Safety Requirements and Special Types of Polypropylene

Highest Safety Requirements

Polypropylene is a thermoplastic material from the group of polyolefins. These plastics have been successfully used in pipe manufacturing for decades. Under high safety requirements, polypropylene is also used in the automotive industry and in tank systems. Its hygienic harmlessness, corrosion resistance, and good processability, along with many other aspects, are prerequisites for a wide range of applications. Its physiological harmlessness qualifies polypropylene as an optimal material for drinking water pipes and other applications subject to food safety regulations.

Special PP Types

Due to the numerous specific requirements in chemical piping and apparatus construction, flame-retardant or electrically conductive special types have been developed. For example, during the operation of thermoplastic piping systems, static charges can arise due to the flow of liquids or dusts. Therefore, electrically conductive polypropylene types have been developed so that these piping systems can be grounded. The modified properties are achieved by adding additives. However, this results in changes to the mechanical, thermal, and chemical properties compared to the standard type. It is therefore necessary to clarify all projects with the application engineering department.

Differences Compared to Standard PP Types

PP-R, black:

(Polypropylene random copolymer, black colored) The main advantage of this black-colored material type lies in its UV resistance, which is not present in gray PP. However, a slight decrease in impact strength should be noted.

PP-R, natural:

(Polypropylene random copolymer, natural) Natural PP-R contains no color additives and is primarily used for ultrapure water piping systems. However, this material is not UV-resistant.

PP-HM

High-stiffness polypropylenes (PP-HM, E-modulus > 1700 N/mm2) belong to the material class of polypropylene block copolymers (PP-B) and are characterized by a comparatively high E-modulus in combination with high notched impact strength down to -20 °C. These properties make PP-HM an ideal material for non-pressure wastewater pipes. Another advantage is demonstrated, for example, by comparing PP-HM with PVC-U: the low specific weight of PP-HM materials (approx. 0.9 g/cm3) results in approximately 25% lower meter weights for ring stiffness class SN 8.

PP-H-s:

(Polypropylene homopolymer, flame-retardant) Due to the higher stiffness of PP-H-s, it is particularly suitable for ventilation pipes and exhaust gas ducts. However, it is not suitable for outdoor use without protective measures due to the lack of UV stabilization.

PP-R-s-el:

(Polypropylene random copolymer, flame-retardant, electrically conductive) This material combines the positive properties of flame-retardant and electrically conductive PP types. For safety reasons, it is therefore primarily used for the transport of highly flammable media. Reduced impact strength and long-term strength, as well as slightly altered chemical resistance, must be considered in the design.

Further information:
Overview of advantageous properties