Steel pipe fitting details

Steel pipe fittings, especially tees, elbows, and large and small joints, are becoming more and more commonly used in pipeline construction. This is mainly due to their good forming, strong pressure resistance, and simple welding form, which ensures the bearing capacity of the pipeline. Therefore, in process pipeline engineering, especially in high temperature, high pressure, and flammable and explosive pipelines such as the petrochemical industry, the rational use of steel pipe fittings and the quality of the steel pipe fittings themselves directly play a decisive role. Because of this, in the pipeline design and installation process, especially in the high-temperature, high-pressure flammable, and explosive pipeline projects in the petrochemical industry, no matter from design selection or processing, and manufacturing, to every aspect of construction, installation, and inspection, design, manufacturing and The personnel of the installation unit must strictly check to ensure the quality of its selection, materials, manufacturing, installation and inspection, otherwise it will cause immeasurable losses during the construction and production of the device. During the construction process, we found that the steel pipe fittings arrived Quality mainly exists in the following aspects:

1. Uneven wall thickness of steel pipe fittings: Uneven wall thickness of steel pipe fittings mainly occurs in the parts where the steel pipe fittings have the greatest deformation. For example, the wall thickness of the back of the elbow is thinner than that of other parts; the wall thickness of the pipe mouth and the steel pipe fitting body are different. Relevant national standards stipulate that the maximum wall thickness reduction of steel pipe fittings shall not exceed 1 2 or 5 Å of its nominal thickness. However, actual measurements on site found that some wall thickness reductions reached 20 to 30 Å. For the inspection of such problems, it is often difficult to find them with ordinary calipers and other measuring tools. At this time, it can only be measured using an ultrasonic thickness gauge.

2. Excessive hardness: The problem of excessive hardness is mainly caused by the heat treatment process after forming. The solution is to perform another heat treatment with the correct heat treatment process. This problem can generally be solved

3. Defects caused by materials and processing: Such problems are the most harmful to the safety of the device and are troublesome to inspect. There are many and complex factors that cause defects, including defects in the material itself and defects in processing and manufacturing processes as well as defects caused by incorrect heat treatment processes.