ISO 21052-2021 PDF

Full title and description

ISO 21052:2021 — Restrained joint systems for ductile iron pipelines — Calculation rules for lengths to be restrained. This International Standard specifies a computation method to determine the length of ductile iron pipe runs that must be restrained (thrust restraint) for buried pipelines conveying raw water, drinking water and sewerage under pressure.

Abstract

The standard defines a calculation procedure for estimating the lengths of ductile iron pipe that require mechanical restraint to resist hydraulic thrusts and other forces. The method accounts for common pipeline route changes (bends, tees, reducers), changes in pipe diameter, dead ends, external pipe diameter, system test pressure (for thrust estimation), depth of cover, surrounding soil characteristics and trench backfill methods so it can be applied worldwide. The standard is applicable to all types of restrained joint systems; however, it does not prescribe the detailed characteristics of any specific restrained joint type (those can be considered separately when determining restraining lengths).

General information

• Status: Published
• Publication date: November 2021
• Publisher: International Organization for Standardization (ISO)
• ICS / categories: 23.040.10 (Iron and steel pipes)
• Edition / version: Edition 1 (ISO 21052:2021)
• Number of pages: 26

Scope

ISO 21052:2021 provides a calculation method to determine lengths of ductile iron pipe that must be restrained to prevent movement under pressure and operational loads. It applies to buried ductile iron pipelines used for conveying raw water, drinking water and pressurized sewerage, and covers typical route changes, diameter changes and dead ends. The method is intended for use with pipelines manufactured and jointed in accordance with relevant ductile iron standards; it does not itself specify the mechanical design of restrained joints.

Key topics and requirements

• Computation method for determining required restrained lengths (thrust restraint) along a pipeline.
• Consideration of pipeline geometry: bends, tees, reducers, dead ends and diameter changes.
• Inputs include outside pipe diameter, system/test pressure (for thrust estimation), burial depth, soil properties and trench backfill method.
• Applicable to all types of restrained joint systems; standard does not prescribe joint construction details or restraint product specifications.
• Intended for use in conjunction with product standards for ductile iron pipes and joints (references such as ISO 2531, ISO 7186, ISO 16631).
• Provides a harmonized, internationally applicable approach to resist hydraulic thrusts and limit pipeline movement.

Typical use and users

Engineers and designers of water and sewerage infrastructure, utility technical teams, pipeline contractors, geotechnical and civil consultants, manufacturers of restrained-joint systems and fittings, testing laboratories and regulatory authorities use this standard to size and locate thrust restraint for buried ductile iron pipelines and to ensure consistent calculation practice across projects and jurisdictions.

Related standards

ISO 21052 is intended to be used alongside product and installation standards for ductile iron pipelines, for example: ISO 2531 (ductile iron pipes, fittings, accessories and their joints for water applications), ISO 7186 (ductile iron products for sewerage applications), ISO 16631 (ductile iron pipes, fittings and joints compatible with plastic piping systems), ISO 10804 / ISO 10802 (design and hydrostatic testing of ductile iron pipelines), ISO 16134 (earthquake- and subsidence‑resistant design of ductile iron pipelines) and ISO 21051 (construction and installation of ductile iron pipeline systems). These related documents cover material, jointing, installation and special design requirements that complement the restrained-length calculations in ISO 21052.

Keywords

restrained joint, thrust restraint, ductile iron, pipeline, restrained length, calculation method, hydraulic thrust, burial depth, soil, trench backfill, water distribution, sewerage, pipeline design

FAQ

Q: What is this standard?

A: ISO 21052:2021 is an international standard that specifies calculation rules for determining the lengths of ductile iron pipe that must be restrained (thrust restraint) in buried pipelines carrying water and pressurized sewerage.

Q: What does it cover?

A: It covers a computation method that accounts for pipeline geometry (bends, tees, reducers, dead ends), pipe diameter changes, outside diameter, system/test pressure, burial depth, soil characteristics and trench backfilling to estimate required restrained lengths. It does not prescribe specific restrained-joint designs or product specifications.

Q: Who typically uses it?

A: Pipeline designers and civil engineers, utility and municipal engineering departments, contractors installing ductile iron mains, manufacturers of restrained-joint systems, and testing/inspection bodies use the standard to plan and verify thrust restraint requirements.

Q: Is it current or superseded?

A: ISO 21052:2021 was published in November 2021 (Edition 1). As of its publication it is the current international standard on this topic; users should check with national standards bodies or ISO for any subsequent amendments or newer editions when applying the standard to projects.

Q: Is it part of a series?

A: It is part of the body of ISO guidance and product standards dealing with ductile iron pipeline systems and their design/installation (see related standards such as ISO 2531, ISO 7186, ISO 16631, ISO 21051 and others). It specifically addresses restrained-joint length calculation and complements those product and installation standards.

Q: What are the key keywords?

A: Restrained joint, thrust restraint, ductile iron pipeline, calculation rules, restrained length, hydraulic thrust, soil, trench backfill, water mains, sewerage under pressure.