Choosing conveyor chains that operate at high temperatures is a critical decision for industrial maintenance managers. The wrong material choice can lead to a shorter-than-expected lifespan, production downtime, and additional costs. Particularly in metal processing plants, steel industries, and copper smelters, where operating temperatures can reach up to 400 °C, the material selection and structural properties of the conveyor chain are crucial for system reliability.
Choosing the right high-temperature conveyor chain requires a deep understanding of material properties, operating conditions, and the function of the entire conveyor system. Forged conveyor chains provide a reliable solution for these more demanding applications, when materials and dimensions are carefully selected.
What makes a conveyor chain suitable for high temperatures?
Resistance to high temperatures in conveyor chains is based on the retention of the material's mechanical properties in heat, structural protection, and controlled temperature management. The chain must maintain sufficient tensile strength and surface hardness even at elevated temperatures.
As the temperature rises, the tensile strength and surface hardness of ordinary steels weaken significantly. This makes the chain more susceptible to wear and can lead to unexpected damage. For example, a manganese steel chain loses its properties at temperatures as low as 200°C, whereas boron-alloyed steels retain their mechanical properties better up to 400°C.
Structural protection is as important as material selection. The chain guard must prevent direct contact with the chain from both radiant heat and hot material pieces. Thermal shock, which occurs when hot lumps hit a cold chain, can cause permanent deformations and weaken the chain's alignment.
Which materials withstand heat best in conveyor chains?
Boronised steels, particularly 27MnCrB5 steel, have proven to be excellent materials for hot and abrasive conditions. Boron steel retains its toughness and can withstand continuous thermal load exceptionally well up to 400°C, whereas standard manganese steel (20MnCr5) is only suitable for lighter applications.
Booriteräksen erikoisominaisuudet tulevat esiin lämpökäsittelyssä. Toisin kuin mangaaniteräs, joka karkaistuu vain pinnaltaan, booriteräs läpikarkaistuu lähes kokonaan. Tämä tekee ketjulenkeistä sitkeämpiä ja kulutusta paremmin kestäviä. Pintakovuus on huoneenlämpötilassa noin 30 %korkeampi kuin mangaaniteräksellä, ja korkeassa lämpötilassa ero kasvaa jopa 70 % :iin.
Comparison of materials by operating temperatures:
- Manganese steel (20MnCr5) Suitable for light-duty applications; maximum operating temperature approximately 200 °C
- Boron steel (27MnCrB5) For demanding conditions; continuous operating temperature 300–400 °C
- Special alloy steel: For extreme conditions, application-specifically
When selecting materials, it must be taken into account that a boron steel chain also wears during use. In addition to the material, the transport speed significantly affects wear, which increases wear exponentially as speed increases.
How to choose the right conveyor chain for your application
The selection of the appropriate conveyor chain is based on a comprehensive assessment of the operating temperature, load, properties of the material being conveyed, and the operating environment. Critical factors include the continuous operating temperature, shock loads, and the corrosion risk of the process environment.
Determining the temperature range is the first step. If the continuous operating temperature exceeds 250°C, a standard manganese chain is not suitable for the application. The temperature range of 250–400°C requires a boron steel chain and careful temperature management. Too low an internal temperature can lead to the formation of sulfuric acid as a result of exceeding the acid dew point, which accelerates corrosion.
Load assessment includes both continuous tensile loading and impact loads. In smelter waste heat recovery boilers, the chain operates under continuous tensile load, but simultaneously, impacts caused by accumulations of conveyed material can be significant. In this case, the 216W-rear-link chain offers 44 % higher breaking strength compared to the traditional 142V chain.
Practical selection criteria by application:
- Applications at 200 °C: 142V manganese chain may suffice in light conditions
- 250–400 °C continuous temperature: The 216W tungsten carbide chain is recommended
- Intermittent loads A more robust chain size and a protected structure are essential
- Corrosion environment Temperature control and material selection are critical
What are the maintenance requirements for high-temperature conveyor chains?
Conveyor chains for high temperatures require regular temperature monitoring, insulation condition checks, and inspection of chain protection. The focus of maintenance is to keep the temperature range within an optimal window of 250–400°C, balancing the mechanical properties of the chain with the risk of internal corrosion.
Temperature control is the most critical maintenance task. If the internal temperature of the conveyor drops below the acid dew point, sulphuric acid will form from the process gases, significantly accelerating corrosion. On the other hand, too high a temperature weakens the chain's properties and can cause thermal shock. Regular inspection and maintenance of the insulation will ensure the temperature remains within the target range.
The condition of the chain guard directly affects the chain's service life. The guard must prevent direct contact with both radiant heat and hot material pieces from reaching the chain. Damaged guards expose the chain to thermal shocks and mechanical impacts, which can cause permanent deformation.
Practical maintenance measures include:
- Temperature monitoring and insulation condition monitoring
- Regular inspection and repair of the chain guard
- Simultaneous replacement of chainrings with the chain
- Optimising transport speed to minimise wear
- Assessment and adjustment of load distribution
An unforeseen need to change a chain is often a sign that one of these factors is not right. Expert chain selection and the right maintenance practices can significantly extend replacement intervals and improve production reliability. A comprehensive approach, viewing the chain as part of the entire conveyor system, is key to long-term operational reliability in demanding conditions. If you want to ensure that your next chain selection performs as expected, Get in touch, so we'll go through your application's requirements in detail.
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