Velocity vs. Discharge Piping Diameter 2

[Ork1]

I am using several 8x6 Warman slurry pumps with closed impellers. My discharge piping is 8" and 10" but I have a 6" spool piece fastened to the volute/case and a concentric that fits up to 8" or 10" respectively (6"x8" concentric). What changes would occur if I just came off the pump with an 8" spool and eliminate the concentric? If it is not recommended; how long does the 6" spool piece need to be? How does this effect velocity?

 

[Artisi]

How are you going to make the transition from 6 to 8 / 6 to 10 without some type of spool piece and what is wrong with the concentric you currently have.

 

[micalbrch]

The effect of the concentric itself is negligible in terms of head. But if you want to change the following pipeline from 10" to 8" you will have an effect.

 

[Ork1]

I can fabricate a discharge spool to eliminate the concentric which often fails prematurely. What is the requirement or rule of thumb for keeping the same diameter off of the volute or case. Can I fasten an 8" spool directly to the case of the pump or will that effect the velocity too much?

 

[Artisi]

Just bolt whatever you like to the discharge flange - you wouldn't be able to measure any difference regarding losses etc..

 

[katmar]

How do you bolt an 8" diameter spool to a 6" flange without a reducer?

Katmar Software
Engineering & Risk Analysis Software

http://katmarsoftware.com

 

[Ork1]

Warman flanges are oversized.

 

[saplanti]

Did you investigate the reason of the premature fealure of the discharge spool?

Warman pumps have very small allowable external loads by comparing with the piping allowable. I guess in your case the piping introduces some kind of loading that pump and piping can resist but the spool fails.

In the pipe stress analysis this spool peace should be taken into consideration and provide reasonable supports and flexibility in the piping the eliminate the failure in the spool. At the moment spool peace is working as stress reliever or safety equipment in the piping. If you take it off and attach the piping onto the pump flange you need to deal with pump flamge allowables as well as the weak connection in your proposal.

I suggest do you pipe stress analysis by considering the concentric spool and keep the stresses in the spool within the code allowable and additionally check the flange connections for strength and leakage. So you would not have any more problem.

Kind regards,

Ibrahim Demir

 

[Ork1]

Saplanti,
Thank you; I am using 8" Goodall Hose for piping and it is well supported. I have rubber lined steel pipe for spools/concentric, and I am pumping a very course slurry with high concentrates of quartz. Very abrasive material. My pipe connections are victaulic which in itself, if not properley installed, will fail sooner than later. I want to eliminate that fitting{concentric} without decreasing the pumps performance hence, fabricate a straight 8" spool off the pump directly to the Goodall bolt-up flange.

 

[saplanti]

So the wear is the problem. Have you tried changing the material of rubber lining to another material (Ni-Hard IV or ceramic lining) to reduce the wear effect. Or replacing the rubber lined spool by entirely Ni-Hard IV spool. That may be extending the replacement period substantially.

In case you eliminate the spool, and connected flange does not meet the pump flange dimensions (PCD and bolt sizes) you had better get Warman's approval for what you are doing. Sketching your idea is going to cut a lot of discussion I guess.

Additionally I suggest you look at the following link, may be helping you in the process:

http://ns3.patent.gov.uk/p-find-pub...tentNo=GB2464594&DocType=A&JournalNumber=6310

If you use the matching flange with the idea given in this document, everthing will be perfect. However, finding a company to make use this idea may not be easy, I guess.

Regards,

Ibrahim Demir

 

[micalbrch]

Agree with Ibrahim if wear is a problem. Rubber lining is better for fine tailings than for course material. For course material hard alloys are the better option.

Have you ever tried an eccentric spool piece instead of the concentric one?

 

[Ork1]

Thank You Ibrahim, Micalbrch,
Very interesting coupling, I can think of many piping arrangements that would benefit from this. I did speak with a Warman rep. and he had no objections with bolting an 8" line to the 6" discharge flange however, I also seek the advice of this forum for more in depth discussions. Ni-Hard is truly the way to go! and I will follow up on both.

Thank You All,

 

[SlurryPumps01]

for quartz sand, I will choose polyurethane