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What is the optimum time for switchover between standby rotating equipment?
 
Answers
13/04/2016 A: Shridhar Shenoy, OMPL, shridharbshenoy@gmail.com
Changeover frequency is decided as per condition monitoring schedule. Typically normal process and utility pumps will be changed over once in not more than 15 days. Major or critical equipments are changed over once in a month and monitoring is done online. Few pumps that have one running on steam turbine and other standby on electric motor are mostly changed over during PM requirements ( not less than 2 months)
02/12/2011 A: Bruce Carr, Suncor Inc, bcarr@suncor.com
If you are talking about pumps, we just went through this discussion. We live in a region (Canada)where temperature range from -30C in winter to +30 in Summer. We used to swing every month... in winter we were experiencing a terrible amount of seal failures.... I spent a year monitoring the pump swings... the problem I found was the operators were not properly trained, in fact received no formal training on pump seals and as a result were not starting the spare correctly... it was more by luck and the fact summers are more forgiving than winters that we didn't have more problems... I also researched this question and the definitive answer is the fewer pump swings the better... we also found the pumps were being swung for other reasons separate from the schedule. Our vibration monitoring program also required swinging, our PM program required swinging.... We now have all these programs scheduled to coincide with each other reducing the amount of swings.. I wrote a book for our operators explaining the different seal plans, there was nothing out there written with operators in mind, the quarter section drafting drawings supplied by the seal manufacturers are useless to an operator... I also spent time with each operator ensuring they understood how properly to swing a pump and how important it is to understand the different seal arrangements and their requirements. Our MTBF went from 40 months to over 70 months... Sorry to be long winded.. to answer your question.... swinging pumps so they each get equal running time increases the possibility of double failure. The best practice is to have a designated main pump and designated spare and to run them on a 90%- 10% split.....
11/08/2010 A: Balasubramanian Iyer, Nexen CNOOC Limited, balasubramanian.n@aol.in
We follow rotation of standby rotary equipment once in 15 days and it may also be done once in a month. Giving too long gap will affect the life of the Rotary Equipment. If long time is given then it is better to Rotate the shaft with hand and check for its free movement and then change over to the stand by.
16/01/2010 A: G KAMALAKANNAN, Foster Wheeler India Ltd, siddhukamal@yahoo.co.in
It depends on the capacity and accessories of the pump/compressor. If lube oil systems are there, first the lube oil system is to be taken on line. If dry gas seal is there for compressor, it has to be taken on line. Then the standby pump/compressor shall be taken on line without disturbing the process flows.
The range of time is between 5 min to 30 min.