Plastic pipes, made from polymers like PVC, PE, and PP, offer advantages over traditional materials such as lead or copper due to properties like lower weight, corrosion resistance, flexibility, and ease of connection. These pipes are used in both pressure (gas, water) and non-pressure (drain, waste, venting (DWV), sewers) applications. Standards bodies globally ensure good practices for production and installation. Pipe standards and dimensions vary significantly worldwide.
In the USA, common standards include ASTM (American Society for Testing and Materials), with sizes like IPS (Iron Pipe Size), CTS (Copper Tube Size), and C900/C905 for pressure pipes. Japan uses the JIS (Japanese Industry Standard), while Europe primarily follows ISO (International Standard Organisation) and EN (European Norm) standards, though ISO is gaining traction elsewhere. National and US State standards also apply.
For pressure pipes, the design is based on material strength and safety factors. ISO standards utilize Renard figures and extrapolate material strength over 50 years to determine the Minimum Required Strength (MRS). ASTM standards use the Hydrostatic Design Basis (HDB) and extrapolate over 11 years. While similar, there are differences.
Safety factors (C) in pressure pipe design (PN = MRS * (SDR-1) / (2*C)) differ regionally. For PVC water pipe, Europe often uses C=2, resulting in a PN10 pipe for SDR26 with MRS=250 bar. Germany, however, uses C=2.5 for the same pipe, resulting in PN8. Safety factors depend on material toughness, ductility, failure mode, load application, pipe laying conditions, and national rules. PE materials, showing crack tip blunting, may have safety factors as low as 1.25 for water pipes. Modified PVC (MPVC) and Oriented PVC (PVCO) have lower safety factors (1.4-1.6) than standard UPVC (2-2.5), though MPVC also has a lower MRS.
For non-pressure pipes, stiffness is key to resist soil loads. Pipe Stiffness (PS) or Ring Stiffness (STIS) is measured differently. ASTM uses PS in psi, while ISO and EN use STIS in kPa. Structured Wall Pipe standards like EN13476, ISO 21138, and AS/NZS 1260 are functional, prescribing minimum stiffness rather than wall thickness, with some minimum composition requirements like 60-80% PVC content. ASTM F891 is a standard for PVC Cellular DWV pipe. ASTM standards for foam core require closed cells to prevent axial leakage. US sewer standards typically limit mean deflection to 7.5%.
Material choices also vary regionally; CPVC is widely used for Hot and Cold applications in the USA and India. ABS finds use in cold climates like Canada for higher impact resistance and in regions like California where PVC faced bans; ASTM F628 covers ABS Cellular DWV pipe. Jointing preferences differ, with rubber seal joints common for PVC connections and butt welding or electro fusion for PO, though PVC butt welding is promoted for specific applications.