ISO 21138-1:2020

Overview

ISO 21138-1:2020 specifies material requirements and performance criteria for structured‑wall piping systems made from unplasticized poly(vinyl chloride) (PVC‑U), polypropylene (PP) and polyethylene (PE) intended for non‑pressure underground drainage and sewerage. Part 1 is the material and performance backbone of the ISO 21138 series and is intended to be used together with ISO 21138‑2 (Type A, smooth external surface) and ISO 21138‑3 (Type B, non‑smooth or ribbed external surface). The standard covers a wide range of sizes, constructions and nominal ring stiffnesses (guidance up to DN/OD or DN/ID 1200) and includes recommendations on colour, joints and compatibility with other components.

Key topics and requirements

• Materials: Acceptable thermoplastics (PVC‑U, PP, PE) with general material characteristics and selection guidance.
• Performance criteria: Requirements for mechanical and physical performance relevant to non‑pressure sewer and drainage applications (see Clause 9 and informative annexes).
• Geometrical characteristics: Definitions and dimensional requirements (outside/inside diameter, wall thickness, waterway thickness, nominal size DN).
• Jointing: Compatibility of structured‑wall pipes and fittings with elastomeric ring seal joints, welded/fused joints and joints to other plastics or non‑plastic components-joint dimensions are coordinated with ISO 21138‑2 and ISO 21138‑3.
• Ring stiffness & installation: Relationship between nominal ring stiffness, installation technique and resulting deflection (guidance for selecting stiffness based on trenching/installation).
• Testing & references: Normative cross‑references to ISO test methods covering ring stiffness, watertightness, impact resistance, oven aging, melt flow, etc.
• Colours & identification: Recommendations for pipe/fitting colours to assist identification and use.

Practical applications and users

ISO 21138‑1 is used by:

• Manufacturers of structured‑wall PVC‑U, PP and PE pipes and fittings to define material and system performance.
• Specifiers, engineers and consultants who select piping systems for underground non‑pressure drainage, sewerage, highway drainage and surface water applications.
• Contractors and installers needing guidance on ring stiffness selection and jointing options for reliable installation.
• Regulators and procurement teams setting acceptance criteria for drainage infrastructure.

Use this standard when you need a harmonized material specification and performance baseline to ensure compatibility, durability and watertight performance of structured‑wall non‑pressure piping systems.

Related standards

• ISO 21138‑2 (Type A) and ISO 21138‑3 (Type B) - product‑specific dimensions and requirements
• Various ISO test standards referenced for ring stiffness, watertightness, impact and ageing (see normative references in ISO 21138‑1).