Mechanical properties (stretch of material)
Mechanical properties tubes as the breaking strength and the yield stress are rather important for determining whether a bending device is capable of bending the pipe.
For the bend itself it is a very important indication, material elongation. Simply put this concerns how much the material can be manipulated (bent) before it is damaged. The stretch of the material is collected by the fundamental tensile tests, must be given in % and the higher the value the better the properties of bend.
(The calculation for determining the required stretch of the tubes)
Material esp. Chemical composition of the tubes also has an impact on the choice of point of view in particular materials themselves instruments (friction, wear, lubrication). For more information on the individual combinations of materials see the chapter dedicated to instruments.
How the tubes are made
The method of manufacture of the tubes determines, not only the accuracy of the tube, but also determines the construction of the tools, the size and shape of welds has a significant effect of the distribution of pressure and the bend. Therefore, if necessary, where possible, place the weld in neutral positions, when the pressure tends to zero and the weld is not affected by pressure or stretch.