(35CrMo alloy steel pipe contains 0.32-0.40 carbon, 0.17-0.37 silicon, 0.40-0.70 manganese, 0.15-0.25 molybdenum and 0.80-1.10 chromium.(2) The main alloying elements in steel are generally expressed in percentages, except for individual microalloying elements. When the average alloy content is less than 1.5%, the steel number is usually marked with element symbols, but not with content. However, in special cases, the number "1" can also be marked after element symbols, such as "12CrMoV" and "12Cr1MoV". The former has a chromium content of 0.4-0.6%, the latter is 0.9-1.2%, and the other components are all the same. When the average content of alloying elements is more than 1.5%, > 2.5%, > 3.5%... When the content is marked after the element symbol, it can be expressed as 2, 3, 4... And so on. For example, 18Cr2Ni4WA. (3) Vanadium, titanium, Ti, Al, B, RE and other alloying elements in steel belong to microalloying elements, although the content is very low, they should be marked in steel grade. For example, in 20MnVB steel. Vanadium is 0.07-0.12% and boron is 0.001-0.005%. (4) High-grade and high-quality steel should be added "A" at the end of steel grade to distinguish it from general high-quality steel. (5) Alloy structural steels for special purposes, with steel numbers crowned (or suffixed) as symbols for the purpose of the steel. For example, 30CrMnSi steel for riveting screw, the steel number is ML30CrMnSi.Alloy pipe and seamless pipe have both relations and differences, so they can not be confused.Alloy pipe is defined by the material used in production (i.e. material), as the name implies, it is made of alloy pipe; seamless pipe is defined by the production process (seamless), which is different from seamless pipe is seamless pipe, including straight welded pipe and spiral pipe.