HDPE-EVOH double wall composite pipe is specially manufactured for fuel suction lines and fill lines of underground fuel storage systems at gas stations. Adopting multi-layer co-extrusion technology, the inner pipe is integrated with an EVOH high barrier layer to suppress hydrocarbon permeation and reduce fuel vapor escape. The unique pipe-in-pipe double containment structure provides secondary safety protection. The annular interstitial space between inner medium pipe and outer HDPE protective pipe can connect with leak detection devices for continuous monitoring. Once the inner pipe is damaged, the outer wall can contain leaked fuel to prevent soil and groundwater contamination.
Made of high-density polyethylene material, the composite pipe exhibits excellent chemical compatibility with gasoline, diesel, biodiesel and ethanol-blended fuels. It avoids electrochemical corrosion problems commonly found in traditional buried steel pipelines and achieves long service life under underground conditions. Optional conductive modification can dissipate static charge accumulated by fast-flowing fuel, effectively lowering fire risks in hazardous fueling zones.
Electrofusion welding with matched PE fittings is adopted for pipeline connection. It creates permanent molecular fusion between pipe and fittings, forming reliable sealed joints and cutting potential leakage points. The pipe is available in coiled and straight forms. Coiled pipe reduces on-site welding joints, accelerates laying progress and controls construction cost. With proper backfill, complicated concrete trenches are unnecessary. It works well for new gas station construction and renovation of existing fuel facilities.
The pipe maintains stable mechanical performance under soil pressure and vehicle load. Its burst pressure exceeds normal working pressure greatly to guarantee safe operation. A full set of supporting fittings including elbows, tees, reducers and end caps can be supplied to construct complete underground piping networks. It is widely applied for fuel suction pipelines, fill pipelines and VRU vapor recovery pipelines.
With the EVOH barrier layer, hydrocarbon permeation loss is significantly reduced to meet strict environmental standards. Multiple sizes are available to match different flow requirements and site layouts. Featuring high safety, anti-permeation performance and low maintenance demand, HDPE-EVOH double wall composite pipe provides a stable underground piping solution for fuel suction and fill lines of filling station projects worldwide.