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Tech Talk
An in-line pressure balanced expansion joint with a heating system to maintain the bellows temperature in a specific range .
Movement testing of expansion joints follows a structured procedure to simulate the mechanical and thermal loads expected in real-world operation .
Step 2 : Assemble testing equipment and tools The ‘ setup ’ of a movement test involves attaching a dynamometer to a device system that exerts force on the expansion joint . During the test , the expansion joint ’ s movement and load at specific movement or angles are recorded . This setup allows for precise measurement of movement , ensuring alignment with design calculations . For accurate testing , the following key equipment is typically used :
• Dynamometer : Also referred to as an electronic scale , this measures the applied force on the expansion joint .
• Pulley system : Used to apply a controlled load .
• Angle / Movement gauge : This helps measure the movement of the expansion joint .
• Pressure source : A means of pressurizing the joint ( if testing under simulated operating pressure ).
Step 3 : Conduct the movement test
• Apply controlled load / Inside pressure :
• Begin by applying a small amount of force to the joint and slowly increase it .
• Measure the force at each degree of linear or angular displacement ( e . g ., 1 °, 2 °, 3 °) to record the response of the joint .
• Technicians compare these results with calculated spring rates to ensure that the joint ’ s
performance aligns with design expectations . Testing may also include recording frictional load changes due to pressure , offering insight into the durability and performance of the joint under pressurized conditions .
• Measure angular displacement :
• Using the gauge or scale , the displacement of the expansion joint is measured and recorded . This data helps verify if the joint meets the design ’ s movement specifications .
• Check for consistency :
• With some expansion joint manufacturers , such as Teadit , the test results are compared with historical data and theoretical calculations . Customers receive a comprehensive report detailing each joint ’ s performance , ensuring the components meet the required specifications . This test confirms that the joint ’ s spring rate is within acceptable parameters and aligns with design specifications .
It is important to note that movement tests on expansion joints installed in FCC units should be performed under pressure to account for operational loads .
Step 4 : Record and analyze data Data collected during the movement test — including force , applied movement , and pressure readings — provide essential insights . It is always advised to follow prescribed best practices . For example , Teadit follows the outlined process :
• Verify against design calculations : Confirm that the measured spring rate and load capacities align with design calculations . www . heat-exchanger-world . com Heat Exchanger World February 2025
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