Which method is typically NOT used for bonnet attachment?

The method of bonnet attachment that is typically not used is the snapped method. In mechanical and piping systems, a bonnet serves as a cover or protective enclosure for valves and other equipment. Typical methods of attaching bonnets include flanged, union, and threaded connections.

Flanged attachments utilize a flat surface with holes for bolts, providing a strong and secure connection that allows for easy disassembly when maintenance is needed. Union connections add flexibility, as they allow for the quick disconnection of the bonnet without unscrewing or dismantling other parts, making it easier to perform repairs. Threaded connections involve screwing the bonnet onto the body or valve, also allowing for secure and tight fittings.

The snapped method, on the other hand, is not recognized as a standard or reliable method in these applications. This technique usually implies a mechanical snap-fit which may not provide the necessary pressure tightness and security that standard methods like flanged, union, or threaded connections do. Each of those methods is designed to withstand internal pressure, prevent leaks, and facilitate serviceability, which a snapped connection generally cannot guarantee, especially in high-pressure scenarios encountered in power engineering systems.