Midland Industries 6403O64 Union Hex Nipple Steel

Product Description

The MIDLAND INDUSTRIES 6403O64 is a steel union hex nipple designed to connect two hydraulic or fluid-system lines using O-Ring Boss (ORB) fittings on both ends. One side accepts a 3/8-inch Male O-Ring Boss connection threaded at 9/16-18, and the other accepts a 1/4-inch Male O-Ring Boss connection threaded at 7/16-20. The steel construction supports an operating temperature of up to 375 degrees F, making it suitable for demanding hydraulic service environments. Licensed plumbers, hydraulic system technicians, and fluid-power mechanics typically specify this type of adapter when routing lines between mismatched port sizes.

This union hex nipple fits within SAE O-Ring Boss hydraulic adapter assemblies, classified under the 6403 Series MORB Union family. It is used in industrial hydraulic circuits, mobile equipment fluid systems, and similar applications where a reducer-style union adapter is needed to transition between a 3/8-inch and 1/4-inch ORB port. Its hex body allows standard wrench installation without special tooling.

Key Features

• Reducer-style union connects 3/8-inch Male ORB to 1/4-inch Male ORB in a single fitting
• Thread 1: 9/16-18 (3/8-inch ORB); Thread 2: 7/16-20 (1/4-inch ORB)
• Steel construction rated to 375 degrees F operating temperature
• Hex body profile allows installation with standard open-end or combination wrenches
• Part of the 6403 Series SAE O-Ring Boss Union adapter line

Compatibility

Designed as an OEM-style replacement or new-installation fitting for SAE O-Ring Boss hydraulic adapter applications requiring a 3/8-inch to 1/4-inch Male ORB union connection in steel hydraulic systems.

Installation Notes

This fitting is installed by qualified hydraulic system technicians or licensed fluid-power mechanics. Depressurize and drain the hydraulic circuit fully before removing or installing any fittings. Apply thread sealant only if specified by the system manufacturer, as ORB fittings rely on the O-ring face seal for leak-free connection rather than thread sealant alone. Torque to the system or fitting manufacturer specifications and inspect for leaks after pressurizing the circuit.