Struggling to Find the Right Spray Speed for I.D. Coating?

If you’ve ever had trouble figuring out the correct spray speed when coating the internal diameter (I.D.) of a pipe, you’re not alone. Most people resort to repeated trial runs to determine how fast to pull back the coating tool. The good news is, with just a couple of simple calculations—and some reference marks on your hoses—you can achieve a consistent coating every time.

Step 1: Determine Your Coating Flow Rate

Before running the calculations, you’ll need to know the flow rate of your coating tool. Use a measuring beaker and a timer: spray for 30 seconds and record the total ounces collected. Important: be sure to turn off the atomization air while doing this test.

Step 2: Apply the Calculation

With your flow rate in hand, you can now calculate the ideal travel speed of your coating tool. You’ll need the following inputs:

• Internal diameter of the pipe
• Desired dry film thickness
• Coating percent solids
• Measured flow volume (from your 30-second test)
• Flow time (30 seconds)

Using these values, you can determine how long it should take the tool to move 1 lineal foot inside the pipe. You can either calculate this manually with the formula provided above, or simply use our I.D. Coating Speed Calculator for a quick answer.

👉 With this method, you’ll save time, reduce wasted coating, and achieve a reliable, uniform finish without endless trial and error.