Abstract: A method of and apparatus for sealing a leak in a pipeline wherein a leak repair clamp is provided for originally sealing the leak. The clamp includes a body forming a cavity between the pipeline and body for receiving sealant and a passageway through the body for injecting sealant in the cavity. A plug is provided for stoppering the sealant passageway after the sealant has been injected and includes a blind passageway extending through a head portion and into a mounting portion to terminate at a plugging wall. In this manner, the addition of more sealant to the cavity is made possible by drilling through or removing the plugging wall of the plug to place the blind passageway in communication with the sealant passageway.