Link Seal Calculator

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function calculateLinkSeal() { var pipeOD = parseFloat(document.getElementById('pipeOD').value); var openingID = parseFloat(document.getElementById('openingID').value); var unit = document.getElementById('calcUnit').value; var resultDiv = document.getElementById('sealResults'); if (isNaN(pipeOD) || isNaN(openingID) || pipeOD <= 0 || openingID = openingID) { alert("Opening ID must be larger than Pipe OD to allow for a seal."); return; } var annularSpace = (openingID – pipeOD) / 2; var model = ""; var linkPitch = 0; // Length of one link in inches // Standard Link-Seal Model Mapping (Approximated based on radial gap ranges in inches) var gapInches = unit === 'mm' ? annularSpace / 25.4 : annularSpace; if (gapInches >= 0.43 && gapInches 0.55 && gapInches 0.70 && gapInches 0.82 && gapInches 1.10 && gapInches 1.35 && gapInches 1.55 && gapInches 1.85 && gapInches 2.20 && gapInches 0) { // Circumference at the center of the seal var meanDiameter = (openingID + pipeOD) / 2; var meanCircumference = Math.PI * meanDiameter; // If units are mm, convert pitch to mm for the calculation var effectivePitch = unit === 'mm' ? linkPitch * 25.4 : linkPitch; links = Math.ceil(meanCircumference / effectivePitch); } document.getElementById('resAnnular').innerHTML = annularSpace.toFixed(3) + " " + unit; document.getElementById('resModel').innerHTML = model; document.getElementById('resCount').innerHTML = links > 0 ? links + " links" : "N/A"; resultDiv.style.display = 'block'; }

Understanding Link-Seal Calculations for Pipe Penetrations

A Link-Seal® modular seal is the industry standard for creating a permanent, hydrostatic seal for pipes passing through walls, floors, or casings. Unlike grout or caulk, these mechanical seals use interconnected rubber links that expand when tightened to create a gas and water-tight pressure seal.

How to Use the Link-Seal Calculator

To determine the correct size and quantity of links for your project, you need two primary measurements:

  • Pipe Outside Diameter (OD): This is the actual outside measurement of the pipe, not the nominal pipe size. For example, a 6-inch Schedule 40 steel pipe has an actual OD of 6.625 inches.
  • Wall Opening or Casing ID: This is the diameter of the core-drilled hole or the inside diameter of the wall sleeve/casing pipe.

The Science of Sizing: The Annular Space

The most critical factor in link-seal selection is the Annular Space. This is the radial distance between the pipe and the opening. The formula is:

Annular Space = (Opening ID – Pipe OD) / 2

Each Link-Seal model (such as LS-300 or LS-400) is designed to expand within a specific annular range. If the gap is too small, the seal won't fit; if the gap is too large, the seal won't expand enough to create a pressure-tight bond.

Example Calculation

Imagine you are installing a 10-inch Ductile Iron pipe through a 14-inch core-drilled hole:

  1. Pipe OD: 11.10 inches
  2. Opening ID: 14.00 inches
  3. Annular Space: (14.00 – 11.10) / 2 = 1.45 inches
  4. Model Selection: Based on the 1.45″ gap, the LS-475 model is typically selected as its range accommodates gaps from 1.35″ to 1.55″.
  5. Quantity: The calculator uses the mean circumference to determine that approximately 14 links are required to form a complete belt around this pipe size.

Important Engineering Considerations

While this calculator provides a highly accurate estimate, always consider the following environmental factors:

  • Material Type: EPDM (Black) is standard for water; Nitrile (Green) is used for fuels and oils; Silicone (Grey) is used for high-temperature applications.
  • Hardware: Use 316 Stainless Steel bolts for corrosive environments or wastewater applications.
  • Centering: For very heavy pipes or large diameters, ensure the pipe is properly supported so the seal is not bearing the weight of the pipe.

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