Which stages in pressure vessel manufacturing are most prone to errors?

1. Welding Stage

High proportion of manual welding: Manual welding leads to poor weld consistency, with rework rates reaching 5%-8%.

Difficulty in controlling process parameters: Fluctuations in parameters such as current and voltage easily cause defects such as porosity and slag inclusions.

Impact of thermal deformation: Thick plate welding is prone to shrinkage deformation, requiring stress relief through heat treatment.

2. Material Cutting Stage

Dimensional error control: Measuring only the diagonal can easily result in parallelogram-shaped body plates, causing weld misalignment.

Low material utilization: Traditional cutting methods easily generate waste, requiring computer-aided material arrangement.

High dependence on equipment: Without a leveling machine, uncoiling and cutting errors can reach over 3mm.

3. Forming Stage

Flame cutting deformation: Shrinkage at the cylinder section ends leads to assembly difficulties and reduced head diameter.

Insufficient mold compensation: Failure to consider material springback results in final dimensions exceeding tolerances.

Instability deformation: Large openings weaken the stability of the shell, requiring temporary reinforcement.

4. Inspection Process

Non-destructive Testing Blind Spots: Tiny cracks may go undetected, requiring the use of multiple testing methods.

Pressure Testing Risks: Overpressure testing may trigger defect propagation, necessitating strict control of the pressure increase rate.

Key Preventive Measures

1. Welding: Employ narrow-gap submerged arc welding to reduce weld deposition, in conjunction with a laser tracking system.

2. Blanking: Simultaneously measure diagonals and side lengths, incorporating a leveling machine.

3. Forming: Use symmetrical cutting, allowing for shrinkage compensation.

4. Inspection: Implement a "three-inspection system" (self-inspection, mutual inspection, and specialized inspection).