HDPE pipe thickness
HDPE pipe thickness
(OP)
Hello all,
I am working on a water project of which the design does not make sense to me, I need a technical justification if some could please help. The problem is that the spring feeding the plant is located in a mountain about 400 meters above, and 2.4 Km away as in the drawing, and the designer from the catchment to the plant put six Pressure reducing valves in series to the plant, the pipe is HDPE 110mm PE 100 pipe, the flow is about 7 l/s. At around every drop of 70 meters he has a PRV. This does not make sense, since the other side will be a plant and some water will be used or we could put a surge vessel on the end. Why is the designer taking that the bottom of the line will be at 40 bars and he needs all these prv's why not install a pressure relief valve on the end and dispose of all the prv's?
Your help is highly valuable since the final design will be finalized soon. The cost of the this design is quite big for the budget of the community.
best regards,
I am working on a water project of which the design does not make sense to me, I need a technical justification if some could please help. The problem is that the spring feeding the plant is located in a mountain about 400 meters above, and 2.4 Km away as in the drawing, and the designer from the catchment to the plant put six Pressure reducing valves in series to the plant, the pipe is HDPE 110mm PE 100 pipe, the flow is about 7 l/s. At around every drop of 70 meters he has a PRV. This does not make sense, since the other side will be a plant and some water will be used or we could put a surge vessel on the end. Why is the designer taking that the bottom of the line will be at 40 bars and he needs all these prv's why not install a pressure relief valve on the end and dispose of all the prv's?
Your help is highly valuable since the final design will be finalized soon. The cost of the this design is quite big for the budget of the community.
best regards,





RE: HDPE pipe thickness
You don't say what SDR the pipe is (i.e. wall thickness) It makes quite a difference, but judging by your designer I would hazard a guess the max working pressure of the pipe is about 10 bar ( PE100 has a maximum of 16 bar at its thickest rating )
By PRV I assume you mean Pressure Regulating Valve?? (It can also mean Pressure relief valve). Also that what the valve is doing is limiting the pressure in the downstream pipe to something like 3 bar??
Your designer is working on the basis that at some point someone at the base of the pipe could either turn it off or reduce the flow rate from the maximum flow. In either of those circumstances the pressure in the pipe would rise to well above the pressure rating of the pipe which could cause it to bulge or break.
Yes you can eliminate them, but then your only flow control or on/off needs to be at the top, you need to have NO possibility of blockages, i.e. NONE EVER?? and NO valves whatsoever on the pipeline until it empties into an open pond. If you can do this / guarantee this then yes, remove the Pressure regulating valves.
The problem is you build it that way, go away and then someone who doesn't understand this fits a valve at the end because he doesn't want to walk / cycle / ride / drive to the start point 400m up. He then turns it off or throttles it back and then 15 minutes later has water flowing out of a hole in the ground and blames you for building a shoddy pipe.
Pressure regulating valves are not that expensive and most can work on pilots and springs needing no external power. You could always compare the cost to a steel pipe or flexible pipe with a higher pressure rating?
A relief valve at the base is uselsss as the flow would need to be the same as if the end valve was fully open, ditto P Relief VS along the line would simply open up full bore until you could turn off the start valve.
does that help?
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RE: HDPE pipe thickness
That would solve all your problems - just put a weir at the top and flow it like a small stream?
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: HDPE pipe thickness
David Simpson, PE
MuleShoe Engineering
In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual. Galileo Galilei, Italian Physicist
RE: HDPE pipe thickness
For maintenance purposes, it makes more sense to reduce the number of PRV's and increase the pipe wall thickness. You are correct, it may be possible to eliminate all of the PRV's except one.
There should not be a large difference in project cost for either alternative.
RE: HDPE pipe thickness
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: HDPE pipe thickness
RE: HDPE pipe thickness
RE: HDPE pipe thickness
So thanks again for all the inputs God bless
RE: HDPE pipe thickness
As for a given design delivery/flow quantity involved for the pipeline the flow velocity is proportional to the inverse of the inside diameter squared, this means a MUCH higher required flow velocity for the proposed pipe (and with any concomitant effects therefrom).