988, stipulates that tubing shall be tensile tested;Flattening test;Hydrostatic test;Sulfide stress corrosion cracking test;Determination of grain size (according to astme-112 latest version);Lateral impact test (according to the latest version of astm 370, astm 23);Hardness test (according to ASTME18 standard method for rockwell hardness test of metallic materials).

6. Major import and export situations

(1) the main importing countries of the pipeline are Japan, Argentina, Switzerland, and Spain also have a small amount of imports.Import criteria refer to American petroleum institute (API) standards.API5A(j-55.n-80) is generally adopted;5 ak (P - 105);5 ac (C - 75);5 aj - 55 nue.Specifications: 60.3 * 4.83mm * r-2;88.9 * 6.45 mm * R - 2;73 * 5.51 mm * R - 2.

(2) American petroleum institute standard apispec5 ct1, 1988.There are 7 steel grades: h-40;J - 55;N - 80;C - 75;L - 80.C - 90;P - 105.Tubing ends shall be threaded and coupling or supplied in one of the following forms: flat end;Thread end without collar;Integral connection;Special end machining;Sealing ring structure.

7. Packing

Tubing and fittings, regardless of packing (in bundles, in cases or in bulk), shall be threaded with protection rings to protect the threads of the tubing and fittings.

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