Spi 34-440-8 Pipe Thread Plug Gage Npt Class L-1

Product Description

The SPI 34-440-8 is a tapered pipe thread plug gage designed to verify internal NPT (National Pipe Taper) threads to ANSI B1.20.1 standards. Sized for 1-1/4-11-1/2 thread form and rated to Class L-1 tolerance, this single-end gage gives machinists, pipefitters, and quality-control technicians a reliable go/no-go reference for checking thread engagement and taper conformance. Each unit ships with a NIST Traceability Certificate, making it suitable for calibrated measurement environments where documented traceability is required. Handle Size 5 provides a secure, ergonomic grip during inspection.

This gage is used in fabrication shops, pipe assembly facilities, and manufacturing quality departments wherever NPT internal threads must be verified before assembly. Typical applications include inspection of pipe fittings, valve bodies, manifolds, and any threaded pipe connection requiring confirmed taper and pitch compliance. The Class L-1 designation corresponds to the standard engagement length check per ANSI B1.20.1, which is the most common acceptance criterion for NPT pipe threads in plumbing, HVAC, and industrial piping systems.

Key Features

• Tapered NPT thread form per ANSI B1.20.1 — verifies 1-1/4-11-1/2 internal pipe threads
• Class L-1 tolerance rating for standard engagement length acceptance
• Single-end configuration with Handle Size 5 for controlled hand inspection
• Includes NIST Traceability Certificate for use in calibrated QC environments
• Weighs 1 pound — compact enough for bench or field inspection use

Compatibility

Designed for inspection of internal NPT tapered pipe threads sized 1-1/4-11-1/2, conforming to ANSI B1.20.1 and NIST standards. Suitable for use anywhere Class L-1 thread verification is required on NPT-threaded pipe fittings, valve bodies, or similar components.

Installation Notes

Thread plug gages are precision inspection tools and should be handled and stored carefully to avoid damage to the gage threads. Apply a light thread lubricant when gaging to reduce wear and ensure accurate readings. Do not force the gage into the workpiece thread — engagement should proceed smoothly by hand torque only. Verify the gage itself is within calibration before use, referencing the included NIST Traceability Certificate for documentation.