AC-12 HYBRID - High Pressure Cylinder Neck Ring 3-1/8-12 Fine Thread

Technical Overview: High Pressure Safety Collar (3-1/8" x 12 Fine Thread)

The AC-12 HYBRID High Pressure Safety Collar is a critical structural component designed for the maintenance and assembly of high-pressure gas cylinders. This collar, often referred to as a neck ring, provides the necessary external threading to accept a valve protection cap. The specification of 3-1/8 inches in diameter with 12 threads per inch (Fine Thread) indicates a specialized fitment intended for specific cylinder classes where fine thread engagement is required for superior vibration resistance and secure retention of the safety cap.

Manufactured from high-strength steel, this collar is engineered to withstand the rigorous demands of the industrial gas supply chain. The neck ring serves as the primary interface between the cylinder body and the safety cap, playing a pivotal role in protecting the cylinder valve—the most vulnerable point of a pressurized vessel—from shearing forces during transit or accidental tipping. The fine thread pitch (12 TPI) offers a tighter mechanical interlock compared to coarse threads, reducing the likelihood of the cap loosening due to handling vibrations or thermal expansion and contraction cycles.

In the context of cylinder requalification and maintenance, replacing a damaged or stripped collar is essential for keeping a cylinder in service. A collar with damaged threads prevents the attachment of a safety cap, rendering the cylinder illegal to transport under Department of Transportation (DOT) and other safety regulations. This AC-12 HYBRID unit ensures that cylinders can be properly capped, stored, and transported, maintaining full compliance with industrial safety standards. It is suitable for use on a variety of high-pressure vessels requiring this specific thread profile, ensuring seamless integration into existing cylinder fleets.

Key Technical Specifications:

• Thread Diameter: 3-1/8 Inches


• Thread Pitch: 12 Threads Per Inch (Fine)


• Material: Industrial Grade Steel


• Function: Valve Protection Cap Attachment