4 replies to this topic

[beeone]

Hi

 

I'm a student doing a final paper that includes calculating the pressure losses. I chose Darby's 3-K method and I have a really stupid question. What does r/D mean in charts in tee section. I totally get R/D at elbows, but here I don't get it. A d/D would be understanding, but r/D doesn't.

 

And if is not too much trouble, I'm in dilemma what to choose threaded or flanged if all fittings are welded to the pipes.

 

Please help me, because my professor is a little old school and didn't heard for this method yet so he hasn't got a clue, either.

[breizh]

http://neutrium.net/...-length-method/

 

Consider this link it could help ! 

 

Don't worry we are not too old to learn good engineering practices

 

 

Breizh

Edited by breizh, 13 August 2013 - 04:54 AM.

[beeone]

Thank you for this. I was looking this site earlier. It is really nice and you can find good explanations even for those of us whose english isn't the first language.

 

But I got a little bit more confusing as I started to think a little more about this problem.

 

I will just lay it out. My project is a district heating network with welded steel pipes. Which coefficients do I choose for tees (stub in a branch, threaded, flanged), and the same for elbows. Branches in tees are welded at an angle of 90° on the main pipe and often they are smaller. Must I use different coefficients for different sizes of are all the same?

 

Lp

Blaž 

[katmar]

You will find illustrations of the flow paths through tees at http://www.katmarsof...lo-fittings.htm

 

If a pipe is welded directly into another pipe at 90 degrees then that is called a "stub-in" - although you will find other terminology used around the world.  This is not accepted by most codes for pressure piping and a properly formed tee would be welded into the lines.  The "r" you spoke of for tees is the radius of the connection from the run to the branch.  It is exactly the same idea as for elbows, but of course comes from both sides.

 

The K values for tees do vary with size (and with flow).  The 3-K method you mentioned will calculate this effect.

[beeone]

This is exactly what i was looking for.

Thank you katmar. 

 

Lp

Blaž