Minor Losses - Internal Pipe Stiffener

[PEorl]

Need k value for connecting HDPE to PVC with an internal pipe stiffener and mj restraint system (FM project) to calculate minor losses. We are thinking of assuming reducer and increaser for k value. Do others typically include this connection in their hydraulics and if so what do they use. (We will have about 26 sections and with a k value of 1, it adds about 6 feet of head to TDH at the operating point.) No luck with manufacturer that I called or internet search. Thanks.

 

[PEorl]

Just received this info/dwg from manufacturer -

The Lengths can be either 10” or 7”. As for the OD/IDs, I’d recommend the items below for the Pipe ID you’ve given. The Stiffeners are made with a lead-in taper. This would be the Min ID of the Stiffener and is only the last inch of the Stiffener. This dimension is not controlled so only an Estimate can be provided.

Pipe - 18” HDPE
ID Size - 15.741
Stiffener OD - 15.585
Stiffener Wall Thickness -.25
Stiffener Min ID (Est.) - 14.75

Pipe - 18” C905
ID Size - 17.180
Stiffener OD - 17.00
Stiffener Wall Thickness - .25
Stiffener Min ID (Est.) - 16.25

 

[bimr]

K value of 1 is a reasonable assumption. I would not normally include something as minor as this. This amount of head loss is much less than the margin of error for your system calculations.

 

[PEorl]

Thanks bimr. I appreciate your remarks.

 

[rconner]

Whether or not such devices and minor losses at obviously many locations would cause problems probably depends on a whole lot of factors, including the tolerance amount for head loss in the specific application, how realistic pipe roughness for field application one is assuming for the pipe to begin with, is actual or nominal inside diameter being used, and the minor loss calculation and/or confirming test results etc. being employed a the device.