Bend-a-Flex™ Tube & Shell Coolers

Bend-a-Flex™ Equipped Tube & Shell Coolers

When 1.6M kM Durability in > 9L engines is required

Among emissions-related components, EGR (Exhaust Gas Recirculation) coolers are some of the most complex and historically unreliable subsystems of a modern engine. Senior Flexonics saw customers struggling with these products and moved quickly to adapt existing technologies and expertise to provide a solution. Central to the design of these coolers was the use of thermal compensating tubes utilizing Bend-a-Flex™ tube technology.



When evaluating EGR cooler durability, it is crucial to understand the different loading mechanisms and their causes within a general loading category – primarily thermal cycling. Thermal loading of EGR coolers falls into two levels that are typically referred to as thermal fatigue (high cycle) and thermal shock (low cycle).

High-Cycle Thermal Fatigue

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Low-Cycle Thermal Shock

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The Bend-A-Flex™ Solution

These situations are where the base architecture of Bend-a-Flex™ sets itself apart from the competition. Developed specifically for the truck’s heavy duty engine, our cooler replaces the OEM insert with our proprietary flexible tube technology. Called Bend-a-Flex™, our proven system is designed to withstand non-standard coolant events that can occur at any time. While stiff-tubed coolers can fail within seconds of coolant loss, Senior Flexonics’ EGR coolers have survived events such as these thousands of times. Both rig and field-testing have shown nearly unlimited resistance to any cooling system issues the engine is capable of generating. One test shut off the water flow to the cooler and allowed it to boil dry under continuous hot gas flow. Coolant flow was then restored and subsequently shut off again, replicating an absolute worst-case field scenario. Competitor after competitors’ coolers failed on this test within a handful of cycles; Senior Flexonics’ EGR coolers were pulled off the test after thousands of cycles without any issue.

Other EGR cooler manufacturers have attempted to replicate these results with macro-compensating features such as floating cores or convoluted outer shells. These strategies, however, are fundamentally flawed because cooling systems do not see issues on a macro scale. Any of the above issues will result in non-uniform expansion of the gas tubes (typically starting with the upper tubes) rendering the macro-compensating feature useless. By utilizing individual flexible tubes, every passage within the tube array has micro-compensating abilities and accommodates thermal expansion independently of the rest of the tube bundle.

This level of thermal shock resistance sets the Bend-a-Flex™ equipped EGR Coolers far apart from the rest of the competition.

Bend-a-Flex™ Features:

  • Flexibility of inner gas and outer coolant tube reduce engine assembly stresses


  • Automotive
  • Diesel
  • Land Vehicles


  • Pre cooling of EGR coolers
  • Intermediate / additional cooling of Diesel exhaust systems

Publications/case studies featuring our EGR Coolers:

Strength through flexibility – Engine Technology International Sept 2012