PP pipe processing and common defects


Plates and pipes are the main raw materials for the man […]

Plates and pipes are the main raw materials for the manufacture of special equipment such as boilers, pressure vessels, pressure pipes, etc., to ensure their safe operation. Ultrasound testing is generally required.

Pipe processing and common defects

There are many types of pp pipes. According to different methods, they can be divided into seamless steel pipes and welded pipes; Can be divided into metal bamboo and non-metallic tubes; according to the pipe diameter. The common defects that can be divided into small diameter pipes and large diameter pipe joints are related to the processing methods.

The seamless steel pipe is obtained by the perforation method and the high-speed extrusion method. The perforation method is perforated by a punching machine, and is simultaneously rolled by a roll, and finally sizing and forming by a mandrel rolling mill. The high-speed extrusion method is squeezing. Direct extrusion molding in the press, the pipe size processed by this method is high in precision, and the previous defects in the seamless steel pipe are cracked, folded, layered and mixed. For thick-walled large-diameter pipes, steel ingots can also be processed by forging and rolling. The common defects of forging pipes are similar to forgings, generally cracks, white spots and heavy leather.

The welded pipe is firstly rolled into a tubular shape and then welded by electric resistance welding or submerged arc welding. Generally, large-diameter PP is processed by this method. The mountain has been tested on the plate, so the common defects in the welded pipe are weld defects, which are generally cracks, pores, slag inclusions, and incomplete penetration.

From the viewpoint of ultrasonication, a pipe having an outer diameter of more than 100 mm is generally referred to as a large diameter pipe, and an outer diameter of less than 100 mm is referred to as a small diameter pipe. 2的金属管为厚厚管管。 The metal pipe is not more than 0. 2, the metal pipe is called a thin-walled pipe, and the metal pipe is greater than 0.2 is called a thick-walled pipe. The distinction between a thin-walled tube and a thick-walled tube is distinguished by whether the refracting transverse wave can reach the inner wall of the tube.

The purpose of ultrasonic testing of pipes is to find various defects in the manufacturing process of pipes. pp pipes avoid the use of pipes with dangerous defects. The defects that may exist in the pipes in service (such as fatigue cracks) can also be tested by sample. Quality control. The defects in the pipe are mostly parallel to the axis of the pipe. Therefore, the pipe is detected by a transverse wave that is scanned circumferentially along the outer circle of the pipe.

Detection is dominant. Defects perpendicular to the axis of the tube may also be present in the seamless tube, so oblique incidence detection should also be performed along the axial direction if necessary. For some PPH pipe materials, longitudinal wave vertical human shot detection is also required.