Yes maybe I'll have to read more about the 3% rule. If it is true that the omly factors that affect capacity are inlet and outlet pressure, and the inlet piping pressure loss only affects overpressure, then it is likely that the reduced capacity that my program was seeing may be from the...
Yes trying to avoid undercapacity caused by excessive inlet piping.
Yes that would be ideal, but it should be noted that laying out long sense lines could be dangerous and increases the risk of third party damage. if someone breaks your sense line that is a big problem.
Ok let me clarify. The application is a model of regulator (the same that might be used to step down the pressure from 100 to 40 psi) but configured with a pilot to operate as a relief valve. Not a model of backpressure regulators.
That's interesting. My role is to scrutinize existing designs. These backpressure regulators were stamped by a PE and approved by regulators. I guess its possible they didn't realise?
I kind of thought that the pressure buildup would be less than 5% of set point since it is pilot operated. But now that I think of it pilot operated regulators can't hold their setpoint at high flows. So 5% could be possible. Do you really expect 5%? Because that definitely hurts, that's...
"What PSV protects? What is piping design code and pressure rating? What is relieving temperature?"
It protects a natural gas distribution system. I think we have multiple at various operating pressures. 40 or 60 psi maop. Allowable ovrrpressure by federal code is 6 psi over maop for piping...
For this theoretical discussion lets say 5 psi more more than 3% of set pressure.
Typical relief valve designs for my application are pilot operated backpressure regulators.
The capacity of the relief valve is affected by the inlet pressure at the relief valve, the relief valve set point, and...
So we have engineering software that is capable of calculating the effect that the piping has on a relief valve. But how is it doing it? What is engineering theory that would provide an analytical solution to how much a relief valve is affected by pressure loss?
The typical relief valve...
20 psi could make a huge difference. Imagine running your 200 psi system at 180, or your 100 psi system at 80. Imagine if the transmission pressure drops by 600 psi. 20 psi could save you.
Ya I'll have to get to know my regulators better.
It might be difficult or impossible to get the permits you need in time if the pipe goes under a highway, railroad, over a bridge especially if it is condemned, or if you need to obtain easements for an alternate route.
Ya that could be helpful but certainly regulators are not infallible. They still make mistakes too. And unless you already know the regulator that would be involved in your design then they could just come in with a bunch of bad ideas and then you have to do it because they are the regulator...
Yes the Merrimack Valley incident was due to improperly placed sense lines not a bypass. But there are also incidents on record where people have died in the cold.
"It’s been a year since millions of Texans woke up to find their power cut during the freezing cold. What followed were days...
At 3 am when shit hits the fan good luck getting ahold of governing agencies for their stake in the decision making. I don't know what makes them competent in this situation because they don't know your system.
There is no need to provide a bypass for maintenance because there should already...
Thought this thread discussing gate station bypasses was interesting.
thread378-465800
So let me ask:
Should natural gas gate stations have a manual or semi-automatic bypass? What sorts of designs would constitute a sound bypass run? A bypass with OPP, no OPP? A manual or automatic...
