When periodic disassembly of the valve is not required, the basic type of bonnet used is the?

The basic type of bonnet used when periodic disassembly of the valve is not required is the molded bonnet. This design is typically a solid, one-piece construction that eliminates the need for any joints or fasteners that facilitate disassembly. The molded bonnet helps to enhance the integrity and reliability of the valve since there are no seams where leakage might occur, making it suitable for applications where maintenance is infrequent or unnecessary.

In the context of valve design, this construction method is often used in environments where stability and strength are prioritized over accessibility, leading to greater operational efficiency without the need for regular upkeep. The molded bonnet can effectively withstand pressure and temperature changes, ensuring the valve performs reliably over time.

The other types of bonnets—bolted, welded, and screwed—have been designed to allow for periodic maintenance and inspection. For example, bolted bonnets can be taken apart easily for servicing, while welded bonnets offer a secure, permanent connection but make disassembly challenging. Screwed bonnets provide another method that facilitates easy removal but still allows for maintenance, making these less suitable when disassembly is not part of the operational plan.