What type of connection requires access to facilitate maintenance or repairs?

Concealed slip-joint connections are designed in such a way that they are not immediately visible or easily accessible. Maintenance or repairs to these types of connections require additional effort to expose the joint, which might involve removing drywall, flooring, or other obstructions. This need for access highlights the importance of proper planning in plumbing systems, as connections that are difficult to access can lead to increased labor costs and time during maintenance.

In contrast, threaded connections are relatively easy to access and repair because they typically have exposed threads that allow for easy disassembly. Direct pipe connections can also be more straightforward to maintain, provided they are not concealed. Welded connections, while strong and reliable, can pose similar challenges as concealed slip-joint connections since they require cutting or grinding to access the joint for repairs.