Link-Seal Modular Seals Sizing Procedure 2 for Pipe Sizes that Do Not Appear in Charts

Method 2 - Link-Seal Modular Seal Sizing

If your pipe size does not appear in the charts for standard pipe sizes, use the following method to select the correct Link-Seal modular seal for your application.

  1. Calculate the annular space. The annular space is half the difference between the actual pipe O.D. and the actual wall I.D. opening diameter. Use the following formula:

Annular Space = (Wall Opening I.D. - Actual Pipe O.D.) / 2

  1. From the charts below, select the size closest to the annular space calculated in step 1. You have selected the correct size Link-Seal modular seal if....the free state thickness is less than the annular space...and the expanded state thickness is greater than the annular space.


  1. Calculate the number of links required to fit around the pipe and seal the annular space.

A. Determine the bolt circle for your Link-Seal modular seal assembly by using the following formula:

Bolt Circle = (Wall Opening I.D. + Pipe Diameter O.D.) / 2

B. Find the Link-Seal modular seal chord length (Column 4) and use the following formula to determine required number of links per Link-Seal modular seal assembly.

Links Per Seal = (Bolt Circle x 3.14) / Chord Length

The result must be rounded down to the next whole number. The figures are accurate if the calculation results in 13 or more links per belt. If the results are fewer than 13 links verify using the linked verification charts below.

Verification charts for Link-Seal LS-200 through LS-360

Verification charts for Link-Seal LS-400 through LS-600



Wall Opening I.D. = 12”
Actual Pipe O.D. = 9.05”

Calculate the annular Space as (12 - 9.05) / 2 = 1.475

Select the Link-Seal modular seal size closest to the annular space. LS-400 is chosen from the chart, because 1.475” falls between 1.43 and 1.81 (the free state and expanded state thickness).

Determine the number of links for a complete assembly:

Bolt circle = (12 + 9.05) / 2 = 10.525
Chord length for LS-400 = 3.635"
Links per seal = (10.525 x 3.14) / 3.625 = 9.12
Round down links per seal to 9.

Since the final calculation results in fewer than 13 links, it is advisable to verify the accuracy of the calculation by using the verification charts.