Valve and Flow Meter Size with HDPE Pipe

[Thcheme]

Hello all,

I would like some advise on selecting valve and flowmeter sizes when it comes to HDPE piping.

For example, the system utilizes HDPE DN315 PN16 with ID of 256.1 mm. Will the gate valve or electromagnetic flowmeter size be DN300? As per my understanding, this would match the flange drillings of the pipe with the valve as per EN1092, however the internal bores will be mismatched.

Or would the valve size be DN250 which should more or less match the internal bores of the pipe and valve, and probably require flange adaptors due to the mismatch in the flange drillings.

All our HDPE pipes are PN16, with sizes of 110, 200, 250, and 315.

Apologies if this is a silly question but this is not my area of expertise.

Thanks

 

[1503-44]

A full size valve is one that most closely matches the pipe size, however internal diameter, or bore, of a valve is not really a consideration unless pigging is planned, or if it affects the pressure drop and flow you wish to achieve. Many valves have reduced bores. You must specify what ID you want for your valves, if they do not match what a manufacturer typically supplies. In fact it is always advisable to specify your desired valve size, connections size and type and include the ID. This should be done under all circumstances, if for no other reason, to avoid confusion. Its entirely up to you what valve size to use. They are usually the same "nominal" size as the pipe, but can be smaller, or occasionally even larger. It's up to you.

Flow meters and control valves often do not have to be the same size as the pipe, so the question doesn't have much meaning as the internal dimensions must be sized to provide the ranges of pressure drops and and flows you must achieve in the case of control valves and range of flow rates you wish to measure in the metering case. Otherwise, common valve internals are determined by the manufacturer and their usually published Cv or Kv values, which in effect preset those internal dimensions.

If you specify what you want, that's the end of the story.

--Einstein gave the same test to students every year. When asked why he would do something like that, "Because the answers had changed."

 

[wangrich]

The nominal diameter of the gate valve or electromagnetic flowmeter should be consistent with the nominal diameter of the pipeline. Better ask the pipe manufacturer. They're more professional. Our company also produce hdpe pipes, but I am not a technical person. If the problem is not solved, you can reply to me and I will ask our technicians to take a look.

 

[Thcheme]

Thank you for the replies.

This is much easier to do when dealing with steel pipes, but i cant seem to wrap my head around HDPE.

1503-44, there are no process requirements when it comes to the valves. These are only for isolation purposes either manual or pneumatically actuated. No pigging requirments.

I understand your point regarding the flowmeters. I will have to check with the supplier regarding the flows and recommended size.

Wangrich, if it isnt any trouble it would be helpful to get some tips from your team regarding the valves.

Thanks

 

[1503-44]

If they are just plain on/off service valves, it will generally be convenient, no head loss and cost effective (not messing around with unusual connections and adding potential leak points) to simply specify the valve with equal nominal pipe size and with "Full Port", Minimum Bore= XX mm

There are often min and max flow rates for a given meter size in which readings are guaranteed to be within a certain percentage of accuracy, 0.5%, or 1% being common. That may restrict the connection pipe's diameter.

--Einstein gave the same test to students every year. When asked why he would do something like that, "Because the answers had changed."

 

[danw2]

Magnetic flow meters are inherently velocity meters. It is very common to size a magmeter a pipe size smaller than the line size for two reasons - the velocity increases in the smaller meter tube so the accuracy spec looks better and the smaller the tube, the lower the purchase price.

Any legitimate flow meter vendor will size according to your min/max flow rate for whatever pipe size.

 

[LittleInch]

The biggest issue is the mismatch between PE pipe sizing (Actual OD at all diameters), versus nominal OD below DN300.

PE100 and some vendors can supply flanges which match just about the same pipe OD, but you really need to check the catalogues for what pipe size equates to what IPS. In many cases its a metal pipe size one down from the PE pipe size IIRC.



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