High temperature for hydraulic oil of bypass system at the line coming from the HP bypass valve, LPA bypass valve & LPB bypass valve. There is a problem for bypass system where the temperature of the hydraulic oil increased from 54 C TO 67 C. When the oil coming from bypass valves, we try to increase the size of oil cooler but the temprature didn't change. please adviced me about solving this problem.

 

<b>WHEN</b> did this problem begin? That should be the first question for troubleshooting any problem, especially when the system was running without problems and then there is a problem. If it started after a maintenance outage when piping was disassembled and reassembled, then you need to look at how the piping was reassembled, including any insulation, etc.

There is absolutely <b>NO PRACTICAL WAY</b> we can help you with this problem without being able to see the physical installation and the P&IDs for this installation.

It's also very difficult to understand what you're saying. If you're saying that the oil returning from the bypass valves has increased in temperature, that would be somewhat understandable, right? The oil is cooled before it's sent to servos/actuators, whether that's before it enters the tank or after the pump(s).

It's not in dispute that some temperature rise is normal; but we don't have any idea if this is a sudden or abnormal temperature rise. Only your logs can tell you that.

As an analogy, oil sent to bearings is cooled before it's sent to the bearings, and is always at a higher temperature when it returns from the bearings.

I have seen poorly routed oil- and steam piping, and modified oil- and steam piping, that were not properly insulated.

But, other than that, you would seem to be on your own with this problem.

 

> <b>WHEN</b> did this problem begin? That should be the first question for troubleshooting any problem, especially when the system was running without problems and then there is a problem. <

The history of the problem as follows:

1-By pass system started since 1997 & there are problems for hydraulic oil tank temperature increased & the oil pumps damaged many times.

2-hydraulic oil tank temperature increased especially at summer where it increased to 45c & at winter to 30 c.

3- due to hydraulic oil tank temperature increased the acidity of oil is increased than the allowable value many times (double or more)& According to troubleshooting manual oil acidity higher causes pumps problems .

4-the oil pumps ( Swash Plate Pumps- Manufacturer: Rexorth- Type: A10VSO18DR/30RVKC62N00) & it have a cooling line to Saddle Bearing & the cooling oil restore to the oil tank.

5-the problems start by hydraulic oil tank temperature increased & after that the pump pressure decreased causing a sound effect until the pressure going to zero pressure ( The normal pressure of the pumps 3000 psi) When the pumps dismantling we find wear at the saddle bearing & pistons.

6-The hydraulic oil tank has one air cooler & during solving the higher temperature we install another air cooler in series but the problem still exist then we dismantle the new air cooler.

Please be advised to solve the problem
Thanks,
GSA

 

What if the problem is in reverse. The damaged hydraulic pump is causing higher hydraulic fluid temperatures. Say, for example, something changed within the process or the machine, which is causing higher wear and tear of the pump. Was the hydraulic fluid type changed? Or were any repairs carried out?

Regards,
Tomy Zacharia

 

My dear friend,

I do not know much about mechanical equipment. However, I would like to add one more dimension to the discussion.

Can't CAVITATION be a culprit in this case ? As noise is heard and Lube oil temperature is remaining very high, Pump may be cavitating. So, Due to cavitation, there may be less oil flow which in turn will result in high lube oil temperature, noise related probelm and wear & tear of pump internals.

Best regards
Ankur

 

Can you send me a copy of the hydraulic circuit?

Your system is generating heat somewhere.

Has the fluid been checked for cleanliness?

Pumps are good to 90C with right fluid.