Hydraulic Supply Piping to Actuator

[Aptx4869]

Hi

We have a hydraulic system controlling a stop valve for the steam turbine. As per OEM, it is required to do test for this valve on daily basis

The supply oil to actuator is via a piping (hydraulic SAE flange) and the piping has a support. But I can see the piping sometimes vibrate during valve actuation. This is common on all steam turbines we have. Even the piping support after years will get its bolts loose from vibration.

Recently, one of the piping developed a crack at the weld joint which could be due fatigue.

Is it possible to switch into a hydraulic hose (instead of piping/tube) like attached if the hose can withstand the pressure ? Any standards/codes to know if this is acceptable or not ? or we have to review the locations of supports ? what standards to use ?



Thanks

 

[TugboatEng]

What temperatures do you expect to see at the hose?

 

[Aptx4869]

As per P&ID,

Normal Temp is 115 F and Maximum Temp is 150 F. This is for the hydraulic oil

For surroundings, I have to check. The actuator is on an open area but maybe subjected to nearby heat. I will check the tube surface temp by a temp gun

Hoses are ok up to what Temp ?

 

[TugboatEng]

Standard hoses ratings are 212°F, 257°F, and 302°F.

The outer surface can be protected with insulated sleeving.

What is the system pressure?

 

[Aptx4869]

Normal Pressure is 2400 Psig
Maximum Pressure is 3000 Psig

 

[BrianPetersen]

Hoses are very commonly used in that application. Industrial supply shops with hydraulic specialists can help you with selecting the correct fittings and hose, and assembling the end fittings to the hose (which requires specialist tools). Call a local one and get them to send someone over to have a look.

 

[TugboatEng]

It sounds like this application has no special requirements. ISO 18572 should fit the bill. If you're in the USA there are parallel SAE standards what could also work.

 

[Aptx4869]

Thank you all.

I will invite Parker Hannifin to a site visit for evaluation.

 

[stgrme]

A hydraulic oil system for a steam turbine is not a typical industrial application. Steam turbine manufacturers recommend piping (not hoses) up to the valve actuator due to the fire hazard if hydraulic oil sprays onto a hot surface.

Lube oil, used as a hydraulic oil, as well as most synthetic hydraulic oils will burn when sprayed onto a hot surface. Some fire resistant hydraulic oils have been shown to smoulder and/or burn when sprayed onto turbine insulation materials.

I would recommend contacting the turbine manufacturer for their advice on using hoses versus piping for hydraulic oil supply to the valve actuators. The manufacturer may also have recommendations on support of the piping to minimize vibration of the piping.

Best of luck!

 

[TugboatEng]

Keep in mind that OP has already experienced failures of the pipe. Those concerns are certainly valid but also easily minimized. Minimize the risk of fire with spray shields/jacketing. Minimize the risk of leakage through proper hose selection and consider scheduled replacement.

 

[IceStationZebra]

Could also consider a short section of metal braided hose on either end of the pipe to isolate the vibration. ISZ