The valves reserved for utility services are too small; how to solve this?
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For the new project, the pipeline valves reserved for the circulating water main in the first phase of the utility systems are DN250. However, calculations show that 500 tons per hour of circulating water is required. Given that DN300 pipes would be more suitable, it would be necessary to modify the pipe connections. Now, we are wondering whether it is possible to install a DN300*250 reducer at the valve without interrupting the circulation of water. Would this turn the valve into a flow-limiting orifice plate, and could the required flow rate still be achieved? I’d like to ask the experts!
Just drill another hole nearby – drill it while there’s pressure, no need to shut off the water to release pressure
It’s easy to talk about, but welding it is quite troublesome!
A reduction in diameter of 300/250 is implemented downstream of the valve; for the pipeline after this reduction, a DN300 pipeline will suffice. It is possible to try reducing the circulating water pressure in the system downstream of the valve slightly
This post was last edited by Qingchengjun on 2021-1-11 at 10:34. It seems that the difference between 250 and 300 isn’t significant; the valves don’t need to be fully open during normal operation. The valves should be sufficient, with only a slightly higher local pressure drop. If the pipes are changed to 300, the overall pressure drop across the system will be sufficient for normal operation. In factories, for pipes with a diameter of over 100, the valves are one size smaller than the pipes. The diameter of the pipe narrows at the valve location, and then widens again after the valve, so that the flow velocity is higher when the fluid passes through the valve. A smaller flow path facilitates precise control of the flow rate; if the valve is too large, even slight movements can cause significant changes in the flow rate, making it difficult to control it. 300 tubes with 250 valves is reasonable.
The flow velocity in the DN300 pipe is 1.96 m/s, which is close to the upper limit of the empirical flow velocity; if investment costs can be disregarded, a DN350*250 reduction fitting can be added downstream of the valve.
If it’s a ball valve, there’s no need to replace it; it’s good enough! The gate valve should be sufficient as well; the flow velocity at the valve can be set at a higher value!
The flow rate is indeed a bit higher; there’s hardly any space left in the main ducts. Usually, I prefer a flow rate of 1 to 1.5 meters!
There are specialized companies that handle pressure-driven hole opening; water pipes shouldn’t be complicated