Fuel Piping Systems Underground

The primary underground pipe materials are:

• Fiberglass piping – primary and secondary. There are 2 primary providers of fiberglass pipe in the US: Smith Fiberglass and Ameron

• Flexible double wall plastic piping.. Flexible plastic piping has had a mixed history based on failures associated with some of the earlier versions of the products. There are currently 2 primary providers of flexible plastic piping in the US: EBW (Franklin) and OPW (Environ)

• Steel primary piping with a fiberglass or coated steel containment. The primary providers of these piping systems are Perma-Pipe and Rovanco.

The primary benefits of fiberglass underground piping are:

• Proven history of installation and operational success and proven secondary containment systems
• Local qualified installation specialists and local material and parts availability
• Inherent corrosion protection, and internal chemical resistance for fuel additives
• Relative ease of installation and flexibility for a nearly any system configuration.

The benefits of pre-engineered systems are:

• Ability to place multiple primary pipes within a single containment jacket
• Pre-assembly can minimize installation labor
• Welded steel piping provides highest strength pipeline to resist ground and thermal loads
• Lowest costs for long piping runs

The benefits of flexible plastic piping are:

• Ease of installation
• Lack of pipe joints for runs up to 250 feet

Common problems with underground pipe systems

• Workmanship of joints causes re-work after testing
• Damage to piping from excavation or drilling
• Damage to piping during backfill, compaction, and surface paving
• Damage to piping from ground or surface loads or thermal changes
• Thermal expansion / contraction causes leaks at pipe joints and sump fittings
• Leakage at pipe penetrations to tank sumps

Durng installation, piping should be inspected and pressure tested in accordance with the manufacturers requirements prior to backfilling. Typically a local inspection by building or fire officials is required at this point. Underground piping primary and secondary should also be pressure tested after backfilling is complete and prior to th system being placed into service. This helps protect against the problem of damage during backfilling and surface paving.

California regulations will require an enhanced leak detection test for underground fuel piping. The test, performed by a qualified testing service, includes pressurizing the pipe with a tracer gas, and checking the piping run for leakage.

Underground piping systems are inherently difficult to inspect. However since many problems occur where the piping enters tank sumps and building, these areas should be inspected on a regular basis, at least monthly.

Underground piping system, including secondary containment should be pressure tested at least annually. Many State and local regulations require annual testing.

RELATED: 

• Piping Systems – General
• Piping Systems – Aboveground
• Piping Systems – In Buildings