Pipeline Shim Dimensions & Thickness Guide: How to Size Shims for Pipe Supports
Selecting the correct shim dimensions is one of the most important steps in pipeline construction and pipe support installation. Shim thickness, width, and length must be precisely matched to the gap between the pipe (or pipe shoe) and the support structure to ensure proper load distribution, alignment, and long-term structural integrity.
This guide covers standard shim thicknesses used in the oil and gas industry, how to measure and calculate shim requirements, and best practices for documenting shim dimensions at each pipe support location.
Standard Shim Thicknesses
Pipeline shims are available in a range of standard thicknesses. The most commonly used thicknesses in oil and gas construction follow imperial and metric standards:
| Imperial (inches) | Metric (mm) | Common Use |
|---|---|---|
| 1/16" (0.0625") | 1.6 mm | Fine adjustment, precision alignment |
| 1/8" (0.125") | 3.2 mm | Standard gap fill, most common thickness |
| 3/16" (0.1875") | 4.8 mm | Moderate gap fill |
| 1/4" (0.250") | 6.4 mm | Large gap fill, heavy pipe supports |
| 3/8" (0.375") | 9.5 mm | Major elevation correction |
| 1/2" (0.500") | 12.7 mm | Large bore pipe supports, shim blocks |
| 3/4" (0.750") | 19.1 mm | Heavy-duty applications |
| 1" (1.000") | 25.4 mm | Shim blocks, adjustable supports |
How to Measure Shim Gap at Pipe Supports
Accurate measurement of the gap between the pipe and support is essential for selecting the right shim dimensions. Here is the standard process used by pipeline field professionals:
- Position the pipe – Set the pipe on the support structure in its final location
- Measure the gap – Use feeler gauges, taper gauges, or a steel rule to measure the distance between the bottom of the pipe shoe and the top of the support
- Check at multiple points – Measure at both edges and the center of the support to identify any angular gap
- Account for tolerances – Consider the design elevation tolerance specified in the project drawings
- Record the measurement – Document the gap dimension, location, and support number
Shim Width and Length Sizing
While thickness gets the most attention, the width and length of shims are equally important for proper load distribution:
- Width should match or slightly exceed the width of the pipe shoe or bearing surface
- Length should cover the full bearing area of the pipe on the support
- Shims should never overhang the support edge, as this creates a cantilever loading condition
- For round pipe on saddle supports, shim dimensions must conform to the saddle contact area
Typical Shim Dimensions by Pipe Size
| Pipe Size (NPS) | Typical Shoe Width | Recommended Shim Width | Shim Length |
|---|---|---|---|
| 2" - 4" | 3" - 4" | 3" - 4" | 4" - 6" |
| 6" - 8" | 4" - 6" | 4" - 6" | 6" - 8" |
| 10" - 14" | 6" - 8" | 6" - 8" | 8" - 12" |
| 16" - 24" | 8" - 12" | 8" - 12" | 12" - 16" |
| 26" - 48" | 12" - 18" | 12" - 18" | 16" - 24" |
Shim Stacking Rules
When the required gap exceeds the thickness of a single shim, stacking is necessary. Follow these industry best practices:
- Minimize the number of shims in a stack – use the fewest possible
- Maximum recommended stack: 3 to 4 shims (check project specifications)
- If more than 4 shims are needed, consider using a machined shim plate or shim block instead
- All shims in a stack should be the same width and length
- Tack weld or strap the stack together to prevent individual shims from sliding out during operation
Recording Shim Dimensions in the Field
Every shim installation should be documented with the following data points:
- Support number / location identifier
- Shim thickness (individual and total stack height)
- Number of shims in the stack
- Shim material and grade
- Shim width and length
- Direction of any tapered shims
- Date of installation and installer name
Record Shim Dimensions Digitally with ShimSheet
Stop using paper logs and spreadsheets for shim data. ShimSheet lets you record shim dimensions, thickness, material, and support location directly from your phone or tablet in the field. Generate professional PDF reports instantly.
Try ShimSheet FreeMetric vs Imperial Shim Dimensions
Projects in Canada, the Middle East, and many international locations use metric dimensions, while US projects typically use imperial. Always confirm which measurement system the project specification requires, and ensure your shim records match. Converting between systems is a common source of errors – using a digital tool that supports both unit systems eliminates this risk.
When to Use Shim Blocks vs Flat Shims
For gaps exceeding 1 inch (25 mm), flat shim stacking becomes impractical. In these cases, shim blocks or machined shim plates are the preferred solution. Shim blocks provide:
- Greater load-bearing capacity for heavy pipe
- Built-in adjustment mechanisms (threaded rods)
- Better resistance to vibration-induced displacement
- Cleaner documentation since each block is a single unit
Conclusion
Getting shim dimensions right is fundamental to pipeline construction quality. From selecting the correct thickness to properly sizing width and length for the support, every dimension matters. With ShimSheet, you can record and track all shim dimension data digitally, ensuring accurate documentation and professional reporting for every pipe support on your project.