Regarding the diameter of valves and flow meters
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I would like to ask the students: can the diameter of the valves and flow meters specified in the design be changed to other diameters when making the actual purchase (while keeping the pipe grade and standards unchanged)? Please explain again! Many of the items here have been modified by the participating manufacturers (vendors).
You can calculate the required diameter based on your own manufacturing conditions; the designs provided by design firms may not be entirely accurate, and there might be too much margin included. It’s best to communicate with the design institute before making a decision.
The design institute has already made the decision, but the specifications provided by my side’s participating manufacturers, based on various data related to flow rates, differ from those originally set by the design institute; in other words, they are different from the specifications for the process pipelines. Is that a problem?
It can be changed, depending on the extent of the change. When modifying a flow meter, diameter changes are involved, and for some flow meters, the requirements regarding straight pipe sections must be taken into account.
Thank you to the person above. I’ve never worked in the chemical industry before, and it’s rare to see diameter modification or expansion in other industries; however, many of the projects I’m working on currently involve such modifications by the manufacturers, so I’m a bit worried.
When selecting a product from a design institute, communication with the manufacturer should take place; if the manufacturer changes the diameter, it is necessary to return to the design institute to make the necessary design adjustments.
The key point is that the final design drawings are now ready, and some components have already entered the material procurement stage (such as certain pipes and valves), but the instrumentation has not yet been fully determined. I think the manufacturer will definitely change the diameter later on as well ； I want to connect it to the original process diameter using adapters after changing the diameter of the gauge itself, right?
I think it’s best to take all parameters into consideration during design, and try not to change the diameter or other specifications. Flow meters with different diameters have certain upper and lower limits for flow rate; making too many changes should have some impact on the flow meter
I agree with what was said upstairs as well, but in the technical specifications provided by the manufacturer later on, most of my specified diameters were changed. I wonder if you have encountered situations where the design diameters were altered to a large extent? If that’s the case, what are the issues when using it? (It’s better if it’s already been used.)
Under normal circumstances, it is feasible as long as the measurement range of the flow meter meets the requirements of the process measurement, the flow capacity of the control valve satisfies the requirements regarding its control performance, and the pressure difference before and after the control valve does not exceed the system’s allowable pressure loss. If the pressure drop is too large and the system pressure is insufficient, careful consideration is needed.
You can calculate the c value by yourself and then check the table to see if the diameter is appropriate