SAE J518 Hydraulic Flanges — Code 61 & Code 62

What is an SAE J518 Hydraulic Flange?

SAE J518 defines four-screw flange connections for hydraulic systems where large threaded fittings would leak or be hard to tighten. A flanged head on the tube or hose carries an O-ring that seals against the port face; a one-piece or split flange clamp is bolted over the head with four screws. Part 1 covers Code 61, from 3.5 MPa to 35 MPa depending on size; Part 2 covers Code 62, rated 42 MPa (about 6,000 psi). The parts are interchangeable with ISO 6162-1 and ISO 6162-2. Code 61 and Code 62 have different bolt patterns and are not interchangeable.

Key features

• Code 61 (standard pressure) and Code 62 (high pressure) patterns
• One-piece flange clamps and split flange clamps
• Socket-weld, butt-weld and threaded flange variants
• O-ring groove machined to SAE J518 / ISO 6162
• Metric (Type 1) and inch (Type 2) screw versions

Specification

Applications

• Mobile hydraulics: excavators, cranes, loaders
• Industrial hydraulic power units and manifolds
• Steel and rolling mill hydraulics
• Hydraulic presses and injection machines
• Marine and offshore hydraulic systems

Code 61 vs Code 62

Code 61 flanges cover ½″ to 5″ at pressures from 3.5 MPa to 35 MPa, falling as size increases. Code 62 flanges cover ½″ to 3″ at 42 MPa (about 6,000 psi), with a larger flange head, thicker clamp and wider bolt pattern. The two are not interchangeable: the bolt spacing, head diameter and O-ring size all differ, so the port code must be confirmed before ordering.