Hydraulic fluid power - Flange connections with split or one-piece flange clamps and metric or inch screws - Part 2: Flange connectors, ports and mounting surfaces for use at a pressure of 42 MPa (420 bar), DN 13 to DN 76
1Key Takeaways
This document gives general and dimensional specifications for flanged heads, split flange clamps (FCS and FCSM), one-piece flange clamps (FC and FCM), ports and mounting surfaces applicable to fourscrew, split and one-piece flange clamp type tube connectors and hose fittings for use at a pressure of 42 MPa (420 bar1))…
2Expert Interpretation
This in-depth analysis of ISO 6162-2:2018, the international standard for hydraulic fluid power flange connections, covers key technical requirements such as dimensional tolerances, material selection, and corrosion protection for split and integral flange clamps in 42 MPa high-pressure environments. It also provides a complete implementation plan and installation torque data for sizes from DN13 to DN76.
Analysis of the Standard's Core Content
The third edition of ISO 6162-2 specifies the connection standards for split-type (FCS/FCSM) and integral-type (FC/FCM) flange clamps for hydraulic systems rated at 42 MPa (420 bar). For the first time, the standard specifies that the flange head must be machined with a 1-1.5mm wide identification groove, a key distinguishing feature from earlier versions.
Material requirements: The minimum yield strength of the flange clamp is 330 MPa, and the minimum yield strength of the flange head is 215 MPa. Bolts must be high-strength fasteners of Grade 10.9 (metric) or Grade 8 (imperial). Seals utilize NBR O-rings with a hardness of 90±5 IRHD.
Comparison of key technical parameters
| Specifications | Type 1(Metric) | Type 2(Imperial) |
|---|---|---|
| Applicable size range | DN13-DN76 | DN13-DN51 |
| Bolt grade | ISO 4017 Grade 10.9 | SAE J429 Grade 8 |
| O-Ring standard | ISO 3601-1 Class A | |
| Maximum working pressure | 42MPa(-40℃~+120℃) | |
Implementation Points
Installation Sequence Requirements: A cross-tightening sequence must be used (as shown in Figure A.1), with torque applied in stages to the specified value. The final torque value for a DN25 flange is 70N·m±10%, while for a DN51 flange, it must reach 550N·m.
Corrosion Protection Requirements: Carbon steel flange clamps must pass a 72-hour neutral salt spray test, while welded flange heads must meet a minimum 16-hour test. Cadmium plating is strictly prohibited; phosphate coating is recommended.
Standard Evolution Analysis
Major changes in the 2018 version include: repositioning the identification groove, adding chamfer requirements for the O-ring groove, and clarifying the threaded hole perpendicularity tolerance (0.25mm). Compared with the 2012 version, the new version improves the reliability of flange joints under pulse pressure through optimized structural design.
Typical Application Examples
In construction machinery hydraulic systems, a DN32 flange connection uses an FCMx32 clamp with a P32M port, M12×45 bolts (grade 10.9), and a size 228 O-ring, which can stably withstand a working pressure of 35MPa.