Which type of butterfly valve connection is best to use underground?

The mechanical joint is considered the best type of connection for a butterfly valve used underground due to its flexibility and ease of installation in confined spaces. Mechanical joints are designed to accommodate slight misalignments and provide a robust seal, which is essential for underground applications where ground movement and settling may occur.

Additionally, mechanical joints allow for easier maintenance and repair. If a valve needs to be replaced or serviced, the mechanical joint can be disassembled without requiring cutting or extensive excavation, making it a practical choice for underground installations where accessibility can be limited. The materials and design of mechanical joints are typically suitable for various soil conditions, contributing to their durability and effectiveness in underground environments.

In contrast, flanged joints generally require more space for installation and maintenance, which can be challenging underground. Welded joints, while providing excellent strength, can complicate repairs as they may require cutting and re-welding. Threaded joints may not be ideal for underground use due to the risk of corrosion and the potential for failure under ground movement or pressure changes. Overall, the mechanical joint’s combination of reliability, flexibility, and ease of maintenance makes it the most suitable choice for underground applications.