1 March 1997
interior and fittings are also available for gravity sewers but has limited use due to its low impact
j. High Density Polyethylene (HDPE). PE is divided into 3 classifications - low, medium, and
high density. HDPE pipe is more widely used for pressure, gravity, and sliplining applications
than the other PE pipes because it is more abrasion and impact resistant.
(1) Pressure pipe. Standard HDPE pipe, up to 600 mm (24-inch) in diameter is available
and is generally used for pressure pipe.
(2) Large diameter profile wall sewer pipe. Profile wall HDPE pipe is manufactured for
gravity sewers in diameters of 450 to 3,000 mm (18 to 120 inches). Joints can be heat fused or
bell and spigot (with a gasket or thermal weld). Mechanical joints shall be used only where other
methods are unfeasible.
k. Fiberglass. Fiberglass pipe provides a good alternative for use in large diameter force
internal/external corrosion and to high temperature wastes, are important properties of fiberglass
pipe. Design, trench and backfilling procedures, and installation of fiberglass pipes will follow the
manufacturer's recommendations. Specifications shall require that a certified field representative
of the manufacturer be present during installation and to inspect all joints. The following types of
fiberglass pipe may be used:
(1) Reinforced thermosetting resin pipe (RTRP). RTRP pipe may be installed in diameters
of 200 mm (8-inch) through 3,600 mm (144-inch). Jointing systems for RTRP pipe include bell
and spigot, flanged, or special mechanical type couplings. Elastomeric gaskets are used to
provide flexible joints.
(2) Reinforced plastic mortar pipe (RPMP). RPMP pipe is composed of a siliceous sand
aggregate reinforced with glass fibers, and embedded in a thermosetting polyester resin. RPMP
pipe is ideally suited for large diameter applications, and performs extremely well in resisting pipe
wall deflection and internal/external corrosion. The unique fiberglass/resin construction provides
optimum protection against attack from wide range of chemically aggressive environments
including hydrogen sulfide and other sewer gases, most natural soils, salt and brackish water,
and galvanic or electrolytic reactions. No special coatings or cathodic protection are required.
Even though RPMP pipe is officially designated a flexible conduit, its structural integrity is such
that for most installations, the trench preparation and backfill requirements are considerably less
than with other flexible conduits, and even some rigid ones. Its other advantages include
lightweight and a smooth, glass-like interior surface. RPMP sewer pipe is available in diameters
200 mm (8-inch) through 3,300 mm (144-inch), and in laying lengths of 3, 6, and 12 meters (10,
20 and 40 feet). Pipe joints are made with grooved couplings or bell and spigot joints utilizing
rubber O-ring gaskets.
l. Vitrified clay (V.C.) pipe is manufactured from clay and shale products to form an ideal
material for sewer use. V.C. pipe has a high resistance to corrosion from acids and alkalies, and
resists scouring and erosion well. This provides a distinct advantage in serving as industrial
waste sewers, or sanitary sewers subject to hydrogen sulfide generation. It should be noted that
availability of some sizes and strength classifications is limited in certain geographical areas.
(4-inch) through 1,000 mm (42-inch), and laying lengths of 300 mm to 3 meters (1 to 10 feet).
Clay pipe is manufactured in Standard and Extra Strength classifications. The Clay Pipe