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In our VDU furnace there are 4 cells & 1 coil/cell. In last few days suddenly few coils in cell 1,2 & 4 from the bottom started lifting up from the support inside radiation zone. Even few coils are floating continuously. While RCO entering the furnace pass4 comes first then 3,2 &1. Coils are horizontal. What could be the reason?
 
Answers
30/07/2015 A: Eric Vetters, ProCorr Consulting Services, ewvetters@yahoo.com
Was there any sort of upset on the unit? Have the skin temperatures on the tubes suddenly increased? It sounds to me like there was some sort of episode that caused a lot of fouling of some tubes. The increased skin temperatures caused thermal expansion of the tubes, which has forced some of the tubes off of their hangars. This phenomenon is not that unusual and does not necessarily have any impact on the ability of the tubes to function from a mechanical integrity standpoint.