Galvanized pipe making machines is widely used in the production of stainless steel welded pipes for large-scale power station generator sets. Most of the production of stainless steel welded pipes in my country is the introduction or use of advanced foreign equipment and technology.

Heat treatment is an important process to ensure the performance of stainless steel welded pipes. One of its purposes is to eliminate the residual stress generated during the cold working process of coiling the stainless steel strip into a tube and the welding process. The second purpose is to perform solution treatment to make the welded steel pipe The carbides produced at this time are all solid-dissolved into austenite, and then quickly cooled down to prevent the austenite from precipitation or phase change during the cooling process. At present, continuous roller hearth furnaces are generally used in the heat treatment of stainless steel pipes using galvanized pipe making machines in my country. Since no protective atmosphere is used, and producer gas is used as fuel, then pickling is used to remove the heat generated on the surface of the steel pipe after heat treatment. Oxide skin corrodes the steel pipe surface and causes environmental pollution. Some developed countries have now widely used online bright heat treatment technology. Since it can eliminate the traditional off-line heat treatment and pickling process, it has the advantages of increasing productivity and reducing labor intensity. Therefore, my country should vigorously promote the production of stainless steel welded pipes with protective atmosphere control. System development of bright heat treatment technology. The author analyzed some of the problems that occurred during the on-line bright heat treatment of the welded pipe production line introduced in my country, in order to improve the product quality and yield rate.

The factors that affect online bright heat treatment can be divided into six kinds.We introduce the influence of heat treatment furnace sealing and other factors on bright heat treatment.

⑤ The influence of heat treatment furnace sealing

The heat treatment furnace should be closed and isolated from the outside air. Especially where the welded pipe enters the furnace body mouth and the welded pipe exits the furnace body mouth, the sealing rings in these places are particularly prone to wear and should be checked frequently and replaced in time. In order to prevent micro-leakage, the protective gas in the furnace must maintain a certain positive pressure. If it is a hydrogen protective gas, it is generally required to be greater than the standard atmospheric pressure.

⑥The influence of other factors on bright heat treatment

During the working process, the welding must be continuous and stable. When there are holes or seams in the welded pipe, the work of the heat treatment furnace must be stopped, otherwise the welded pipe may be burnt in the furnace. In addition, the welding effect is not good, and the air or moisture sprayed from the welding hole will destroy the protective atmosphere in the furnace and affect the bright heat treatment effect.

Attention should be paid to the adjustment of the power of the heat treatment furnace when the operating speed of the production line changes. When the operating speed of the production line increases, the power of the heat treatment furnace must be increased accordingly to ensure its heating temperature. When the operating speed of the production line decreases, the power of the heat treatment furnace must be reduced first to prevent the welded pipe from being burnt due to excessive heating temperature.

The stainless steel welded pipe adopts the non-oxidation online bright heat treatment technology with shielding gas not only improves the quality of the welded pipe, but also eliminates the traditional off-line heat treatment and pickling process. The treated welded pipe can get the best corrosion resistance and lower strength. And the plasticity is good, which can greatly meet the needs of industrial pipes such as condenser pipes and chemical pipes.

The main factors affecting the on-line bright heat treatment of stainless steel welded pipe made by galvanized pipe making machines are ①The influence of heat treatment temperature. ②The influence of protective gas. ③The influence of cooling temperature. ④The influence of welded pipe surface. ⑤The influence of heat treatment furnace sealing. ⑥The influence of other factors on bright heat treatment.