ISO 22055:2019

Overview

ISO 22055:2019 - "Switch and crossing rails" - is an ISO international standard that specifies the requirements for switch and crossing rails used to carry railway wheels in conjunction with flat bottom (vignole) rails (see ISO 5003). The standard covers material grades, testing methods, dimensional and surface tolerances, inspection, identification and certification for rails as produced (excluding secondary processing such as forging, grinding or heat treatment, which are covered by other standards or contractual agreement). It defines sixteen pearlitic steel grades with a hardness range of 200 HBW to 440 HBW.

Key topics and technical requirements

ISO 22055:2019 addresses the full production-acceptance envelope for switch and crossing rails, including:

• Material grades: Sixteen pearlitic steel grades (non-heat-treated and heat-treated variants) covering a wide hardness range.
• Testing methods and frequencies: Requirements for chemical composition, hydrogen content, total oxygen, tensile tests, Brinell hardness, microstructure, decarburization, non‑metallic inclusions, macrostructure and ultrasonic testing. Sampling and frequency are specified (e.g., per heat, per sequence or per tonne as applicable).
• Mechanical and metallurgical checks: Tensile and hardness tests, microstructure and inclusion evaluation, and requirements for decarburization depth and macrostructure.
• Ultrasonic inspection: Whole-length ultrasonic testing requirements, calibration and sensitivity criteria for detecting internal defects.
• Dimensional and geometric tolerances: Length, profile dimensions, straightness, surface flatness, twist and weight tolerances for ready-for-track rails.
• Surface quality and identification: Surface finish requirements, branding, hot and cold stamping methods and other marking/traceability details.
• Inspection and certification: Acceptance criteria, retest procedures and certificate content required for delivery.

Practical applications and users

ISO 22055:2019 is directly relevant to:

• Rail manufacturers and steelmakers - for material specification, process control and acceptance testing of as‑produced switch and crossing rails.
• Railway infrastructure owners and asset managers - to specify procurement requirements and verify delivered rails meet safety and performance needs.
• Track component suppliers and fabricators - when supplying or processing switch & crossing rails (noting secondary processing is out of scope).
• Inspection bodies and test laboratories - for conducting the standardized mechanical, metallurgical and ultrasonic tests.
• Procurement and quality engineers - to define contract parameters such as rail profile, steel grade, inclusion class, lengths, drilled ends and paint codes.

Purchaser-supplied information required by the standard includes the rail profile, steel grade, inclusion determination method/class, macrostructure requirement, rail lengths, drilled/undrilled ends and paint code.

Related standards

Key referenced standards include:

• ISO 5003 (flat bottom / vignole railway rails)
• ISO 6892-1 (tensile testing)
• ISO 6506-1 (Brinell hardness)
• ISO 3887, ISO 4967, ISO 4968, ISO 4969 (metallographic and inclusion/macrostructure methods)

ISO 22055:2019 is essential for ensuring consistent quality, traceability and fitness-for-service of switch and crossing rails in rail track systems.