QSC 5/8-18 LH Threaded Weld-In Bung

The QSC 5/8-18 LH Threaded Weld-In Bung addresses a specific fabrication requirement: creating a permanent, left-hand threaded connection point at the end of 1-1/4" OD tube with .120" wall thickness. The left-hand thread convention is engineered for assemblies — most commonly suspension components, steering tie rods, or roll cage hardware — where the rotational direction of service loads would progressively back out a standard right-hand thread. Using the correct thread hand is a structural specification, not a preference. The bung is pressed into the tube bore and welded to form a joint that transfers load through the weld rather than depending on thread engagement alone for retention.

Material is 1045 mild steel, a medium-carbon steel with sufficient hardenability for most structural tube applications and full compatibility with MIG and TIG welding. The plain exterior finish means the part arrives ready for fabrication without coatings to strip at the weld zone — but it also means corrosion protection is entirely the fabricator's responsibility post-weld. There are no published load ratings or third-party certifications for this component, which is standard for catalogue fabrication hardware of this type; engineering validation for a specific application rests with the builder. At 3.8 oz per unit, it's a straightforward procurement item when the thread spec and tube dimensions match the application requirement exactly.