Midland Industries 30431 Lh Welding Stem Nut Brass 1/4 in Barb

Product Description

The MIDLAND INDUSTRIES 30431 is a left-hand thread welding stem and nut assembly designed for acetylene and fuel-gas hose connections in welding and cutting applications. Constructed from brass, this fitting combines a 1/4-inch hose barb on one end with a 9/16-18 LH UNF threaded connection on the other. The left-hand thread configuration is a standard safety convention for fuel-gas lines, preventing accidental interchange with oxygen-side fittings. It carries a maximum operating pressure of 150 psi and is rated for service from -40 to 160 degrees F, making it suitable for typical shop and field welding environments. Plumbers, pipefitters, and welding equipment technicians are the primary installers.

This assembly is used on acetylene hose lines in oxy-fuel welding, cutting, and brazing setups. The 1/4-inch hose barb end accepts standard fuel-gas welding hose, while the 9/16-18 LH UNF threaded end connects to regulators, torches, or manifold fittings that use the left-hand thread standard. It is appropriate for both portable and fixed welding stations in residential shops, commercial fabrication facilities, and field service applications. The brass construction provides corrosion resistance and good sealing characteristics for low-to-medium pressure gas service.

Key Features

• Left-hand thread (9/16-18 LH UNF) meets fuel-gas safety convention, preventing mix-up with oxygen fittings
• 1/4-inch hose barb end accepts standard acetylene welding hose
• Brass construction offers corrosion resistance for gas service environments
• Rated to 150 psi maximum operating pressure
• Wide temperature range: -40 to 160 degrees F
• Compact profile at approximately 1.35 inches in length

Compatibility

Designed as an OEM-style replacement or service fitting for acetylene-side welding hose assemblies using a 1/4-inch hose barb inlet and 9/16-18 LH UNF threaded outlet, consistent with standard fuel-gas line fittings.

Installation Notes

Installation should be performed by a qualified pipefitter, welding equipment technician, or similarly trained trade professional. Always close the cylinder valve and bleed all pressure from the hose before disassembling or replacing any fitting. Left-hand threads tighten counterclockwise - do not apply excessive force or use tools that could deform the brass threads. After assembly, leak-test all connections with an approved leak-detection solution before returning the system to service; never use an open flame to check for leaks.