Questions regarding the installation of pressure transmitters and differential pressure transmitters?
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The differential pressure transmitter is installed on the storage tank, and the medium being measured is acetic acid. May I ask if a flange connection is absolutely necessary? How is the flange size determined? Can it be connected with threads? In what situations is it appropriate to use threaded connections for pressure transmitters, and when is it better to use flanged connections?
Generally, flanges are used for high pressures, while threads are used for low pressures
For pressure transmitters used in equipment such as storage tanks, they are generally installed using flanges. Flanges are divided into threaded flanges and welded flanges. For low-pressure, small-diameter threaded flanges are used, while welded flanges are employed for both high-pressure and low-pressure large-diameter flanges. Flange connections are easy to use and can withstand high pressures. Flange connections are widely used in industrial pipelines. Flange connection is a detachable connection. Common overall flanges include flat welding flanges and butt welding flanges. Flat welding flanges have poor rigidity and are suitable for applications with a pressure of p≤4MPa ； Butt weld flanges, also known as high-neck flanges, have high rigidity and are suitable for applications with high pressure and temperature. There are three types of flange sealing surfaces: the flat-type sealing surface, which is suitable for applications with low pressure and non-toxic media ； Roughened sealing surface, suitable for applications with slightly higher pressure ； Tenon-and-socket sealing surface, suitable for flammable, explosive, toxic media and high-pressure applications.
Flanges are used for high pressure, while threads are used for low pressure; the interface size is selected according to the pressure transmitter specifications.
Personally, I think flanges provide good sealing, while threaded connections are prone to damage during disassembly! !
On storage tanks, how is threading used for connections? I’m just starting out with design and don’t quite understand this. Could someone please explain it? I’d be extremely grateful. The pressure is relatively low, at 0.002 MPa; the medium is acetic acid, and a differential pressure transmitter is being used. Should a threaded connection be used? So how exactly is it connected to the storage tank? According to the manufacturing process, flanges can only be used
What was said upstairs is that perhaps a threaded hole can be drilled in the flanged blind plate, so that a threaded connection can be used on the instrument side
Excuse me, up there – should I still use threading for the connections in my data table? Based on my process conditions, is threading sufficient for this situation?
If he uses flanges on the process side, he’s asking me now what size the flange openings should be – is 80 usually the standard size? How was this caliber determined?
Differential pressure is generally connected using flanges. If threads must be used, specify “flange with threads” in the connection method“ ； Generally, DN25 is sufficient for flange connections. However, I still strongly recommend using flange connections.
It is cheaper to install a pressure-taking stop valve along with a pressure transmitter than to use a flanged pressure (differential pressure) transmitter.
Firstly, 0.002 MPa measures the vaporization of acetic acid in the gas phase; or is there a slightly positive pressure of nitrogen air in your storage tank? It is estimated that the latter possibility is higher. If a differential pressure transmitter is used and the process pipe connections are flanged, then a blind flange with a center hole of Φ22 corresponding to the size of the process opening is required, along with a short pipe and a DN15 gate valve; these are materials to be provided by the process team ； Next are your reducer Φ22/S.WΦ18 pressure guide tube, stop valve, and transmitter. Given the volatility and corrosiveness of acetic acid, the diaphragm material should be at least 316 grade. The same principle applies if a pressure transmitter is used; it’s just that there is no issue of a negative pressure chamber being exposed to the atmosphere, and the installation process remains the same. If pure volatile acetic acid is being measured, it is recommended to use flange connections, as the corrosiveness and the pungent smell of acetic acid are quite strong. Flange connections provide good sealing. Someone has already given you suggestions in another post; to use a pressure transmitter, you can use the 3051CG model along with a diaphragm-sealed flange of type 1199. It’s sufficient to have a ball valve with a flange of the appropriate size for the process requirements ； The same applies if differential pressure is used; it’s just that the positive-pressure side is a capillary, while the negative-pressure side is connected to the atmosphere. My idea is this. This post was last edited by hwindforce on 2009-3-3 11:31]
The use of flange connections is mainly due to the corrosive nature of acetic acid, which requires isolated measurement. If normal connections are used, there will be too many joints, thereby increasing the risk of leaks. In general, for substances that are toxic or corrosive and require isolated measurement, double-flange transmitters should be used! This is just my personal opinion; it’s for reference only!
Pressure taps on general equipment are connected using flanges, while those on pipes are connected using threads.
Differential pressure transmitters can usually be connected by flange, with DN50 and DN80 as the available diameters
I disagree with the statement on the 2nd floor that flanges are preferred for high-pressure applications; generally, welding is the better choice for high pressure, while threads are usually used for medium pressure.
Flanges aren’t necessarily the best option for high pressures; when the pressure is really high, threaded connections are preferred. Based on my personal experience, for ordinary pressure transmitters, flange connections are generally used in areas with a larger surface area, while threaded connections are more common in areas with a smaller surface area such as pipes. The same principle applies to differential pressure transmitters – threaded connections are used for the pressure tapping tubes
Sure enough, it’s a professional – they’ve studied this; I really hadn’t considered such a professional aspect before.
For media that are highly corrosive and tend to crystallize, flange connections are preferred