Types of welds for pressure steel pipe

Types of welds for pressure steel pipe is divided into:

A type of weld: 

1.longitudinal joint of steel pipe wall; open pipe in the factory (refers to the steel pipe not buried in concrete, the same below) ring seam, make the joint close the ring seam; 

2.the butt joint of the reinforcing plate at the branching point of the pipe, the joint weld of the butt joint and the corner joint where the reinforcing plate meets the pipe wall; 

3.the joint weld between the bulkhead and the pipe wall.

The second type of weld: 

1.steel pipe wall ring seam; 

2.person hole neck pipe butt weld, manhole neck pipe and the top cover and pipe wall continuous weld; 

3.support ring butt weld and main force fillet weld.

Non-destructive testing of one type and two types of welds is generally based on ultrasonic flaw detection, and X-rays are used as supplementary sampling.

Note 
1. Any one of the above methods can be used. When a type of weld is used for ultrasonic testing, it must be re-inspected by ray. The length of re-inspection is 10% for high-strength steel and 5% for the rest.
2. The second type of weld has a suspicious waveform only in the ultrasonic flaw detection, which cannot be accurately judged, and the radiation is retested.

3. High-strength steel refers to quenched and tempered steel with yield strength ≥450MPa and tensile strength ≥580MPa.

Method	Grade	Low carbon steel or low alloy steel		High strength steel
	Types of weld	First type	Second type	First type	Second type
One	Radiographic inspection rate (%)	25	10	40	20
Two	Ultrasonic flaw detection rate (%)	100	50	100	100
	Radiographic inspection rate (%)	5	Depending on the circumstances	10	5