CPI

GRE Technology

Glass Reinforced Epoxy or GRE pipes are a valid alternative to carbon steel pipes especially for corrosive, aggressive and normal environments.

GRE pipe technology is based on the Discontinuous Filament Winding process using high strength fiberglass (E-glass) and amine cured epoxy resin as basic material. Numerically controlled machines manufacture the product on a mandrel according to the cross section filament winding process. The continuous glass fibers are helically wound at predetermined angles and bonded with the epoxy resin.

Lightweight and easy to handle and install GRE pipes have a smooth internal surface that reduces friction and enables a high pipe flow capacity. Low thermal conductivity of GRE pipes in comparison to steel (only one percent of steel values), minimizes the cost of insulation and the heat loss. Another major benefit of GRE pipes is that once installed they are virtually maintenance-free.

GRE pipes are well suited for environments where the corrosion resistance at competitive prices is required.

GRE pipes offer a unique combination of high mechanical, thermal and chemical resistance which is obtained by the selection of high performance components and a proper design of the structure. The inner liner, which is made by a resin rich layer reinforced with C-glass or synthetic veil, guarantees the pipe water tightness, its chemical and temperature resistance. The mechanical resistant layer is composed of successive layers of pre-stressed glass roving impregnated with epoxy resin and orientated with a precise, predetermined angle selected in order to achieve the properties required. The resin and the hardener system are selected with the consideration of the combination of properties required from the finished product. The glass reinforcement in the form of continuous roving is chosen base on its compatibility with epoxy resin. It is applied on the rotating mandrel following the hoop (radial) winding pattern combined with a helical winding pattern at an angle ranging from 45° to 90°.

Glass tape or unidirectional reinforcements can be used to obtain local reinforcement. An external resin coating reinforced with a synthetic veil adds a finish to the pipe. Should weathering be a problem a UV inhibitor will be added to the coating.

GRE pipes are generally manufactured with an integral joint, which means that the socket (for bonding, lock, or thread) is produced simultaneously with the pipe body by winding on a specially designed metallic mould fixed at one end of the mandrel. The pipes are wound on precisely machined steel mandrels, the mandrel is extracted only when the pipe is cured.

ADVANTAGES

Why use GRE?
GRE
Cathode protection
No
Chemical resistance
High
Internal corrosion
No
External corrosion
No
Bacterial resistance
High
Anti-corrosive coating
No
Corrosion protector
No
Clearing pig
No
Life span (years)
over 20
Heavy equipment
No
Relative weight (vs. steel)
0,25
Required labour
Low
Installation time (vs. steel)
0,40
Installation cost
0,25
Welding
No
Radiography
No
Hazen-Williams
150
Thermal conductivity
<1 vs Steel
Paraffin build-up
Low
Carbonate buil-up
Low

General characteristics of the piping

Uses of GRE