PVC Extrusion and POLYOLEFIN Compounding

PO pipes, up to 2600 mm in diameter, are widely used in the mains infrastructure of integrated water cycles: from uptake with withdrawal of the resource from the water catchment areas, to water treatment plants up to storage in water tanks and supply to users. Thy are increasingly widespread in the natural gas supply chain as well, in diameters up to 250 mm, for distribution and supply to the end consumers’ domestic mains.

The features of PO pipes comply with the requirements for the following types of applications:

• High resistance to internal pressure and heat for pipes intended for heating and hot water.
• Maximum gas tightness for pipes of heating systems in order to prevent the corrosion of metal components caused by oxygen penetration and diffusion. In this connection, the materials PE-X, PE-RT, PP-R, PB and C-PVC, in addition to guaranteeing conformity to the requirements for plastic pipes, are the most suitable for these applications in the multi-layer version with oxygen barrier consisting of an aluminium or EVOH layer.

Pipes for residential installation

• PE-Xc 4-layer pipe with EVOH oxygen barrier
• PE-RT 5-layer pipe with EVOH oxygen barrier
• Hot water pipe in fibreglass PP-R

The segment relating to cable protection in electrical installations as well as in telecommunications sees plastic ducts increasingly taking centre stage, owing to their mechanical properties in terms on crushing and impact resistance. The former feature is the most important one, as the underground cable line is subject to the static load above compounded by the stresses caused by the soil covering it. The latter feature concerns accidental impacts with stones in the ground, being dropped against the surface of the item while it is being laid underground. We are able to meet the needs of manufacturers of different types of cable lines: smooth, corrugated, multiple ducting systems as well as mini-ducts for fibre optic cables, an application that is going through rapid growth.

Favoured over cast iron or vitrified clay, polyolefins (PO) assure high resistance to abrasion, corrosion, thermal oxidation, chemical agents and impacts. They feature dimensional stability, related to the degree of soil compaction, assuring a low degree of deformation and high elasticity, which means the duct is not liable to collapsing, permanently warping or cracking, resulting in a service life that may reach up to 100 years. In particular, the latest generation polypropylene (PP-HM) shows an even higher resistance than traditional polypropylene as well as other plastic materials normally used in ducting. Its excellent inertia to medium-high temperatures (up to 60°C and for a limited time even to 90°-110°C) makes it especially suitable for drain pipes, civil as well as industrial.

The activities for extraction of materials from mines and drilling for Oil & Gas extraction require pipes and fittings capable of withstanding heavy duty conditions and extreme stress. In the past, steel pipes were used as conveyance systems in mines, despite certain limitations, such as the noise level generated by sewage conveyance and contamination caused by the inevitable abrasion of steel. As a consequence, large diameter, thick pipes are favoured nowadays, manufactured in PE 100, whose polymer chains have properties and features specifically designed to manage and limit the effects of scratches, cuts and concentrated loads.

PO pipes meet the strict regulations concerning underground drainage in the civil and agricultural sector –where infiltrations may cause severe damage – to collect and promote removal of excess water. In addition to road infrastructures, typical polypropylene applications are the drain pipes for railway tracks, airports and tunnels, heavily exposed to high static and dynamic loads. Polyethylene (PP) is preferred for bicycle and pedestrian lanes. Finally, polyolefins (PO) are the most efficient solution also to correct and regulate the quantity of water in agricultural land, averting the danger of crop flooding and asphyxiation of the root system.

Ground source heat pumps are the most efficient source of heating and cooling energy for any type of building. The most common plastic piping materials used for geothermal systems is PE. Geothermal heat pumps can have efficiencies (COP) greater than 450% when operating in heating mode. Strong and tough material, suitable for applications up to 180°F (82°C) and beyond.

Resistant to chemicals and salts, physical impacts and corrosion, the most suitable pipes for this application must also assure high plastic flow properties and low heat dispersion. In this sector, PEX-A crosslinked Polyethylene stands out. A form of cross-linked polyethylene, produced by peroxide cross-linking, it makes it possible to produce high quality pipes with excellent performance. The extrusion process requires the polymer to be kept at high temperatures and pressures for a long time, so that it can be used in applications where the thermal resistance requirements are very stringent, as is the case with district heating, geothermal plants and the healthcare and industrial sector.