Pipeline surface roughness is a processing surface with small spacing and small irregularity of valley. The distance between two peaks or two valleys is very small (less than 1 mm), which is difficult to distinguish with the naked eye, so it belongs to the geometric error of microstructure. The bigger the surface roughness is, the smoother the surface is. Surface roughness has a great influence on the performance of mechanical parts.


The surface roughness of pipeline mainly includes the following aspects:
1) Wear resistance of parts with surface roughness. The rougher the surface is, the smaller the effective contact area between the matching surfaces is, the greater the pressure is, and the faster the wear is.
2) Complexity stability of pipe surface roughness. For clearance fit, the rougher the surface, the easier the wear, so as to increase the clearance in the operation process; interference fit, because assembly will extrude the micro-convex peak level, reduce the actual effective interference, reduce the coupling strength.
3) Fatigue strength of parts with surface roughness of pipes. Groove surface roughness is very large, they are like sharp corners, gap and crack, very sensitive to stress concentration, thus affecting the fatigue strength of parts.
4) Corrosion resistance of pipe surface roughness components. Rough surface, easy to make corrosive gas or liquid infiltrate into the surface of micro-metal inner valley, resulting in surface erosion.
5) Surface roughness of pipeline with sealing parts. Through rough surfaces between contact surfaces, gas or liquid leakage clearances can not be closely matched.
6) Stiffness and surface roughness of contact parts. The contact stiffness of partially bonded surfaces is deformed by external force and contact resistance.  The rigidity of the machine depends to a large extent on the contact stiffness between the components.
7) Influencing the measurement accuracy of parts. Some measuring surfaces and measuring tools to measure surface roughness will directly affect the accuracy of measurement, especially in precision measurement. In addition, the surface roughness, thermal conductivity and contact resistance, reflectivity and radiation properties, flow resistance of liquid and gas, and current flow on the surface of conductor all have different effects.