reducer before tee

[Prototyp]

A DN400 pipe splits into two DN300 pipes. Flow direction is from DN400 end towards the two DN300 ends (figure). Unfortunately due to space limitations the reduction was mounted before the tee at the DN400 end instead of after the tee. Maximum flow will be 972 m³/h at 8 bar of oil (viscosity ~20 cSt).

Could this turn out a problem during operation?

 

[MortenA]

If its clean sirvice and dP is not critical then i would say no

 

[LittleInch]

Not ideal and at a velocity of about 3.7m/sec in the 300 section a little faster than ideal, but as said with a clean fluid you should be ok.

It will though always look a little bit "odd" so if you can change it then all the better.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[zdas04]

Assuming that the flow is in the region where the Bernoulli Equation is valid (and most pipeline flows are), then you get a slight pressure decrease in the reducer as velocity increases, then a measurable (but still small) pressure increase from the reduced velocity in the two pipes. I've measured the pressure in a couple of lines with the configuration you've shown and with very sensitive instruments I can't ever see a difference between your configuration and my preferred configuration which is two reducing elbows (I like two reducing elbows because it saves a weld (while making four welds DN400 instead of DN300, the cost savings is probably negligible, but it seems like a more elegant solution).

[bold]David Simpson, PE[/bold]
MuleShoe Engineering

In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual. Galileo Galilei, Italian Physicist

 

[XL83NL]

David, are you able to source reducing elbows? Wow! Never knew theyre even made

 

[pennpiper]

XL83NL,
Where are you?
In the USA you should try here:

http://www.midcoonline.com/Web/Pages/Products/Fittings/Info/CS/Elbow/Reducer.aspx

In other parts of the world there are suppliers also.
Example: Butt weld, Short radius, Reducing Elbows in India

http://www.excelmetal.net/buttweld-asme-b169-reducing-elbow-manufacturer-supplier.html

Sometimes its possible to do all the right things and still get bad results

 

[XL83NL]

NL, Europe. Never had success, though only tried it once. We dont find them in client specs either (usually European clients)

 

[zdas04]

When I need to change pipe diameter, reducing elbow's are my first choice. I once ran an FEA model on a 16X12 (DN400 X DN300) in gas at a Reynold's Number in the 10[sup]8[/sup] range and gained nearly 0.5 psi (3.4 kPa) going from the small end to the large end. Running the same model with reducer and elbow or an elbow and reducer gave me about 1/10 the pressure improvement (and the results were the same with either the DN300 elbow and the DN400 elbow). Since the FEA model didn't handle swirling flow rigorously, I'm not sure how much faith you can put in either result, but the reducing elbow saved a weld.

[bold]David Simpson, PE[/bold]
MuleShoe Engineering

In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual. Galileo Galilei, Italian Physicist

 

[georgeverghese]

K value for splitter tee from the internet - see subsection on Tee components (below table 62).Also make the necessary rho- Δ(V[sup]2[/sup]/2) correction for each exit stream in to the total dp for each stream.

https://www.suezwaterhandbook.com/f...es-in-the-pipelines-fittings-valves-for-water

So what do you get as total pressure drop for each run, and is this acceptable ?

Note that the K value is typically used with a constant friction factor corresponding to turbulent flow in a non viscous stream, regardless of the actual stream Reynolds number Nre (for example the Darcy friction factor for DN300 pipe is always taken to be 0.013 - see table on page A-26 of Crane TP410M - year 2009 edn).

 

[Prototyp]

Thanks for help.

Doesn't seem to be too bad. We will see during operation if it works out well.