EN ISO 8434-1:2018

Overview

EN ISO 8434-1:2018 (Corrected version 2018-10) specifies general and dimensional requirements for 24° cone connectors for metallic tubes used in fluid power and general applications. It covers connectors that use a cutting ring and O‑ring seal cone (DKO) and are suitable for ferrous and non‑ferrous tubes with outside diameters from 4 mm to 42 mm inclusive. The standard is implemented by CEN and aligns with ISO 8434‑1:2018.

Key topics and technical requirements

• Connector types covered: 24° cone connectors with cutting ring and O‑ring seal cone (DKO).
• Tube compatibility: Plain end tubes and hose fittings; intended for tubes 4–42 mm OD.
• Ports and interfacing standards: Designed to mate with ports in accordance with ISO 6149‑1, ISO 1179‑1 and ISO 9974‑1 (see ISO 12151‑2 for related hose fittings).
• Pressure and temperature: Defines applicable pressure/temperature limits and refers to working pressures listed in the document (Table 1). Values are not guaranteed minimums - application-specific testing is required.
• Materials and manufacture: General material and construction guidance for connector bodies, nuts, cutting rings and O‑rings to ensure reliability and interchangeability.
• Design and dimensional requirements: Detailed dimensional, passage and angular tolerances, across‑flats sizes, screw thread specifications, contour details, and stud end sealing.
• Performance and qualification tests: Includes repeated assembly, proof test, burst pressure, cyclic endurance (impulse), vibration, leakage (gas), overtightening, and vacuum tests to qualify connectors and assemblies.
• Assembly and procurement: Normative assembly instructions (Annex A), marking, and procurement information to support correct use and traceability.

Applications and who uses this standard

EN ISO 8434-1:2018 is essential for:

• Hydraulic system designers and OEMs specifying full‑flow hydraulic connections.
• Connector and tube manufacturers producing compatible 24° cone fittings.
• Maintenance and service engineers selecting replacement fittings for fluid power systems.
• Test laboratories performing qualification and performance testing.
• Procurement and quality assurance teams ensuring compliance and interoperability.

Typical applications include mobile and industrial hydraulics, pneumatic and pressurized fluid lines, and general-purpose piping where reliable, leak‑resistant metal tube connections are required.

Related standards

• ISO 8434 series (other parts)
• ISO 6149‑1, ISO 1179‑1, ISO 9974‑1 (port/interface standards)
• ISO 12151‑2 (related hose fitting specification)

Keywords: EN ISO 8434-1:2018, 24° cone connectors, metallic tube connections, cutting ring, O‑ring seal cone, DKO, fluid power, hydraulic connectors, ISO 8434.