A pipeline system is provided for a pumping system for fluid products, such as gasoline, diesel fuel and chemicals, and including a pump for pumping such products from a storage tank through through the primary pipeline of the pipeline system to a product dispenser. The pipeline system includes a secondary containment system for the primary pipeline between the tank and dispenser which includes telescoping pipe sections of different diameters. The telescoping piping is installed around the primary pipeline and the pipe sections are, prior to final installation, movable between intermediate and final positions, for enabling completion, testing and inspection of the primary pipeline prior to final completion of the secondary containment system. A fusion welding wire bond is provided between overlapping portions of the telescoping pipe sections for bonding these sections in the final positions thereof. An air test clamp assembly enables air pressure testing of the secondary containment system.