LINE PIPE&OCTG

Pipeline: It refers to the transportation of oil, gas, or water extracted from the ground to oil and gas industrial enterprises through pipeline. Pipeline pipes include seamless and welded pipes, with flat ends, threaded ends, and socket ends; The connection methods include end welding, coupling connection, socket connection, etc.

In recent years, 50% of the major oil and gas exploration discoveries globally have come from the ocean, mainly in deep water areas. Global deepwater oil and gas exploration is mainly concentrated in the Gulf of Mexico, Brazil on both sides of the South Atlantic, and the coastal areas of West Africa, which account for about 84% of the world's current deepwater oil and gas drilling activities; Among them, the Gulf of Mexico is the largest (accounting for 32%), followed by Brazil (accounting for 30%), and the third is West Africa. As of now, the total proven reserves of oil and gas in major deepwater areas in the world are 2.060 3 ×  1010M3。 According to Douglas Westwood, a British company, 44% of the world's oil geological reserves in the future will come from deep water areas.

The pipelines used in offshore oil fields can be divided into: OCTG pipelines for subsea oil and gas wells, long-distance transmission pipelines, and internal connection pipelines for offshore oil and gas fields (including subsea gathering and transportation pipelines, risers, and working connection pipelines). OCTG is a seamless steel pipe used for oil and gas well drilling; The amount of pipes used for long-distance transportation pipelines accounts for approximately 40% of the total amount of submarine pipeline pipelines; The internal connecting pipes of offshore oil and gas fields refer to the gathering and transportation pipelines, injection medium pipelines, and connecting short pipes from each wellhead to the gathering point in the oil and gas field. The connection between the seabed and offshore facilities is a vertical pipe, which mainly uses seamless steel pipes. The steel grade and wall thickness of the vertical pipe are a series higher than those of the gathering and transportation pipeline.

Due to the influence of installation, laying, and service environment, deep-sea pipeline pipes have characteristics such as high strength, high toughness, weldability, corrosion resistance, and resistance to large deformation. They have higher requirements for dimensional accuracy, surface quality, measurement and inspection methods, and product traceability. Regarding the characteristics of high strength, high toughness, weldability, corrosion resistance, and large deformation resistance of deep-sea pipeline pipes, China began to develop and research high-performance subsea pipelines in 2005. Currently, Tianjin Yuantai Derun Steel Pipe Manufacturing Group has developed X65 and X70 marine steel. By controlling the production processes of steelmaking, rolling, and heat treatment, its strength, toughness, weldability, corrosion resistance, and large deformation resistance can all meet the requirements of deep-sea, And successfully used in the deep sea.

Comparing the API Spec 5L-2012 Pipeline Steel Pipe Specification, DNV-OS-F101-2013 Subsea Pipeline System Specification from Det Norske Veritas, DEP 31.40.20.35-Gen Shell Pipeline Pipe Specification, GS EP PLR 201 Total Pipeline Specification, and customer requirements in deep-sea pipeline projects such as the South China Sea Liwan Project and the Brazil Petrobras deep-sea project, it was found that the deep processing requirements for deep-sea pipeline pipes are generally higher than those for general pipeline pipes, Mainly manifested in the following aspects.

(1) In terms of geometric dimensions, there are higher requirements for accuracy such as outer diameter, ovality, and wall thickness, while there are strict requirements for pipe end accuracy and length deviation. The comparison of geometric dimension accuracy requirements between ordinary pipeline pipes and deep-sea pipeline pipes is shown in Table 2. The required inner diameter deviation of steel pipes for some deep-sea pipeline projects is shown in Table 3.

(2) The maximum test pressure for the hydrostatic test of deep-sea pipeline pipes needs to reach 200 MPa. The comparison of the hydrostatic test pressure requirements between ordinary pipeline pipes and deep-sea pipeline pipes is shown in Table 4.

(3) The number of inspection projects has increased, and both the finished pipe body and pipe end require ultrasonic testing UT and wet magnetic particle testing ST, with a coverage rate of UT testing reaching 100%; After groove processing, fluorescent wet magnetic particle inspection shall be carried out on the pipe end and groove within 250mm; The requirements for the qualification of flaw detection personnel are higher. The comparison of flaw detection requirements between ordinary pipeline pipes and deep-sea pipeline pipes is shown in Table 5.

(4) The requirements for surface defects are also stricter, and there should be no cracks, cracks, or scratches. The depth of surface defects should not exceed 5% of the nominal wall thickness; The actual wall thickness after grinding shall not be less than the minimum wall thickness.

(5) Increase traceability management. In the production process of deep-sea pipeline pipes, it is necessary to collect more production and quality information, and achieve tracking of production information one by one, including water pressure, flaw detection, geometric dimensions (length, inner and outer diameter of pipe ends, wall thickness of pipe ends, etc.), size distribution, and other information. This requires each steel pipe to be marked with a different code from the time it enters the production line. The marking should be clear and not easily damaged, and hanging tags should not be used. It should be clear and intact from production to use. In addition, establish an information system to upgrade from batch management to each steel pipe management. Record the furnace number, steel grade, heat treatment process, geometric dimensions, flaw detection, and water pressure information of each steel pipe in the system file, which can be checked at any time during the production process.

The product is positioned as high-strength seamless steel pipes for deep-sea pipeline pipes and marine engineering structures, with an annual output of 50000 tons; The product specifications are Ф 114.3～323.9 mm × 4.0～45.0 mm × 6 000~14 600 mm, steel grades are X42~X70, X42N~X60N, X42Q~X100Q. The raw steel pipe should be pre finished steel pipe or heat treated steel pipe that has passed the inspection after straightening and non-destructive testing; The length of the pipe material is a single length; The steel pipe has no defects, and the physical and chemical inspection results show that the performance of the raw steel pipe is qualified; The bending degree of the raw steel pipe is ≤ 1 mm/1000 mm, the outer diameter deviation is (-0.3%~+0.3%) D, and the wall thickness deviation is (-3.5%~+6.5%) t.

(1) The equipment configuration is complete, with high equipment capacity and accuracy. In contrast, many domestic factories do not have automatic inner and outer diameter measurement equipment in their production lines, and the pressure of the hydraulic press cannot meet the requirements. They cannot achieve groove printing, track information one by one, and there are also many limitations in pipe end sizing machines and flaw detection equipment. Meanwhile, due to the large amount of equipment, it has also brought some challenges to our finances. However, the persistent Yuan Tai people, these are not problems.

(2) The inspection process is strict, the product manufacturing time is shortened, the occupied space is reduced, and the transportation is reduced. During the lifting and transportation of steel pipes, more attention is paid to protecting the surface and ends of the steel pipes, which can upgrade or qualify the product quality.