Seamless steel pipes are widely used in our daily lives, with a particularly important application being as energy transport channels for oil, natural gas, and other energy sources. They can be laid not only on land but also on the seabed, greatly facilitating the flow of energy between regions and offering a transportation method unmatched by land and sea transport.
In today’s society, protecting the security of energy transport channels is becoming increasingly important. The damage to a pipeline abroad has had a significant impact on people, not only increasing their living costs but also seriously impacting regional security. What is so special about oil transport steel pipes, such a vital means of production? Let’s learn more about seamless steel pipes and oil casing. Seamless steel pipe oil casing is the lifeline that keeps oil wells operating. It is primarily used to support the wellbore walls of oil and gas wells, ensuring the proper functioning of the entire well during drilling and after completion.
Oilfield steel pipe and casing differ from ordinary seamless steel pipe. Due to their use in complex geological environments and varying geological conditions, they experience complex downhole stresses, with the combined effects of tension, compression, bending, and torsion acting on the steel pipe body. This places high demands on the quality of the casing itself. In the API SPEC 5CT standard for oil pipelines, the steel grade of oilfield casing and steel pipe indicates its yield strength and other special characteristics. Steel grades are typically designated with one letter and two or three numbers, such as N80.
In most cases, the yield strength of the pipe increases with the letter’s alphabetical order. For example, the yield strength of N80 steel is greater than that of J55. The numerical designation indicates the minimum yield strength of the pipe expressed in thousands of pounds per square inch. For example, the minimum yield strength of N80 steel is 80,000 lb/in². The API SPEC 5CT standard lists casing steel grades as follows: H40, J55, K55, N80, M65, L80, C90, C95, T59, P110, and Q125; and casing steel grades as follows: H40, J55, N80, L80, C90, T59, and P110.
Each oil well requires several layers of casing, depending on the drilling depth and geological conditions. Once lowered into the well, casing is cemented. Unlike oil, steel pipe, and drill pipe, casing is not reusable and is a disposable material. Damage to the casing can lead to reduced production or even the abandonment of the entire well. Consequently, casing consumption accounts for over 70% of all oil well pipes.
Post time: Sep-03-2025