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Development Trend For Acid-Resistant Pipeline Steel Pipe

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The development of pipeline steel pipe began in the early 1920s, it has a history of nearly a century. Within the scope of the present steel world, the mainstream of pipeline engineering application steel grade A, grade B steel developed to X70 and X80, X90 ~ X120. Inspection standard updated from acidic PH = 5.2-weak acid resistant to strong acidic PH = 2.8 ~ 3.2. On the whole, acid resistant pipeline steel development trend is: high clean smelting control technology, low Mn composition design concept and high-grade, double resistance.
API 5L Pipeline Pipe
1. High clean steel smelting technology
For acid pipeline steel pipe, the lower the content of P and S(harmful element), the better quality. General requirements w (P) is less than 0.015% even less than 0.010%. W (S) not more than 0.005%, in some cases even lowered to 0.002%. In order to achieve high levels of smelting clean.
2. Low Mn component design
Almost all the current high grade acid-resistant pipeline steel pipe X65 and X70 uses ultra low C - low Mn content system, compound with Nb, Ti, Ni, Mo and other elements to ensure strength performance.
Ultra low Mn (w (Mn) of 0.6% or less) in the alloy composition design system is to reduce the MnS inclusions formation, Abate center segregation, thus reduce the risk of pipeline steel acid cracking when using.
Mn is important element of solid solution strengthening, reduce its content must lead to the effect of strength loss. In order to guarantee the strength of the pipeline steel performance, low Mn compound pipeline steel pipe need to add the appropriate Nb, Cr, Ti, etc. Use of Nb refine austenite and expand the recrystallization temperature characteristics, fully refined grain size, at the same time (Ti, Nb) (C, N) precipitation improves strength, ensure the mechanical properties such as steel pipe strength.
3. High grade double resistance characteristics
Gas pipeline steel which are used in conveying high content-H2S  are prone to HTC (Hydrogen-Induced Cracking) and SSCC (sulfide stress corrosion cracking) phenomenon, acid resistance pipeline steel pipe must be resistant to both corrosion and Internal stress.