Which item allows disassembly of piping joints without causing leaks and is used in maintenance access points?

• A. Drain valves
• B. Mainline isolation valve
• C. Unions
• D. Water supplies

Answer: (C)

Unions are fittings designed to connect two pipes with a removable center section, usually a nut and gasket. This design lets you separate the joint easily for maintenance or replacement without disturbing other joints in the run. When the union is tightened, the gasket or sleeve creates a leak-tight seal, so disassembly and reassembly can be done with minimal risk of leaks. That makes unions ideal at maintenance access points where you need to remove a section of piping, service components, or replace a segment without draining or disrupting the entire system.

Draining valves are for draining sections of pipe, not for permitting clean disconnection of joints. A mainline isolation valve stops flow but doesn’t provide a reusable, leak-tight joint that can be disassembled. Water supplies refer to the source and don’t describe a fitting that facilitates disassembly.