By the calculation of thick wall tube   prestressed stainless steel welded pipe, extrusion billet in the process of   production of stainless steel internal pressure thick wall pipe wall and thick   wall stainless steel tube under different states of stress, temperature and its   coupling analysis, get the following conclusion:

(1) stainless steel welded pipe extrusion   process of thick wall pipe lined with temperature rising, in accordance with the   extrusion process of extrusion on the inner wall of the lining, close to the   extrusion die at the end of the maximum temperature, up to 631 ℃. And the lining   and outer barrel temperature change is not big.

(2) in the non-working state, stainless   steel welded tube maximum equivalent stress is 243 mpa, thick wall pipe mainly   concentrated on the inner wall of the stainless steel thick wall pipe. In the   condition of preheating, the maximum value of 286 mpa, distribution in the   middle of the inner wall surface area. In working status, the maximum equivalent   stress is 952 mpa, mainly distributed in the lining of the top high temperature   area. Stainless steel thick wall pipe internal stress concentration areas are   mainly distributed in high temperature, the distribution and temperature   distribution are basically the same. With the thermal stress caused by  temperature difference thick wall stainless steel tube had a greater influence   on the internal stress distribution.
Thick wall tube

(3) stainless steel   welded pipe, the radial stress in non-working state, thick wall stainless steel   tube prestressed offered mainly by the external prestressing effect, thick wall   stainless steel pipe diameter to a compressive stress state, with a maximum of   113 mpa, distribution in thick wall stainless steel tube outer wall. In the   warm-up state, its maximum radial pressure of 124 mpa, mainly concentrated in   the upper and lower end surface. In working status, and its maximum radial   pressure of 337 mpa, mainly in the top area of the thick wall pipe stainless   steel.

(4) stainless steel by tangential stress,   thick wall pipe in non-working state, the tangential stress along the radial   direction from the inside out pilot, with a maximum of 250 mpa, are mainly   distributed on the inner wall of the stainless steel thick wall pipe. In the   warm-up state, including stainless steel thick wall tube maximum tangential stress is 301 mpa, mainly concentrated in the middle of the thick wall stainless   steel tube wall area. In working status, including stainless steel thick wall   tube maximum tangential stress is 1110 mpa, mainly in the thick wall stainless   steel tube wall high temperature area.