No permit shall be required in the case of any repair work as follows: the stopping of leaks in drains, soil, waste or vent pipe; provided, however, that should any trap, drainpipe, soil waste or vent pipe be or become defective and it becomes necessary to remove and replace the same with new material in any part or parts, the same shall be considered as such new work and a permit shall be procured and inspection made as hereinbefore provided. No permit shall be required for the cleaning of stoppages or the repairing of leaks in pipes, valves or fixtures, when such repairs do not involve or require the replacement or rearrangement of valves, pipes or fixtures.
(1991 Code, § 8.28)