Precision Thread Ring Gauge - NPT 3/8 x 18

• Verify external threads for acceptance during in process inspection and final inspection.
• Separate functional threads from nonconforming threads using GO and NO GO criteria.
• Use in toolrooms, calibration areas, and quality control for quick pass fail checks.
• Keep the thread clean and lightly oiled to protect the gauge and to improve repeatability.
• Process: manual driving or assisted driving depending on your holder and machine setup.
• Use: thread cutting, re tapping, and thread cleaning depending on condition.

Note Handle the gauge as a measuring tool, store it protected, and avoid impact and corrosion.

• Fast pass fail check without numerical measurement effort.
• GO and NO GO logic supports clear acceptance decisions.
• Tolerance class in the designation helps match the required fit concept.
• Suitable for incoming inspection and in process checks when handled consistently.

• Does not provide deviation values, it only indicates functional acceptance or rejection.
• Not suitable for threads with heavy damage or burrs, since that can cause false results.

1. Clean the external thread and remove burrs before inspection.
2. Clean the gauge thread and apply a light protective oil film.
3. Start the gauge square to the thread and turn by hand only.
4. For GO checks, verify that the gauge passes with low force over the specified inspection length.
5. For NO GO checks, verify that the gauge does not pass beyond the allowed engagement.
6. Record the result and store the gauge protected from corrosion and impact.

• 1 piece Precision Thread Ring Gauge - NPT 3/8 x 18

• Product type: Thread ring gauge
• Thread system: NPT

What is the difference between GO and NO GO checks

GO checks confirm functional assembly within the allowed minimum material condition, while NO GO checks prevent oversize threads that would reduce engagement. You use both checks to get a clear accept reject decision without measuring values.

How do you match the gauge to a thread specification

Match the thread system, series, and tolerance class from the drawing to the gauge designation. Do not mix similar looking inch and metric systems during inspection.

Should you apply force when you screw on a ring gauge

Turn the gauge by hand only and use light, steady torque. If the gauge binds early, clean the thread and check for burrs before you interpret the result.

How do you keep inspection results repeatable

Keep both thread and gauge clean, apply a light oil film, and check at stable temperature where possible. Use consistent handling and avoid impact that can damage the gauge flanks.

How do you store and protect the gauge

Wipe the gauge after use, apply corrosion protection, and store it in its protective packaging. Keep it away from chips, coolant residues, and vibration.

Where can you find catalog information for thread gauges and inspection

VG 23 catalog as PDF

Can you use the gauge on threads with coating or plating

Coatings can change effective thread size and surface friction. Verify the specification for the coated thread and use the correct tolerance class, and keep the gauge protected from abrasive contamination.