Steel pipe knowledge: characteristics of spiral steel pipe

Spiral steel pipe features: Spiral steel pipe production process is simple, high production efficiency, low cost and rapid development. The strength of the spiral welded pipe is generally higher than that of the straight seam welded pipe. A narrower blank can be used to produce a larger diameter pipe, and a blank having a different diameter can also be produced using a blank of the same width. However, compared with the straight seam pipe of the same length, the length of the weld seam increases by 30 to 100%, and the production speed is low.
In general, the diameter of the tube can be divided into outer diameter, inner diameter, and nominal diameter. The outer diameter of the pipe of the spiral steel pipe is indicated by the letter D, followed by the size and wall thickness of the outer diameter. For example, the seamless pipe with an outer diameter of 108, the wall thickness is 5mm, and is represented by D108*5. The plastic pipe is also With the outer diameter, such as De63, other such as reinforced concrete pipe, cast iron pipe, galvanized pipe, etc., are represented by DN, and the nominal diameter is generally used in the design drawings. The nominal diameter is for convenience of design and manufacture and maintenance. A standard, also known as the nominal diameter, is the specification of the tube (or fitting). The nominal diameter of the pipe is not equal to its inner diameter and outer diameter. For example, a spiral steel pipe with a nominal diameter of 100 MM can be used for several types such as 102*5, 108*5, etc., 108 is the outer diameter of the pipe, and 5 is the wall thickness of the pipe. Therefore, the inner diameter of the steel pipe is (108*5-5)=98MM, but it is not exactly equal to the difference between the outer diameter of the steel pipe and two times the wall thickness. It can also be said that the nominal diameter is close to the inner diameter, but it is not equal to the inner diameter. A pipe diameter specification name, in the design drawings, so use nominal diameter, the purpose is to determine the pipe size, pipe fittings, valves, flanges, gaskets and other structural dimensions and connection size, nominal diameter using the symbol DN If the outer diameter is used in the design drawings, a comparison table of pipe specifications should also be made to indicate the nominal diameter and wall thickness of a certain type of pipe.
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