These days, many heating processes using high pressure steam, but some of them still using thermal heat transfer oil.
Thermal heat transfer oil require periodic sampling and analysis. From the analysis result, the oil sales person or so-called application engineer will be very happy when your oil shows some signs of deteriorating in some specification and will propose you to replace with new thermal oil. How can you judge the caution zone and limit zone for yourself?
Basically, first parameter, Viscosity is +/-5% from original oil is caution zone, +/-10% from original oil is the limit.
Secondly is TAN 1.0mgKOH/g caution and 2.0mgKOH/g is the limit zone.
Insoluble Matter below 0.5% weight caution and 1.0% is the limit zone.
Original sampling interval might be 6 months once, then when it enters caution zone, you must make it a 3 month interval.
To determine if you need to exchange the thermal oil for schedule stoppage, you must refer to your history data trend and estimate when the oil will achieve limit zone. More frequent sampling is necessary to confirm. Ensure your sampling point is appropriate and sampler is using correct and consistent methods.
Thermal cracking will show deteriorate in viscosity and flash point, consider flash point base on your equipment and operation safety design.
Proper handling of thermal heat transfer oil can achieve the lifespan 10 to 20 over years.
Reader Tip provided by Thye Luen Mok, Assistant Engineering Manager, Fatty Chemical Malaysia, Prai Industrial Complex, Malaysia
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