ISO 11299-3:2018

Overview - ISO 11299-3:2018 (Close-fit lining for gas networks)

ISO 11299-3:2018, titled Plastics piping systems for renovation of underground gas supply networks - Part 3: Lining with close-fit pipes, specifies requirements and test methods for close-fit lining systems used to renovate existing underground gas distribution pipelines. It is a part of the ISO 11299 series and is intended to be used in conjunction with ISO 11299‑1 (General). The standard applies to polyethylene (PE) pipes (solid wall single layer or co‑extruded) that are factory‑ or site‑reduced to form a close‑fitting independent or interactive pressure liner, plus associated fittings and joints and the installed lining system. Reference operating temperature is 20 °C; guidance for other temperatures is given in ISO 4437‑5:2014.

Key topics and technical requirements

• Scope & applicability: Covers materials, manufacturing, installation condition (“as‑manufactured” and “as‑installed”), and excludes PE pipes with a peelable outer thermoplastic coating.
• Materials & compounds: PE compound requirements reference ISO 4437 series; each co‑extruded layer must meet MFR and OIT requirements where specified.
• Product stages: Defines “M” (manufactured/processed) and “I” (installed) stages and requires verification of certain characteristics in the installed condition - a key distinction for renovation standards.
• Mechanical & physical tests: Includes hydrostatic strength testing (example: hydrostatic strength at 80 °C, 165 h is referenced), memory/heat‑reversion properties for folded pipes, and other performance tests to demonstrate fitness for purpose.
• Joints & jointing methods: Butt fusion and electrofusion joints are covered; butt fusion must conform to ISO 4437‑2 and ISO 4437‑5 and be properly de‑beaded where required.
• Design parameters & symbols: Uses standard piping design concepts such as MRS (Minimum Required Strength), MOP (Maximum Operating Pressure), LPL (Lower Confidence Limit), SDR and dimensional tolerances.
• Marking & documentation: Pipe and fitting marking requirements are aligned with ISO 11299‑1 and ISO 4437 series; manufacturers must declare “M” stage dimensions needed to achieve “I” stage geometry.

Practical applications and who uses this standard

ISO 11299‑3:2018 is designed for:

• Gas utility owners and network operators planning trenchless renovation using close‑fit liners
• Pipeline engineers and designers specifying PE close‑fit lining systems
• Manufacturers of PE close‑fit pipes, fittings and joints who need to demonstrate conformity
• Contractors and installation teams performing factory or on‑site pipe reduction, reversion and jointing
• Testing laboratories and conformity assessment bodies validating “as‑installed” performance

Typical applications include rehabilitation of aging buried gas mains where a close‑fitting PE liner restores pressure integrity without full pipe replacement.

Related standards

• ISO 11299‑1 (General requirements for renovation systems)
• ISO 4437 series / EN 1555 series (PE piping for gaseous fuels)
• ISO 3126 (Dimensions), ISO 12176 (fusion equipment)
• Other parts of ISO 11299 (Parts 2, 4, 6, 11) for alternative lining techniques

Keywords: ISO 11299-3:2018, close-fit lining, polyethylene (PE) pipe, renovation of underground gas supply networks, lining systems, trenchless rehabilitation, MRS, MOP, hydrostatic strength, butt fusion, electrofusion.