Seamless tube high pressure boiler tube rolling process

Seamless tube high pressure boiler tube rolling process

1) Heating of the tube blank
After the tube blank is sawed, it is heated in a gas-fired annular heating furnace with a diameter of 48 meters. The annular furnace is divided into 9 control shorts. The first and second sections are preheating sections, which are heated by the upstream section and high-temperature flue gas; the third, fourth, and fifth sections are heating sections, which undertake all heating tasks. 22 burners; the 6th, 7th, 8th, and 9th pseudo-soaking sections eliminate the temperature difference between the interior and the surface caused by the tube blank passing through the heating section. The heating time is different, and the temperature difference of the end face of the tube blank is controlled within ±10 °C.

2) Piercing and rolling
Pierce with a vertical Discher punch. According to the specifications of the finished pipe, adjust the roller distance, guide plate distance, head extension, feeding angle and rolling angle of the piercing machine, and pierce the capillary of the appropriate size. The pierced capillary is sent to seven mandrel continuous rolling mills with limited movement for rolling, and the rolling table calculated by the mathematical model controls the reduction, continuous rolling speed and mandrel graphite lubrication. The steel pipe exiting the continuous rolling mill enters the sizing machine. According to practical experience and theoretical analysis, the functional relationship between the outer diameter and wall thickness accuracy of 20G pipe and the steel pipe diameter-to-wall ratio, carbon equivalent, void size, total reduction rate and tension coefficient can be found, so that the outer diameter of the finished pipe can be guaranteed. and wall thickness tolerances in accordance with relevant standards.

3) Online detection
The tube rolling line is equipped with high-quality and perfect temperature measurement, length measurement, diameter measurement and thickness measurement system, which can effectively control the process.

4) Magnetic flux leakage inspection
The magnetic flux leakage flaw detector imported from the United States is set up online. The high pot can be tested online one by one. According to the requirements of GNB/T12606-90 "Magnetic Leakage Flaw Detection Method for Steel Pipes and Round Bars" and GB5310-95, a flaw detection sample tube is equipped to remove the excess steel pipes.