The lifetime of SAWH steel pipe has relationship with decarburization, if the surface decarburize, surface strength and wear resistance will reduce the direct impact on the life of daily use. In the heat treatment process, it should be to try not to let the inner and outer walls and exposed to the air. The resulting medium spiral steel surface decarburization is mainly oxygen, water vapor and an oxidizing gas such as carbon dioxide, when the surfaces of the coil and the heated gas contacts the coil will cause oxidation and decarburization, therefore, the control of carbon dioxide in the furnace and the proportion of carbon monoxide is very important. In fact, the spiral steel forging furnace protective atmosphere of nitrogen was added is very effective, some of the nitrogen oxide gas can be dispersed to reduce the spiral steel decarburization.
In order to extend the lifetime of spiral steel pipe, so the main direction of spiral welded pipe are:
(1) the production of large diameter thick-walled tube in order to improve the ability to withstand increased pressure capacity mainly spiral welded pipe;
(2) the development of new kinds of steel, smelting technology to improve the level of production and good quality spiral welded pipe welding, widely used to control rolling and rolling after the heat treatment process, in order to continuously improve the toughness and weldability of the pipe body;
(3) to develop coated pipes, such as the inner wall of the tube coated with anti-corrosion layer, not only extend life and improve the smoothness of the inner wall, reducing fluid friction, reducing the volume of wax and dirt, reducing the number of pigging, reduce maintenance costs.
(4) the design and production of new steel structures, such as the double spiral welded pipe, that is half the thickness of the wall into a double welded steel pipe, not only the intensity is higher than the same thickness of the single tube, and will not appear brittle failure. When using spiral welded pipe to follow certain standards for the production and processing technology, strict control of the production process, it has good quality and performance, play an important role in the use and promotion. Development of space spiral welded pipe is huge, the development of different industries and fields and promotion, effectively reducing the hassle of construction and building, to realize their full value.
