Short answer: fuel piping is tested more often than most owners expect — before backfill, again after backfill and before the system enters service, then on a repeating schedule that includes annual line leak detection, periodic tightness testing every few years, and visual checks of sumps and penetrations between formal tests. The intervals below reflect

Short answer: underground fuel piping falls into three families. Fiberglass systems carry the product inside a fiberglass wall with secondary containment built into the same structure. Flexible double-wall plastic piping — the composite family our own products belong to — pairs a polyethylene primary with an EVOH barrier and an outer jacket, with no rigid

Short answer: the sump is the watertight box under the dispenser where the underground fuel lines turn up into the island. It keeps soil and groundwater out of the transition, gives every fitting a controlled space to live in, and — when it is kept dry and monitored — it is where a small leak

Short answer: the common rule is to test underground fuel piping at 150 percent of its maximum operating pressure, hold that pressure for a set period — thirty minutes is a typical figure — with no measurable drop, and repeat the test after any repair. Double-wall systems add a second test: the interstitial space between