Thermal shock is a phenomenon that often goes unnoticed but can potentially devastate various industrial and domestic applications.

In this article, learn more about thermal shock, highlighting its significance and how it can be effectively prevented.

What is thermal shock?

Thermal shock refers to the response of a material or system to a sudden and significant change in temperature, generating internal stresses that can result in fractures. 

It can occur in various situations – from ice breaking when exposed to a hot drink to parts of industrial machinery shattering due to temperature fluctuations.

The key to thermal shock lies in the differences within the thermal expansion of the materials. When heated or cooled rapidly, their components can expand or contract at different rates, leading to internal stresses and eventual fracturing.

One substantial detail to keep in mind is a given material's thermal resistance, which is essential in high temperature environments since it refers to its ability to withstand heat flows or temperature transfers.

Find out what factors influence this phenomenon below.

Which factors contribute to thermal shock?

1. Temperature. Each material has its range of thermal shock resistance. For example, it may withstand low temperatures but crack when exposed to higher ones.
   
2. Fluctuation velocity. A sudden temperature change will cause stress, causing fracturing or cracking (as with an ice cube dropped into a hot drink). However, an incremental temperature transition favors adaptation, preventing early or sudden damage.
   
3. Chemical composition. There are two types of materials: those with an ordered crystalline structure and those composed of amorphous configurations. 
   
   The former tend to be more resistant to thermal shock due to the regular arrangement of their atoms. For instance, ceramic fiber can withstand high temperatures due to its alumina and silica composition.
   
   
   
   In NUTEC’s product catalog, you can find the following compositions:
   
   Ceramic fiber. With an alumina and silica composition, such compounds can achieve high thermal insulation capacity with a maximum use temperature of 2300⁰F (1260⁰C). Furthermore, adding zirconia can increase the operating temperature to 2600°F (1425°C).
   
   Low Biopersistence Fiber (LBP). Also known as soluble fiber, it is composed of calcium, silica, and magnesium, withstanding temperatures of 2200°F (1200°C).
   
   Polycrystalline fiber. Formed of mullite or high alumina fiber, it can withstand temperatures of 3000°F (1650°C).
   
   Remember that the ideal composition depends on the specific needs of each industrial process.
   
   
   
4. Thickness. Thinner materials tend to be more resistant to thermal shock as they can effectively disperse heat. On the other hand, thicker materials tend to retain heat at an exact point, generating stress and fracture.
   
5. Heat treatment. Some processes transform the integrity of the material, for example, annealing. As it is a process that adds temperature, it can change the product's chemical structure from ordered to amorphous.

What are the consequences of thermal shock?

Impact on materials and components

Thermal shock can have severe consequences on materials and components, including the following:

• Fragilization. Increases the probability of fracture.
  
• Fracture. It can lead to cracks and ruptures of critical components, resulting in costly repairs or outright replacements.
  
• Accelerated corrosion. Thermal shock can accelerate deterioration as damaged surfaces are more susceptible to environmental effects.

Impact on operational efficiency

In addition to physical damage, thermal shock can also have an adverse effect in the following ways:

• Energy inefficiency. Thermal shock in heating and cooling systems can cause increased energy consumption due to temperature fluctuation.
  
• Loss of productivity. In industrial environments, downtime due to thermal shock maintenance can result in significant productivity losses.

How to prevent thermal shock?

Smart design

Facilitating simulation for both redesigning the industrial process and applying thermal insulation solutions is essential. Likewise, we advise considering the following factors:

• Soft temperature gradients. Avoid designs that generate abrupt temperature gradients to extend the equipment's and the insulation's life. Designing systems that distribute heat or cold evenly is crucial. 
  
• Compatible materials. Choose products adapted to the needs of each particular industrial process. Selecting a product that only just copes with the operating temperature range is not a good approach.
  

At NUTEC, you have the engineering team with the experience you need to select the appropriate insulation solution for your industry.

Temperature control and regulation

For effective heat management in controlled processes, it is necessary to have the two following aspects in check:

• Heating and cooling ramps. These refer to the rates at which the temperature of a system or object is gradually increased or decreased over a specific period. Applying these concepts translates to an extended useful life of the equipment.
  
• Thermometers. Currently, more and more access to automated controls can give a real-time temperature reading throughout the process. Additionally, they can send alerts in case of any anomaly.

Thermal shock by industry sector

• Aerospace industry. Airplanes and spacecraft operate in extreme environments. Therefore, engines and control systems must be protected to withstand sudden temperature changes during takeoff and landing, especially when traveling between different climatic regions.
  
• Electronics industry. Electronic components generate heat during operation. The materials that cover cables and parts must be heat resistant to avoid failures and ensure optimal performance.
  
• Automotive industry. Given components' exposure to high temperatures during combustion – from the engine to the exhaust systems – heat insulators contribute to avoiding failures and guaranteeing the vehicle's safety.
  
• Oil & Gas industries. Refining oil involves high temperatures in boilers and equipment, as well as sudden cooling processes. Thermal insulation increases thermal shock resistance and guarantees the equipment's integrity.
  
• Home Appliances. In a domestic setting, insulation can be found in ovens, which can reach internal temperatures ranging from 356°F (180°C) to 680°F (360°C) while the exterior is kept at a safe temperature. Thermal insulation prevents dangerous thermal shocks and allows safe operation.

Best practices

Planning and preventive maintenance

Proper planning and preventive maintenance routines are integral to avoiding thermal shock downtime. Implement the following best practices consistently: 

• Regular inspection: Periodic equipment and system inspection helps detect wear or damage before the thermal shock occurs.
  
• Scheduled replacements: Plan replacements before any piece of equipment or insulation system reaches the end of its expected lifespan.

Staff training and awareness

Staff training and risk awareness are crucial to thermal shock prevention:

• Staff Training: Ensures staff is prepared and can effectively manage thermal shock.
  
• Awareness: Promotes understanding of the risks of thermal shock and the importance of following best practices.

Conclusion

In summation, thermal shock is a phenomenon that can have severe consequences in various instances. However, with proper understanding and thoughtful design, including the use of effective thermal insulation and the implementation of good operational practice, it can be effectively avoided.

Thermal shock management protects assets and efficiency, improves safety, and reduces operating costs. Having it under control is a worthwhile investment in any environment where changing temperatures may pose a tangible risk.