Roughness of steel pipes

Roughness of steel pipes refers to the machining surface has a smaller spacing and small valley roughness.

Two peaks or troughs which the distance between the two (the pitch) is small (at 1mm or less), it is difficult to distinguish with the naked eye, so it belongs to the micro geometry errors. Smaller the surface roughness, the surface is more smooth. The size of the surface roughness on the performance of mechanical parts have a great impact.

Steel surface roughness Ra is usually expressed.

Pipe surface roughness is mainly manifested in the following aspects:

  1. Surface roughness of the wear parts. The rougher the surface, with the effective contact surface area between the smaller, the greater the pressure, the faster the wear.
  2. the nature of the surface roughness with stability. For clearance fit, the rougher the surface, the more easy to wear, so that the work process gap increases; against interference fit, because the assembly will squeeze micro convex peak level, reducing the actual effective interference, reduce the connection strength.
  3. Surface roughness fatigue strength of parts. The rough parts of the surface of the trough there is a big, they look like sharp as gaps and cracks, the stress concentration is very sensitive, thus affecting the fatigue strength of parts.
  4. Surface roughness of parts corrosion resistance. Rough surface, easy to corrosive gas or liquid through the valley penetrate microscopic surface to the metal inner layer, resulting in surface corrosion.
  5. Surface roughness of the sealing parts. Rough surfaces can tightly fit between the gas or liquid through the gap between the contact surface leakage.
  6. surface roughness of parts contact stiffness. Parts with surface contact stiffness is under external force, the ability to resist deformation of the contact. The stiffness of the machine depends largely on the contact stiffness between the various parts.
  7. affecting the measurement accuracy of parts. Parts measured surface and measuring tools to measure surface roughness will directly affect the measurement accuracy, especially in precision measurement. In addition, the surface roughness of the part plated coating, thermal resistance and contact resistance, and radiation reflectance properties, resistance to the flow of liquids and gases, the flow of current conductor surface and so have different degrees.

Seamless pipe Specification, standard and identification

Seamless pipes are extensively applied for the nuclear device, gas, petrochemical, ship building and boiler industries. Seamless pipes dominates 65% of market share in Chinese boiler industry.