Spi 34-437-4 Pipe Thread Plug Gage 1/2-14 Npt Class L-1

Product Description

The SPI 34-437-4 is a tapered pipe thread plug gage used to verify the accuracy of internal NPT pipe threads to Class L-1 tolerance. It is a single-end gage fitted with a Handle Size 4 and is designed for use with 1/2-14 NPT thread forms. This gage checks that machined or tapped internal pipe threads conform to ANSI B1.20.1 dimensional requirements, ensuring pressure-tight, leak-free joints in fluid and gas piping systems. It ships with a NIST Traceability Certificate, making it suitable for use in calibrated inspection environments. Machinists, pipefitters, and quality control technicians rely on this tool for production and acceptance inspection.

This gage applies to any manufacturing or service environment where 1/2-14 NPT internal threads must be verified before assembly. Typical applications include inspection of pipe fittings, valve bodies, manifolds, hydraulic blocks, and plumbing components. It is commonly used in plumbing, HVAC, industrial piping, and fluid power shops where threaded joint integrity is a critical quality checkpoint. The included NIST Traceability Certificate supports documented quality systems and calibration audit requirements.

Key Features

• Tapered NPT thread form per ANSI B1.20.1 and NIST standards
• Class L-1 tolerance for standard pipe thread acceptance inspection
• 1/2-14 thread size for common half-inch pipe connections
• Single-end design with Handle Size 4 for secure, ergonomic use
• Includes NIST Traceability Certificate for calibrated inspection environments
• Weighs 1 pound for easy bench or field handling

Compatibility

Designed for inspection of 1/2-14 NPT internal tapered pipe threads in fittings, valve bodies, and piping components manufactured to ANSI B1.20.1.

Installation Notes

This gage is a precision inspection tool and should be handled by qualified machinists or QC technicians familiar with thread gage procedures. Store in a protective case when not in use to prevent damage to thread flanks. Do not force the gage into an undertapped hole, as this can damage the gage and produce inaccurate readings. Reference ANSI B1.20.1 and your gage manufacturer procedure for correct engagement and pass-fail criteria.