Proper/Allowable use of Flex Hose? 1

[lookintomyeyes]

I am designing a piping layout to replace the existing piping for dimineralized water heat exchangers. I need to connect the demin water inlet and outlet headers to allow the heat exchangers to be bypassed, however the elevations of the two headers are different by just over 1".

I have seen flexible (braided) hose used to align piping with pumps, can it also be used to connect these two headers? I'm currently thinking yes, but am wondering if there are other design considerations I am overlooking.

Also, I am having trouble finding manufacturers of 8" flex hose - can anyone provide a possible supplier name?

Thank you in advance for your thoughts and patience,
A new Engineer-in-Training, with just over 1 year experience

 

[scastillo]

Check with Sani-Tech or possibly Saint-Gobain, they offer a Fluoropolymer lined SST braided hose that goes up to 7.80" ID. Note that the min bend radius is listed at 84".

 

[Ashereng]

Does your site's piping standards allow flexible hoses?

"Do not worry about your problems with mathematics, I assure you mine are far greater."
Albert Einstein
Have you read FAQ731-376 to make the best use of Eng-Tips Forums?

 

[BriK]

I don’t think I have ever seen flex hose of that size, duct perhaps...4" is about the max I have ever used for flex hose and that was by Rubberfab...

One point I would make about flex hose...if its corrugated, be very careful about performance...most corrugated flex has an optimum flow direction as both sides are typically not identical (different slopes and lengths in each side of a corrugation) and you get poor performance if you run it backwards, believe it or not...I learned this the hard way and actually had to swap the corrugated tube out for smooth bore flex tube...

 

[lookintomyeyes]

Thank you for your responses.
I am thinking perhaps flex hose is not the best option for this project - it may simply be easier to cap both lines and construct a bypass line to connect the two.

 

[Yorkman]

lookintomyeyes,
I'm a pipefitter by trade and have been faced with this type of problem many times. Generally I just construct an offset using weld pipe to the offset dimension.
I don't know the skills of the people you're working with but it isn't that hard. Your offset angle using a standard L.R.weld fitting would be 16.597[°]The advance of the offset face to face before adding any flanges would be 6.855 inches. I have a web site that will calculate many types of offsets (free) it might be helpful.

http://home.comcast.net/~offsetaj

I'm not a real engineer, but I play one on T.V.
A.J. Gest, York Int./JCI

 

[lookintomyeyes]

Thanks Yorkman - I knew this type of problem likely occurred in industry and was hoping someone could tell me how they cured it.
Would you by any chance be able to provide a sketch? I -think- I am visualizing it correctly, but a picture would definitely help.

Unfortunately my company has blocked yoru link, so now I have to phone internet security to see if they can unblock it for me...

 

[JLSeagull]

Refinery delayed cokers use 10,000 psi API drilling hose for the high-pressure high-volume coke cutting flow. I think that the size is about 6-inch. I don't know the maximum drilling hose size.

 

[Galuck]

Flexible metal hose should work for this type of application. For 8", I would suggest calling Twin City Hose. They can be reached at

http://www.twincityhose.com

 

[Yorkman]

I've tried to insert the drawng but was not able. If you could check out the site at home or at some non secure site, here's how to get to the offset I was describing.
1. Enter the site, you may have to allow pop ups.

http://home.comcast.net/~offsetaj

2. On the left is a navigation index click on offset selection cart
3. Enter the selection chart skip the tutorial
4. Select the type of offset (Parallel: fitting to fitting)
5. Follow the promter and enter the data. The sketch is roughly the type of offset you're looking at although the angle is far steeper.
6. This is a personel website so some of the decimal places tend to run long.
The angle and dimensions I quoted were based on a 1 inch offset if you give me the exact dimension it wouldn’t be any problem to give you exact dimensions and some layout dimensions as well. (Example the throat and heel arc lengths and the centerline references).

There is also a page on the site that will guide you on how to layout the fitting and how to fit it up so the angle of the offset is correct. The GANG Box has most of the information, you might also check out the Fitting Layout page. Good Luck

I'm not a real engineer, but I play one on T.V.
A.J. Gest, York Int./JCI

 

[MikeHalloran]

So far the problem statement does not include a design pressure.



Mike Halloran
Pembroke Pines, FL, USA

 

[lookintomyeyes]

Thank you Yorkman, this is an excellent alternative to what I was trying to accomplish with the flex hose, and made me realize that I would've been better posting to ask how to deal with offset pipes, rather than for info on a solution that likely not the only solution.
(I'll have to remember that for next time, to ask what the REAL question is.)

 

[thalon]

Don't additional tests need to be done when using modified or custom fittings? By cutting the elbow as you've suggested the elbow would no longer be covered under B31.3 as a standard fitting. So the onus is now on the owner of the system to prove that the piping is safe.

Please correct me if I'm wrong.

 

[Yorkman]

The systems that I've modified these fittings on are on hydronic systems in nature, chilled water, hot water, condenser water. The operating pressures have been under 250 psig. Usually it was a retrofit were we removed one piece of equipment and installed another, and hand to make connections below an isolation valve with very little room for fiitings. The systems were pressure tested to meet a city/state inspector, as to being covered under a B31.1 standard I can't say. I will say it is a common practice in the heating and cooling industy, when retrofitting in new equipment to an existing piping system, but you do bring up a valid point.

I'm not a real engineer, but I play one on T.V.
A.J. Gest, York Int./JCI

 

[bigskyguy]

check out metraflex and romac industries, they build rotating ball flexes as well in large diameters.