Pipes are manufactured using the "Dual helix" filament winding process on computer controlled machines. By adjusting the relative speed of mandrel rotation and glass distribution head movement, helical reinforced layers with different angles can be wound. In order to increase the pipe stiffness, especially on large diameter pipes, silica sand can be added to parallel layers of wall.

For general considerations it is important to take into account that according to the loading of the system and the pressure class, the glass fibres can be helically wound under a predetermined angle with the axis of the pipe, that can also vary layer by layer according to design between 45°-88°, which may confer specific design product characteristics.

Nominal size of pipe and fitting is based on internal diameter. The range of available sizes is 25 to 3000 mm.

Pipes and fittings are classified according to nominal pressure. Standard pressure classes are 4, 6, 10, 16, 20 and 25 bars. Intermediate or higher-pressure classes are considered on request or depending on the design parameters and conditions.

Pipes are also classified according to specific pipe stiffness. Standard stiffness classes are 1250, 2500, 5000 and 10000 Pa. Intermediate or higher stiffness classes are available on request or depending on the design conditions.

The standard GRP pipes and fittings produced by Iniziative Industriali are described in detail in the document GRP PIPING PRODUCT LIST.

A wide range of fittings as elbows, reducers, tees, caps, flanges etc. is available.

Fittings are manufactured by the hand lay-up, contact molding and spray-up process. In hand lay-up and contact molding processes veil and alternate layers of mat and woven roving saturated with resin are applied on the mold. In spray-up process continuous strand roving is fed through a chopper gun, combined with catalyzed resin, and sprayed onto the mould surface.