Which patch option is used when a pipe is fully isolated?

• A. Temporary patch
• B. Installed drainage
• C. Welded patch
• D. Slip patch

Answer: (B)

When you fully isolate a pipe, the main concern becomes removing any residual liquid from the isolated section so the patch can be applied cleanly and stay secure. An installed drainage patch is designed to provide a drainage path for that trapped fluid, letting the segment drain and dry before the patch is set. This reduces hydrostatic pressure and moisture that could weaken the seal, making it the best choice in this situation.

The other options don’t address drainage. A temporary patch is meant for a quick, temporary seal while you continue work. A welded patch provides a permanent repair but requires welding access and a dry, pressure-free environment, which isn’t always feasible in an isolated line. A slip patch can be quick and useful in some scenarios, but it still doesn’t give you a built-in drainage path, which is the key need when the pipe is fully isolated.