Overview
EN ISO 12162:2009 - Thermoplastics materials for pipes and fittings for pressure applications - defines how thermoplastic pipe materials are classified, designated and used to calculate design stress for pressure applications. The standard establishes a material classification based on long‑term hydrostatic strength, specifies the minimum required strength (MRS) designation, introduces the categorized required strength (CRSθ,t) for other temperatures/times, and sets principles for the design coefficient (C) used to derive allowable design stresses.
Key Topics and Requirements
- MRS classification: Materials in pipe form are classified by the 97.5% lower confidence limit of predicted long‑term hydrostatic strength (σLPL) at 20 °C and 50 years, rounded down to the next R10 or R20 preferred number. The MRS classification number = 10 × MRS (MPa). Example designation: PVC‑U 250 (MRS 25 MPa).
- CRSθ,t (categorized required strength): CRSθ,t values allow design at temperatures/times other than 20 °C/50 years. CRS values are derived from σLPL at the chosen temperature θ and time t and rounded to R10/R20 series. CRS is not intended for applications with varying temperature profiles (see ISO 10508).
- Design coefficient (C and Cmin): A design coefficient >1 accounts for service conditions and effects not covered by σLPL. Product (system) standards specify C; EN ISO 12162 gives minimum design coefficients (Cmin) for common thermoplastics (examples include PE, PP, PVC types, PVDF, ABS, PA11/12, PPSU).
- Design stress calculation:
- Based on MRS: σs = MRS / C
- Based on CRS: σs,θ,t = CRSθ,t / C
Maximum allowable design stress is normally calculated using Cmin unless the product standard requires otherwise.
- Normative references: ISO 9080 (long‑term hydrostatic strength extrapolation) and ISO 1043‑1 (polymer symbols) are integral to application.
Practical Applications
- Selection and specification of thermoplastic materials for pressure pipes and fittings (water, industrial fluid transport).
- Determining allowable stresses for design and system engineering using material MRS or CRS values.
- Lab testing and certification workflows that generate σLPL data used in MRS/CRS classification.
- Basis for product/system standards that set application‑specific coefficients and additional property requirements.
Who Uses This Standard
- Piping system designers and civil/mechanical engineers
- Pipe and fitting manufacturers
- Test laboratories and materials engineers
- Standards committees, regulatory bodies and procurement/specification professionals
Related Standards
- ISO 9080 - Determination/extrapolation of long‑term hydrostatic strength
- ISO 1043‑1 - Polymer symbols and abbreviated terms
- ISO 10508 - Guidance for piping systems with temperature profiles
EN ISO 12162:2009 is essential for consistent, reliable classification and safe design of thermoplastic pressure piping systems.