SSAW steel pipe
Q235A, Q235B, 0Cr13, 1Cr17, 00Cr19Ni11, 1Cr18Ni9, 0Cr18Ni11Nb
Generally smooth, bright
Export standard packing or according to customers’ requirement
Within10-15 workdays,25-30days when the quantity beyond 1000tons
X70 pipeline site welding technology and quality control points
The X70 pipeline steel is API 5L pipeline steel with a minimum yield strength of 70300psi, or 485 MPa.In fact, in the standard of API 5L, the pipeline steel pipe is divided into two grades, that is, PLS1 steel pipe that only requires strength grade and PSL2 steel pipe that requires more performance parameters. PSL2 steel pipe is required to mark its rolling method, such as thermo-mechanical controlled rolling, marked with M, and Q for quenching.
PSL1 steel tube minimum yield strength minimum tensile strength weld minimum tensile strengthMPa (psi) MPa (psi) MPa (psi)L485 or X70 485 (70300) 570 (82700) 570 (82700) Table 2 performance requirements for PSL2 grade steel tubesThe yield strength and tensile strength of PSL2 steel tube are stronger than the tensile strength of weldMPa (psi) MPa (psi) MPa (psi)L485 or X70 min Max min Max min0.93 570 485 635 570 760(70300) (92100) (82700) (110200) (82700)Note: for pipe diameter 1219, Kv=54J,General D the impact energy requirements of the 1422 mm diameter 27 j, 0 ° C
At present, the X70 pipeline steel tubes are all micro-alloy carbon-manganese steels controlled by ligation. The micro-alloy mainly consists of Nb, V and Ti, and the total content of the micro-alloy does not exceed 0.15%.Therefore, the structure of pipeline is composed of acicular ferrite and bainite, and generally has good welding performance.According to the literature, in order to avoid the occurrence of crack, require a minimum of 100 ° C welding preheating requirements.
2 overview of X70 steel tube wire ring peak welding processSince the large-scale adoption of X70 steel pipe in the west-east natural gas transmission project, a variety of welding process combinations have been tested in the field girth seam welding, mainly including the following two types
(1) cellulose electrode root welding with flux cored wire filling cover technologyThis process is generally used for all the mainline welding except the automatic welding adopted in the western part, which belongs to the semi-automatic welding method.
(2) automatic welding combinationAutomatic welding of roots and other passes by mixed gas shield.Due to the adoption of no liner welding root welding, so there is the use of multiple internal welding machine welding root welding, or the car crawling welding, or Lincoln STT technology welding root welding and other methods.
The Process Flow
Cangzhou Steel Pipe Group (CSPG)Co.,Ltd.
has more than eighteen years history company which located in Lecong Iron and Steel World, a well-known steel distribution center in China, with superior geographical position and convenient water and land transportation.
We are a direct-selling manufacturer specializing in the research and development of spiral steel pipes, steel coiled pipes, anti-corrosion steel pipes inside and outside. Since its inception, the company has been guided by a brand-new thinking of steel pipe product market based on the business philosophy of honesty, pragmatism and knowledge-seeking.
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