Small-diameter welded steel pipe is a steel pipe made of steel plate or strip steel after crimping and welding. Small-diameter welded pipe has simple production process, high production efficiency, many varieties and specifications, and less equipment investment, but its general strength is lower than that of seamless pipe.

The oxide film on the surface of the hot-rolled seamless pipe is thin and dense, and it is not easy to fall off. Normally, seamless pipes will produce 0.2 ~ 0.3 mm scale in heat treatment equipment. Slab defects in this range can be removed with galvanized iron oxide.

The main difference between cast iron pipes and steel pipes is that they have different uses, different characteristics, and different classifications.

Submerged arc welding is one of the mechanized welding methods with high production efficiency today. Its full name is submerged arc automatic welding, also known as automatic arc welding under flux layer. It is a welding method in which an arc burns under a flux layer.

Welding crack is the most common serious defect in steel pipe welding (such as seamless steel pipe, welded steel pipe). Under the joint action of welding stress and other brittle factors, the bonding force of metal atoms in the local area of the welded joint is destroyed and the gap formed by the new interface is formed.

The detection methods of surface defect detection of a500 rectangular tube include eddy current testing, ray testing, liquid penetrant testing, ultrasonic testing, magnetic particle testing