The Size Problem

Everyone knows large flanges require large gaskets but these large sizes also pose a unique sealing problem. How big can you go?

Spiral Wound Gaskets (SWGs) are extremely fragile in large diameters and can even buckle while handling and transportation. Hence design engineers ignore the practical aspect of the Spiral Wound Gaskets limitations. Adding a groove or a male-female joint might reduce the dependency on a Gasket but the resultant SWG (only windings) is even more fragile and delicate to handle.

Experienced maintenance engineers therefore prefer larger Gaskets made from softer material like CNAF, Graphite and PTFE. These materials are able to handle uneven surface stress and flange waviness that accompanies such large Gaskets.

These Gaskets are cut from Sheets of a specific length hence they are limited in diameter. What happens when a Gasket diameter is more than the width of the Sheet?

The standard Length X Width measurement for reputed Raw Material manufacturers is usually in Square Shaped. This is because manufacturing a circle from a square sheet generates least amount of scrap for a consumer.

For example: Donit Tesnit, one of Europe's largest Sheet Manufacturer has a standard size of 1500mm X 1500mm or 2.25 Sq Mtrs.

But what happens when you require a Gasket of Diameter above 1500mm?

The answer: Dovetail Joints.

Dovetail Joints are special arcs with precise tolerances that can be used to form an eventual bigger Gasket onsite itself. Image them as jigsaw Puzzles where each arc is carefully manufactured using a computer controlled cutting machine.

But how will joints in Gaskets work?

Obviously joints in Metallic materials or semi-Metallic materials offer leakage paths but these Soft materials are different. They have volumetric expansion and when sufficient surface stress is applied, they actually expand across the seam and seal that joint.

Dovetail Joints are favoured because their value addition is enormous.

1. Less scrap generation. They are no longer dependent upon sheet manufacturers holding a monopoly because they have a 2000mm Width or a 3000mm Width standard sheet size.
2. Economical. Dovetail Joints efficiently consume a Sheet and hence offer most cost savings since cutting cost is usually only 10% of a Gasket manufacturing cost.
3. Transportation. These are shipped in small packages to be manufactured onsite itself which means reduction in transportation and logistics. Anyone who has procuring Spiral Wound or Heat Exchanger Gaskets in large sizes will know about the cost of transportation when compared to the actual product.

4. Additional reinforcement: In certain cases you can add a reinforcement to your Gaskets onsite itself to add more rigidity.

Your Gasket Manufacturer should be able to provide you with the required torque value required to ensure sealing of these Large Gaskets.

We are a partner for Donit Tesnit, Slovenia in India and we recently manufactured Doniflon? (Modified PTFE) Gaskets thanks to a technology transfer of PTFE Welding technology from Donit Tesnit, Europe.

Consult PILOT Gaskets and Engineers for help with Large Gaskets and the most value added solution for your equipment.

Email: [email protected] or Web: www.pilotgaskets.com or Ph: +91 8080890022

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