Maintenance

Best practises for Steel Yankee Dryer

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Maintenance managers and supervisors in tissue mills are required to work to budget and cut the costs of maintenance wherever possible. An efficient management of TT SYD (Steel Yankee Dryer) helps reduce maintenance costs and avoiding the risk of emergency stops.

Toscotec published to do to reduce the maintenance cost of your TT SYD:

1.   Within 2 years after start-up and every 5 years after the first inspection, you should perform structural checks and NDE of the structural welds and connecting bolts of your Yankee, according the following Non Destructive Examination (NDE) methods: Magnetic Particle Inspection (MPI), single beam Ultrasonic Testing (UT) and automated ultrasonic testing (Phased Array – PA and Time Of Flight Diffraction – TOFD).

2.   Once a year, plan an internal inspection of your TT SYD and its condensate removal system. Make sure you thoroughly clean the soda straws – one by one, from the bottom of the grooves – and their blocking clips.

3.   The chemical parameters of the boiler’s water circuit and of the Yankee’s condensate must remain within the recommended ranges.

4.   Perform a visual inspection of the metallized surface on each shut-down of the paper machine.

5.   Once a year, measure the roughness of the metallized coated surface.

6.   The insulating sleeves protect the bearings, especially during warm-up of the Yankee. Once a year, check if the insulation sleeves are working properly by using a contact thermometer to measure the temperature of the Yankee journals during production. Once every 5 years, perform a pressure test or dismantle the insulating sleeve pipes (depending on your type of sleeve), in order to verify the conditions and good functioning of the sleeves. Repair or replace any damaged part. It is good practice to replace the gaskets and insulation packing/wrap after 5 years of operation.

7.   At least once a year, during ordinary maintenance, check the tightening of the SYD deckle insulation screws. At least once a year, you should also thoroughly clean the deckle insulating panels. If the TT SYD is at room temperature, you may use high-pressure water to do so.

8.   The doctor blades should be of the right length and mounted cantered in the middle, to make sure that they cover the Yankee’s surface completely during the oscillation of their support. Usually, the rule is LBLADE = LYD – LOSCILLATION.If you use oscillating doctor blade holders, make sure that their movement is smooth and steady.

9.   Check the wear level of the sealing graphite according to the indications of the supplier. If it exceeds the maximum allowable wear, replace the sealing graphite during machine stop and with the steam rotary joints at room temperature.

10. Once a year, measure the TIR (Total Indicated Runout) of your TT SYD. Measure the TIR at grinding pressure and with the paper sheet off. You may also do this measurement in cold conditions, to get a rough indication of roundness status of your SYD.

11. In case of long-term shut-down, remove all the condensate inside the Yankee dryer, clean the heads/deckle insulation panels and remember to rotate the Yankee by 90° once every two days.

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