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Maintain your carburizing furnace and prevent from leaking!

August 18, 2019
By 猷绥
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Maintain your carburizing furnace and prevent from leaking!

Carburizing furnace might be leaking over time, thus the lubrication part of the driving device may be lack of oil, and the thermocouple in the ignition head may also be blown off. Therefore, we are sharing with you instructions of monthly maintenance of carburizing furnaces, as below.

1. Media pipes

Pipes of compressed air, cooling water, quenching oil and process media on the furnace body will inevitably leak over time. Sometimes leaking positions are difficult to find. After the pipeline leaks, it not only causes waste of the medium, but also may cause serious accidents.

For example, if methanol leaks at the junction of the mixed gas nozzle without being discovered for a long time, methanol will accumulate at the top of the furnace. Once the methanol encounters an open flame or high temperature, they will be quickly ignited, then Burning on the top of the furnace, it is very likely that the top of the furnace and the components on both sides will be burned out.

As part of preventive maintenance, all pipes of compressed air, cooling water, quenching oil and process media should be checked every month, and fix leaking parts with sealing materials.

The pipes can be checked with soap water except ammonia, which dissolves in water. The ammonia gas pipeline should be checked with ammonia detector or pressurization with nitrogen. The liquid pipelines such as cooling water, quenching oil, hydraulic oil, methanol, acetone, etc. should be cleaned before inspection.

After above leak detection, all pipe joints should be tightened to prevent loosening.

2. Drive Motors

Multiple motors are installed on the furnace, including atmosphere circulation fan motor, oil circulation motor, load driving motor, chain driving motor and air blower, wherein the atmosphere circulation fan motor, oil circulation motor and air blower are running 24 hours. As time passes, the bearings may be noisy or vibrating. If so, stop the motor and replace the bearings. otherwise whole motor might be completely damaged.

3. Over pressure flaps

Over pressure flap mainly serves two purposes:

  1. Discharge exhaust gas (carbon monoxide, hydrogen, nitrogen, etc.), ignite and burn off the gas with flame, and finally discharged to atmosphere from exhaust pipe after environmental process.
  2. Release the furnace pressure to a normal state when the instantaneous pressure in the furnace is too large, the entire over pressure flap will be opened at this time.

Due to its working temperature, over pressure flap is prone to deformation over time, and carbon deposit may cumulate as well. Therefore, the Over pressure flap should be removed and cleaned every month. At the same time, check the flatness, replace the flap immediately if it deformed.

There is a flame igniter by the side of the over pressure flap. It ignites exhaust gas. There is a thermocouple with a feedback voltage signal inside the igniter. which sends to flow control valve coil signal that locks flow control valve, thereby retains gas supply to the igniter. However, the thermocouple damages very easily under high temperature. Check the thermocouple at least once a month. replace the thermocouple when it is damaged.

4. Transferring system

Heat treatment furnaces work in high temperature environments. the internal moving parts are prone to failure over long time. In order to detect potential failures, drain furnace gas every month, set the equipment to "adjustment mode". Manually operate all furnace doors, lifting platforms, check if these components operate smoothly and noise-free; If abnormalities are found during manual operation, the equipment needs to be cooled down for necessary maintenance.

5. Inside the chain tunnel

After using the furnace for a period of time, dirt and quenching oil may be deposited inside the chain tunnel. Therefore, cleaning should be done every month: open the cover plate of chain tunnel. clean up dirt or quenching oil deposited, then re-cover the tunnel and ensure the tightness. In case the furnace is gassed, detect leakage with flame torch. If it leaks, gas can be ignited through leaking part. Open the outer furnace door and extinguish the flame, and then the seal of the leaking part of the chain tunnel cover will be trimmed or replaced to ensure that this part does not leak.

6. Oil circulation, furnace chain, feeding device

According to the lubrication requirements, following parts should be lubricated every month:

  1. Self-aligning bearing at the upper end of the oil circulation motor; fill with ordinary grease. Refill grease until grease is seen at the bearing end cap.
  2. Bearings at both ends of the furnace chain drive shaft; fill with ordinary grease. Refill grease until grease is seen at the bearing end cap.
  3. Feeding device clutch cylinder drive shaft and bushing and limit gear driven gear bushing; fill with ordinary grease. Refill grease until grease is seen at the bearing end cap.

7. Electrical cabinet

Open the electric cabinet and check the inside and outside if wiring is clean and clean. Since the heating circuit current is relatively large, if the line is in poor contact, heat will be generated and the electrical components will be burnt out. Therefore, tighten every of each cable on the heating circuit.

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