pressurized deaerator safety valve setting
pressurized deaerator safety valve setting
(OP)
Hello friends, I have a pressurized deaerator. Operating pressure 0.2 barg, max allowable operating pressure 2 barg. All instruments and gauges are rated for max 1 barg. Feedwater pumps are also rated up to 120 C (~1 barg).
What should the safety valve be set to? I am planning to set it to pop at 0.5 barg. Is that reasonable?
What should the safety valve be set to? I am planning to set it to pop at 0.5 barg. Is that reasonable?





RE: pressurized deaerator safety valve setting
If the deaerator is built and certified in accordance with the ASME or other pressure vessel standards, the setpoint should be set according to those standards.
However, it is vitally important that the CAPACITY of that safety valve be set in accordance with the worst case possible for the particular plant in which the DA is installed. Typically (but not always) this would include maximum possible steam flow into the DA
Different plant configurations could mean different safety valve configurations....
Multiple safety devices are permitted and the safety device can be located on steam piping
http://www.heatexchange.org/pdf/techsheets/techshe...
"What doyathink" engineering is not acceptable ....
Tell us more about your specific configuration.
MJCronin
Sr. Process Engineer
RE: pressurized deaerator safety valve setting
I would first get a better understanding of what scenario can actually cause you to reach your vessel MAWP. Would recommend digging into additional details on your system to have a better understanding of it and work from there.
Thanks,
Ehzin
RE: pressurized deaerator safety valve setting
ASME specifies no more than 10% over MAWP. They do not specify a lower limit.
The deaerator is 7m above the pumps for maximizing inlet pressure. What is more of an issue is temperature. According to the nameplate 120 C is max, but even at lower temperature I can hear signs of cavitation.
I guess what I am trying to ask is this. The MAWP is much greater than the actual working pressure. It is most certainly an error condition if the actual working pressure even starts to approach the MAWP. The instruments won't survive it, the pumps will cavitate. So shouldn't the safety valve setting be set to prevent this from happening? Why are people only concerned with mawp?
RE: pressurized deaerator safety valve setting
You are conflating two issues. Safety valves on pressure vessels were never intended to protect pumps or facilitate operations. They are meant to protect vessels from catastrophic failure.
Adequate NPSH for feedwater pumps is ensured by proper pump design, pump selection and plant configuration ... not by playing around with DA Safety valve setpoint.
What is your NPSH margin and were these FW pumps sized properly ? Are these pumps being re-used from another facility ?
The ASME pressure vessel code also says that the code Safety Valves shall be set at the vessel MAWP. Nothing says you are forbidden from adding additional relief devices that actuate at a lower pressure.... Do what you want.
https://www.esmagazine.com/articles/95550-safety-v...-
Amazing,...I believe that you questions should have been posted in the "Safety Relief Valve Engineering" forum
Good Luck ....
MJCronin
Sr. Process Engineer
RE: pressurized deaerator safety valve setting
Yup, read that one already.
Thus, the dilemma. Why have 2 when 1 will suffice? In a boiler there are two to increase the discharge capacity progressively. But here, is there such a need? I was hoping for people experienced with deaerator installation/operation to share their experience, but perhaps you're right. Maybe they all hang out in the safety valve forum.
RE: pressurized deaerator safety valve setting
There is a clear discussion of this topic by people who have been selling DAs for decades
https://deaerator.com/deaerator-products/deaerator...
Call up the Kansas City DA people and tell them they don't know what they are doing.
One more question, please tell us just where in the third world you plant is located ...
MJCronin
Sr. Process Engineer
RE: pressurized deaerator safety valve setting
Seems it is not quite as cut and dry as you make sound.
Hence, I came here looking for feedback. Instead all I got was condescending remarks and personal insults from a "senior process engineer". The Kansas City DA people indeed know what they are talking about, while you clearly don't.
Good day.
RE: pressurized deaerator safety valve setting
1)
Thanks,
Ehzin
RE: pressurized deaerator safety valve setting