• High-pressure applications: Ensures no leaks even under demanding conditions.
• Safety-critical systems: Eliminates the risk of leakage in sensitive applications.

3. Pressure-sealed: This design uses screws to hold the body and cover together, but the sealing is achieved by a compressible gasket that responds to internal pressure. It provides:

• Balance between maintenance and sealing: Easier disassembly than welded, with good sealing performance.
• Pressure-assisted sealing: Seal improves as internal pressure rises, beneficial for globe valves.

The best choice for application will depend on factors like pressure rating, desired level of maintenance access, and budget：

• Pressure Rating: For high pressures (as specified by the manufacturer), a welded connection is essential for safety and leak prevention. Bolted or pressure-sealed might not be sufficient.
• Maintenance Needs:  bolted connection allows for easier disassembly if frequent maintenance required . For applications with minimal disassembly needs, welded or pressure-sealed is better.
• Budget: Welded connections are generally more expensive due to complex manufacturing and specialized maintenance needs. Bolted connections are most cost-effective. Pressure-sealed falls somewhere in between.
• Specific industries might have regulations regarding valve cover connections. Ensure your choice complies with any relevant standards. Larger valves might benefit from bolted connections for easier handling during maintenance. Consult the manufacturer’s specifications for their recommendations on the appropriate cover connection method based on the valve’s pressure rating and design