HEATER MAINTENANCE TIPS:

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WATTS' Tips for Extracting Maximum Life from a Heater

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Heaters, being Plug & Play accessories of the Furnace / Heating Equipment, are often forgotten after installation and little or no maintenance activity is carried out in a lot of companies which results in early failures and other much bigger headaches like sudden shutdowns and production losses.

If these basic steps are kept in mind during and after installation of the Heaters, a much more efficient system, reduced maintenance costs and maximum life can be extracted from the heaters and heating systems.

 

HEATER CLEANLINESS:

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After observing failed Heaters, one of the most prominent causes of failures concluded was Cleanliness of the Heaters. Heaters in specific atmospheres gather a lot of oxidized material on them which if not cleaned during the Preventive Maintenance process, lead to failures. For Naked filament radiation heaters, a protective coat of Chromium Oxide is formed which prevents the Base metal (Nickel) from oxidation. However, if there is a deposition of some metallic oxides from the charge, or deposition due to High RPM re-circulating fans is caused, it is necessary to clean them. For Immersion type of heating elements, the deposition of oxides is very high which reduces the efficiency of the heater. So regular cleaning is a must.

 

GUARDING THE TERMINALS FROM EXCESS ELECTRICAL & THERMAL SHOCKS

 

Termination should be done a little away from the Heating Section .WATTS’ designers ensure the same while designing the customized Heaters for their clients. 

If the terminals are threaded, then it is mandatory to tighten the nuts and lock- nuts (if provided) to prevent sparking and causing termination damage. A detailed check of the same needs to be carried out every 15 - 20 days for avoiding the loosening of the Nuts. In some cases, WATTS provides Isolators for the terminals, which provide them with extra safety. These isolators can easily be replaced with new ones and it does not become a mandate to replace the heaters wherein only the terminals have been damaged. WATTS’ designers custom design these Isolators considering their current carrying capacities. 

Usage of Top quality fiberglass cables is a must to avoid early damage to terminals. The current carrying capacity of the cables has to calculate adding extra safety factors. 

Terminal covers are a must for all naked terminals from safety point of view as well as to avoid any dust, depositions etc. mounting on the terminals.

 

CHECK THE GROUNDING OF THE EQUIPMENT

 

For Safety purposes, it is important, as well as a general practice, to ground the equipment to avoid accidents and Equipment failures.

 

CHECK THE DESIGN VOLTAGE & THE APPLIED HEATER VOLTAGE

 

WATTS tags each and every element to make it easier for the Installation Personnel to understand the design Voltage of the Heater. It is essential to ensure the design voltage matches the applied voltage (in + 5% tolerance). Because if it doesn’t, the KW Rating of the heater varies directly to the Voltage squared. So to avoid early failures, it is essential to not vary the design voltage of the Heater.

 

 

AVOID THERMAL SHOCKS TO THE HEATING ELEMENTS

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A regular failure of Heating Elements usually happens due to the continuous Thermal shocks incurred by the Heating Element. This causes constant expansion and contraction of the Element and it eventually loses form. In naked filament radiation Heaters, it causes severe stresses on the strip / wire which fuses with the adjacent turns and shortens the current flow, and eventually sparking or damaging the portion completely.

 A control panel with PID, SSR or Thyristor control (for Phase angle firing) is used to reduce thermal shocks on the Element and also get a uniform temperature gradient.  

 

REGULAR CHECKS OF RADIANT TUBES

 

A Radiant tube increases the life of a Heater by protecting the fast oxidation of the element in corrosive atmospheres. But if the tube itself is not serviced properly during the Preventive maintenance, then there is a chance of the inner layer of the tube chipping off and falling on the Element itself and fusing / shorting it. There are also chances of the tube deforming / sagging and eventually touching the element, thus fusing it.

To avoid this, remove the Radiant tube and clean it with a metal brush from the inside. Also, remove any oxidized material inside the tube. Once cleaned, install it in the furnace. It is also recommended to invert any tubes (installed horizontally) which were previously sagging, by 180 degrees. Sagging or no sagging, WATTS recommends all horizontally installed tubes to be turned 180 degrees every 3 months so that they nullify any deformation that has occurred during the thermal expansion and contraction.