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API 5CT casing steel grade classification and introduction

Views:2     Author:Site Editor     Publish Time: 2019-05-21      Origin:Site

What is API 5CT?


API is short for American petroleum institute, 5 refers to the fifth committee, and you can see that these are all standard specifications set by the fifth committee. CT refers to casing tubing.


What is casing:


Well pipe refers to the steel pipe running into an oil well or gas well. There are three basic types of well pipe: drill pipe, casing, and tubing. The oil pipe is used to transport oil and gas to the ground. The casing is used to protect the lining of the well.


Steel grade classification


Divided into four groups:


Group 1: H (40), J (55), K (55), N (80), R (95) steel grades


Group 2: C (95/110), L (80), M (65), T (95) steel grades


Group 3: P (110) steel grade


Group 4: Q (125) steel grade


Chemical composition of material


The API standard only specifies the steel grade, and the chemical composition of the pipe is generally selected by the manufacturer. In the standard, in addition to the maximum content of C, Mn, Mo, Cr and Ni of steel grades l80-9cr, l80-13cr, c90-1, t95-1, C110 and Q125, and the corresponding minimum content of l80-9cr, 13Cr, c90-1, t95-1 and C110, the maximum content of C, Mn and Ni is only stipulated in groups 1, 2 and 4. Steel grades H40, J55, K55, n80-1, N80Q, M65 and P110 do not specify alloying element content.


The same specification of pipe, the production plant selected by the steel is not necessarily the same. However, the impurity elements P and S in all steel grades and API standards have always been stipulated. The sulfur and phosphorus content in group 1 is defined as less than or equal to 0.030%, and the sulfur and phosphorus content is further defined as less than or equal to 0.005% and 0.020% for some steel grades in group 2, group 3 and group 4.


Heat treatment requirement


Materials of J55, K55 and n80-1 should be normalized to full length;


The materials of n80-q, P110 and l80-1 shall be quenched and tempered for full length, and the minimum tempering temperature of l80-1 shall be 566 degrees Celsius.


N80 steel grade includes n80-1 and n80-q, of which n80-1 products shall be normalized, or the manufacturer shall choose to normalize and temper; N80-Q steel grade products for full - length quenching and tempering. In fact, n80-1 and n80-q are mainly represented by different heat treatment methods. Although they are all N80 steel grade products, the abbreviations in the finished products are also different: n80-1 is abbreviated as N1, and n80-q is abbreviated as NQ.


Special material is delivered in hot rolling condition..

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