Shim Packs & Shim Stacks Guide for Pipeline Construction

Shim packs and shim stacks are used extensively in pipeline construction to achieve precise alignment and elevation adjustments at pipe supports. Understanding how to properly assemble, install, and document shim stacks is essential for quality pipeline work.

What Are Shim Packs?

A shim pack is a pre-assembled set of shims in various thicknesses, bundled together for field use. Shim packs allow crews to quickly select the right combination of shim thicknesses to fill any gap. Common shim pack contents include thicknesses from 0.001 inch to 0.125 inch in incremental sizes.

What Is a Shim Stack?

A shim stack is multiple individual shims layered on top of each other at a single pipe support location. When a single shim cannot provide the exact thickness needed, a stack of two or more shims is used to achieve the correct total thickness.

Shim Stacking Rules and Best Practices

1. Limit shim stacks to 3-4 individual shims maximum
2. All shims in a stack must be the same width and length
3. Place the thickest shim at the bottom of the stack
4. Ensure all shims in the stack are the same material grade
5. Tack weld or band shim stacks together to prevent separation
6. Document every individual shim in the stack
7. If total stack exceeds 1/2 inch, consider machined spacers instead

Types of Shim Packs

• Peelable shim packs — laminated layers you peel to exact thickness
• Assorted shim kits — multiple loose shims in various thicknesses
• Precision shim sets — tight-tolerance shims for critical applications
• Custom shim packs — project-specific sizes and materials