Shim Gap Measurement Tools: Feeler Gauges, Taper Gauges & Digital Methods

Why Accurate Gap Measurement Matters

Before installing shims at a pipe support, you need to know the exact gap between the pipe or pipe shoe and the structural steel below it. An inaccurate measurement means the wrong shim thickness, which leads to improper pipe elevation, stress on the piping system, and potential rework.

The right measurement tool depends on the gap size, the accessibility of the support point, and the precision required by the project specifications.

Feeler Gauges for Shim Gap Measurement

Feeler gauges are the most common tool for measuring small gaps at pipe supports. A feeler gauge set consists of thin metal blades of known thicknesses that are inserted into the gap to determine its size.

When to Use Feeler Gauges

• Gaps up to approximately 1 inch (25 mm)
• Situations requiring high precision (thousandths of an inch)
• Verifying shim pack thickness after installation
• Checking for uniform contact across the width of a support

Feeler Gauge Best Practices

• Always use calibrated gauge sets and check for damaged or bent blades
• Insert the blade gently without forcing it, as this can give a false reading
• Measure at multiple points across the width of the support to check for taper
• Record the measurement immediately using a digital tool like ShimSheet

Taper Gauges for Larger Gaps

Taper gauges (also called wedge gauges or gap gauges) are wedge-shaped tools that slide into a gap. The gauge is marked with graduated measurements along its length, so you read the gap size at the point where the gauge stops.

Advantages of Taper Gauges

• Quick single-reading measurement for gaps from 1/16 inch to 1 inch or more
• Durable and easy to use in rough field conditions
• No assembly required unlike feeler gauge stacking
• Available in both imperial and metric graduations

Steel Rules and Measuring Tapes

For larger gaps where precision to the nearest 1/16 inch is sufficient, a steel rule or measuring tape is the simplest tool. This method is common for initial rough measurements before selecting shim stock, with finer tools used for final verification.

Digital and Laser Measurement Tools

Digital calipers and laser distance meters are increasingly used on pipeline projects where high precision and digital record-keeping are priorities.

Recording Shim Measurements Digitally

No matter which measurement tool you use, the data is only valuable if it is recorded accurately and accessibly. Writing measurements on paper in the field introduces transcription errors and risks data loss.

ShimSheet lets you record shim dimensions directly on your phone at the pipe support. Each measurement is tied to a specific support point in your project, timestamped, and synced to the cloud. When it is time to generate a report, all your measurements are already organized and ready.

Choosing the Right Tool for the Job

Frequently Asked Questions

What is the best tool for measuring shim gaps?

Feeler gauges are best for small, precise gaps under half an inch. Taper gauges work well for quick measurements of larger gaps. Digital calipers offer the highest precision for any gap size.

How do I record shim measurements in the field?

Use a digital shim tracking app like ShimSheet to record measurements on your phone directly at the pipe support. This eliminates paper records and transcription errors.

Do I need to measure gaps at every pipe support?

Yes. Every pipe support that requires shimming should have its gap measured and recorded. Even small variations in gap size affect pipe elevation and system alignment.