ISO 161-1-2018 PDF

Full title and description

Thermoplastics pipes for the conveyance of fluids — Nominal outside diameters and nominal pressures — Part 1: Metric series. Specifies metric nominal outside diameters (dn), nominal pressure ratings (PN) and minimum required strengths (MRS) for smooth thermoplastics pipes of constant circular cross-section used for the conveyance of fluids, and provides a basis for product standards and specification writers.

Abstract

ISO 161-1:2018 defines the preferred metric outside diameters and associated nominal pressure ratings for thermoplastics pipes, and gives rules for minimum required strength (MRS) and the use of preferred‑number series when selecting PN and MRS values. It applies to smooth, constant-section thermoplastics pipes (pressure and non‑pressure use) and is intended as a reference for standards writers, manufacturers and designers.

General information

• Status: Published (International Standard confirmed).
• Publication date: January 2018 (ISO 161-1:2018). Amendment 1 published April 25, 2023.
• Publisher: International Organization for Standardization (ISO), prepared by ISO/TC 138.
• ICS / categories: 23.040.20 (Plastics pipes).
• Edition / version: Edition 4 (2018); amended by ISO 161-1:2018/Amd 1:2023.
• Number of pages: Main document — 5 pages; Amendment 1 — 2 pages (combined normative content varies by published package).

Scope

ISO 161-1:2018 applies to smooth thermoplastics pipes of constant circular cross-section for conveyance of fluids in pressure and non‑pressure applications. The standard specifies nominal outside diameters (metric series), associated PN values and rules for minimum required strengths (MRS) and rounding using preferred‑number series. It does not apply to pipes designated by nominal inside diameter (DN/ID). The document is intended primarily as a framework for use in product standards rather than to replace individual product specifications.

Key topics and requirements

• Definition and tabulation of metric nominal outside diameters (dn) for thermoplastics pipes up to large sizes following preferred‑number series.
• Selection and definition of nominal pressure ratings (PN) drawn from preferred‑number (R series) values and clarification of special cases (for example PN 6 handled as 6.3 bar from the R‑10 series).
• Minimum required strength (MRS) concept — MRS as a lower confidence limit of long‑term hydrostatic strength at 20 °C for 50 years, rounded to preferred‑number series values.
• Relationship between MRS, design stress (σS = MRS/C where C is design coefficient per ISO 12162) and hydrostatic stress calculations for internal pressure.
• Terminology and measurement rules (outside diameter, mean outside diameter, minimum mean outside diameter) to ensure consistency in product standards.

Typical use and users

ISO 161-1:2018 is used by standards writers and technical committees when drafting thermoplastics pipe product standards; by pipe and fittings manufacturers specifying nominal sizes and PN ratings; by pipeline, mechanical and civil engineers for system selection and hydraulic design; by testing and certification bodies evaluating long‑term pressure performance; and by procurement and regulatory authorities harmonizing requirements across projects.

Related standards

Key related documents include ISO 3 (preferred numbers — R series) and ISO 12162 (thermoplastics materials for pipes and fittings for pressure applications — classification and design coefficient). ISO 161 consists of multiple parts: Part 1 is the metric series (this document) and Part 2 covers the inch‑based series (ISO 161‑2:1996). Amendment ISO 161-1:2018/Amd 1:2023 updates specific entries and clarifications in the metric series.

Keywords

thermoplastics pipes, nominal outside diameter, nominal pressure (PN), minimum required strength (MRS), metric series, preferred numbers, ISO 161, ISO/TC 138.

FAQ

Q: What is this standard?

A: ISO 161-1:2018 is an International Standard that defines metric nominal outside diameters and nominal pressure ratings for thermoplastics pipes used to convey fluids, and gives rules for minimum required strength (MRS) and preferred‑number rounding used in product standards.

Q: What does it cover?

A: It covers smooth, constant‑section thermoplastics pipes in metric sizes, specifying dn values, PN choices and principles for MRS and design stresses. It is a reference framework for product standards rather than a full product specification. It does not apply to pipes designated by nominal inside diameter (DN/ID).

Q: Who typically uses it?

A: Standards developers, pipe and material manufacturers, design engineers, test laboratories, certification bodies and procurement/regulatory authorities use ISO 161-1 when defining or selecting pipe sizes, pressure ratings and strength classes.

Q: Is it current or superseded?

A: ISO 161-1:2018 is the current edition (published January 2018) and has been amended by ISO 161-1:2018/Amd 1:2023 (published April 25, 2023). The 1996 edition was superseded by the 2018 edition.

Q: Is it part of a series?

A: Yes — ISO 161 is a multi‑part series. Part 1 is the metric series (this standard); Part 2 covers the inch‑based series (ISO 161‑2:1996). Other related ISO documents (for example ISO 3 and ISO 12162) are commonly referenced for preferred numbers and material/design coefficients.

Q: What are the key keywords?

A: thermoplastics pipes; nominal outside diameter (dn); nominal pressure (PN); minimum required strength (MRS); preferred numbers; metric series; ISO 161.