Spi 34-446-5 Threaded Pipe Ring 1/4-18 Npt L1 Tool Steel

Product Description

The SPI 34-446-5 is a Class L1 threaded pipe ring gauge manufactured from tool steel for precision thread inspection of 1/4-18 NPT tapered pipe threads. This ring gauge is used to verify that external NPT threads meet dimensional and taper tolerances required for leak-free pipe and fitting assemblies. It comes with NIST traceability certification, confirming calibration to national measurement standards. Plumbers, pipefitters, and quality control technicians use this gauge to check threaded connections on pipe, fittings, and valves before assembly, reducing the risk of leaks or cross-threading at the joint.

This gauge is suited for applications in residential and commercial plumbing, HVAC refrigerant piping, gas distribution, and industrial pipe fabrication where NPT thread quality must be verified. Class L1 classification designates it as a working gauge for production and field inspection use, appropriate for verifying threads on carbon steel, copper, and brass pipe and fittings with a 1/4-18 NPT thread form. It is particularly useful in shops or field settings where thread acceptance needs to be documented against NIST-traceable standards.

Key Features

• Class L1 working gauge classification for production and field thread inspection
• Thread size 1/4-18 NPT for tapered pipe thread verification
• Tool steel construction for durability and wear resistance during repeated use
• Includes NIST traceability certification for documented calibration compliance
• Single-piece package for individual gauge inventory and calibration tracking

Compatibility

Designed for inspection of external 1/4-18 NPT tapered pipe threads on pipe, fittings, and threaded components conforming to the NPT thread standard.

Installation Notes

Thread ring gauges are precision instruments and should be handled and stored carefully to prevent damage to the gauging surface. Ensure all threads being inspected are clean and free of burrs, chips, or debris before gauging. Gauge engagement should be performed by hand without tools or forced rotation. Periodic recalibration against NIST-traceable masters is recommended to maintain measurement integrity.