×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Velocity vs. Discharge Piping Diameter
2

Velocity vs. Discharge Piping Diameter

Velocity vs. Discharge Piping Diameter

(OP)
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?

RE: Velocity vs. Discharge Piping Diameter

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.  

RE: Velocity vs. Discharge Piping Diameter

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.

RE: Velocity vs. Discharge Piping Diameter

(OP)
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?

RE: Velocity vs. Discharge Piping Diameter

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

RE: Velocity vs. Discharge Piping Diameter

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

Katmar Software
Engineering & Risk Analysis Software
http://katmarsoftware.com

RE: Velocity vs. Discharge Piping Diameter

(OP)
Warman flanges are oversized.  

RE: Velocity vs. Discharge Piping Diameter

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

RE: Velocity vs. Discharge Piping Diameter

(OP)
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.

RE: Velocity vs. Discharge Piping Diameter

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-publication-getPDF.pdf?PatentNo=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

 

RE: Velocity vs. Discharge Piping Diameter

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?

RE: Velocity vs. Discharge Piping Diameter

(OP)
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,

RE: Velocity vs. Discharge Piping Diameter

for quartz sand, I will choose polyurethane

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources