Case Studies

Background

Leakage was occurring at the heat exchanger flange bolted joints in a chemical plant. Although gasket replacement was carried out during scheduled shutdown maintenance, hot bolting was still required during start-up, meaning scaffolding could not be dismantled or removed — this had become a problem. In addition, since hot bolting itself involves safety risks, finding a better approach was a key challenge.

Root Cause

The likely cause is that, due to thermal cycling and the presence of both low-temperature and high-temperature zones on the same flange surface, the gasket seating stress required to prevent internal fluid leakage cannot be kept uniformly consistent at all times.

Leakage occurs because the gasket’s recovery (resilience) cannot keep up with the thermal cycling at the flange bolted joint.

Recommended Product

Chesterton 5500 Flange Disc Spring.

Benefits

・ [Automatic preload management]

After bolt tightening, the disc springs suppress the drop in gasket seating stress caused by differences in thermal expansion and contraction between the flange and bolts. By maintaining proper bolt preload at all times, they keep the required gasket pressure applied and prevent leakage paths from forming.

・ [No hot bolting required]

Thanks to the disc springs’ automatic preload management function, hazardous hot bolting work is no longer necessary.

Disc springs with a spring function that maintain bolt axial force (preload).

Customer Report

There was no need to perform hot bolting during start-up, and no initial leakage was observed. As a result, the scaffolding around the heat exchanger could be dismantled before commissioning.

In addition, no flange leakage occurred from the shutdown maintenance through to the next scheduled maintenance, allowing safe and stable operation to continue.

They also achieved significant cost reductions in hot bolting work, scaffolding removal as a separate task, and maintenance costs associated with leakage.

Disc springs after bolt tightening.

Chesterton® is a world leader in helping process industry companies and manufacturers improve the reliability and efficiency of their rotating, stationary, and fluid power equipment platforms. We are known across a wide range of industries for our award-winning pump and valve sealing solutions, applications expertise, equipment maintenance and wear-prevention products, and knowledgeable hands-on local service. Chesterton product range includes mechanical seals, packing and gaskets, industrial lubricants and coatings.

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APAC0112. Issued 11/2025

Technical data reflects results of laboratory tests and is intended to indicate general characteristics only. A.W. Chesterton Company disclaims all warranties expressed or implied, including warranties of merchantability and fitness for a particular purpose. Liability, if any, is limited to product replacement only. Any images contained herein are for general illustrative or aesthetic purposes only and are not intended to convey any instructional, safety, handling, or usage information or advice respecting any product or equipment. Please refer to relevant Safety Data Sheets, Product Data Sheets, and/or Product Labels for safe use, storage, handling, and disposal of products, or consult with your local Chesterton sales representative.