Reinforcement Structure and Selection of Pressure Vessels

Reinforcement structure

Pressure vessel connection reinforcement usually adopts three reinforcement structures: reinforcement pad, thick walled pipe reinforcement, and integral forging reinforcement, as shown in the following figure.

 

Reinforcement pad

As shown in the above figure (a), the reinforcing pad is welded to the connection between the shell and the connecting pipe, with a simple structure and convenient manufacturing. However, the reinforcing pad cannot fully adhere to the metal of the shell, resulting in poor heat transfer effect. When used above medium temperature, there is a significant thermal expansion difference between the two, which causes significant thermal stress in the local area of the reinforcing pad; In addition, the reinforcing pad is connected to the shell by overlapping, which makes it difficult to form a complete structure with the shell, resulting in poor fatigue resistance. Generally used in normal temperature, static load, medium and low pressure situations. Generally, an M10 threaded hole is required on the reinforcing pad for the passage of compressed air to check the tightness of the weld seam.

 

 

Thick walled pipe reinforcement

Weld a thick walled connecting pipe at the opening, as shown in (b) above. Due to the thickened part of the takeover being within the maximum stress zone, it is more effective in reducing the stress concentration factor than the reinforcing pad. The structure is simple, there are few welds, and the welding quality is easy to inspect, so the reinforcement effect is good. High strength low alloy steel pressure vessels generally adopt this structure due to their high sensitivity to material notches, but it is necessary to ensure full penetration of the weld seam.

 

 

Reinforcement of integral forgings

As shown in the above figure (c), the connecting pipe and part of the shell, along with the reinforcement part, are made into a complete forging, and then welded with the shell and connecting pipe. The reinforcement metal is concentrated in the area with the highest stress in the opening, which can effectively reduce the stress concentration coefficient; Butt welds can be used, and the weld and its heat affected zone can be moved away from the maximum stress point, with good fatigue resistance. But the supply of forgings is difficult, and the manufacturing cost is high. So it is only applied in important pressure vessels.

 

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