Hot rolled seamless pipe, straight seam welded pipe, cold drawn seamless pipe, precision steel pipe, alloy pipe and other steel pipes have different degrees of curve shape in the longitudinal direction (i.e. length direction) in the production process.
The curve degree of some steel pipes can be visually seen with the naked eye, indicating that the steel pipes are already unqualified products. As long as they are regular steel pipe manufacturers, they are not allowed to leave the factory, Others need special instruments and equipment to measure its straightness. This curve degree is expressed in numbers, which is called steel pipe bending or steel pipe straightness. For the standard of steel pipe straightness, the requirements are not high in the general steel pipe for fluid transportation. The concentricity of the nozzle is mainly required for the fluid seamless pipe to facilitate the connection of the pipe.
However, if the steel pipe is used in processing machinery and equipment, especially rubber rollers, central shafts, etc., the requirements for straightness or bending are high, and this is also a very important index of them. Because it involves a problem of processing quantity. The processing quantity directly affects the production cost. If it can’t be processed, the steel pipe is directly a waste. Therefore, when purchasing seamless steel pipe or straight seam steel pipe, manufacturers like the production of roller equipment pay special attention to the detection of steel pipe straightness.
Generally speaking, there are two kinds of calculation for straightness or bending of steel pipe:
1、 Local curvature of seamless steel pipe or straight seam steel pipe: measure the chord height (mm) at the maximum bending of the steel pipe with a ruler with a length of one meter, which is the value of local curvature of the steel pipe, the unit is mm / m, and the expression method is as follows: 2.5mm/m. This method is also applicable to the end bending of steel pipe.
2、 Total bending degree of the whole length of the steel pipe: use a thin rope to tension from both ends of the pipe, measure the maximum chord height (mm) at the bending of the steel pipe, and then convert it into the percentage of the length (in meters), that is, the total bending degree in the length direction of the steel pipe.
For example, if the length of the steel pipe is 10m and the measured maximum chord height is 30mm, the total length curvature of the pipe shall be 0.03 ÷ 10m × 100%=0.3%
Post time: Jan-20-2022