There’s a wheel barrow in my pipeline!

Rob Welke, from Adelaide, South Australia, took an uncommon telephone from an irrigator within the late 1990’s. “ Savings ”, he stated, “I assume there’s a wheel barrow in my pipeline. Can you find it?”
Robert L Welke, Director, Training Manager and Pumping/Hydraulics Consultant
Wheel barrows were used to carry kit for reinstating cement lining throughout delicate steel cement lined (MSCL) pipeline building in the old days. It’s not the primary time Rob had heard of a wheel barrow being left in a large pipeline. Legend has it that it occurred through the rehabilitation of the Cobdogla Irrigation Area, near Barmera, South Australia, in 1980’s. It is also suspected that it might just have been a plausible excuse for unaccounted friction losses in a brand new 1000mm trunk main!
Rob agreed to assist his consumer out. A 500mm dia. PVC rising major delivered recycled water from a pumping station to a reservoir 10km away.
The downside was that, after a 12 months in operation, there was a few 10% reduction in pumping output. The consumer assured me that he had tested the pumps and they had been OK. Therefore, it simply had to be a ‘wheel barrow’ in the pipe.
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Rob approached this problem much as he had during his time in SA Water, where he had extensive expertise finding isolated partial blockages in deteriorated Cast iron Cement Lined (CICL) water supply pipelines through the 1980’s.
Recording hydraulic gradients
He recorded accurate stress readings alongside the pipeline at a quantity of areas (at least 10 locations) which had been surveyed to supply accurate elevation info. The sum of the pressure studying plus the elevation at every level (termed the Peizometric Height) gave the hydraulic head at every level. Plotting the hydraulic heads with chainage provides a a number of point hydraulic gradient (HG), very related to in the graph under.
Hydraulic Grade (HG) blue line from the friction checks indicated a consistent gradient, indicating there was no wheel barrow in the pipe. If there was a wheel barrow within the pipe, the HG could be just like the red line, with the wheel barrow between points three and four km. Graph: R Welke
Given that the HG was fairly straight, there was clearly no blockage along the best way, which might be evident by a sudden change in slope of the HG at that time.
So, it was figured that the head loss have to be as a result of a basic friction build up in the pipeline. To confirm this concept, it was decided to ‘pig’ the pipeline. This concerned using the pumps to drive two foam cylinders, about 5cm bigger than the pipe ID and 70cm lengthy, alongside the pipe from the pump end, exiting into the reservoir.
Two foam pigs emerge from the pipeline. The pipeline efficiency was improved 10% because of ‘pigging’. Photo: R Welke
The instant enchancment within the pipeline friction from pigging was nothing in need of wonderful. The system head loss had been almost totally restored to unique efficiency, resulting in a couple of 10% flow improvement from the pump station. So, instead of discovering a wheel barrow, a biofilm was found liable for pipe friction build-up.
Pipeline ENERGY EFFICIENCY
Pipeline efficiency may be at all times be viewed from an energy efficiency perspective. Below is a graph showing the biofilm affected (red line) and restored (black line) system curves for the client’s pipeline, before and after pigging.
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The enhance in system head as a outcome of biofilm brought on the pumps not only to function at the next head, but that a number of the pumping was forced into peak electricity tariff. The lowered efficiency pipeline in the end accounted for about 15% further pumping energy prices.
Not everybody has a 500NB pipeline!
Well, not everybody has a 500mm pipeline of their irrigation system. So how does that relate to the average irrigator?
A new 500NB
System curve (red line) signifies a biofilm build-up. Black line (broken) exhibits system curve after pigging. Biofilm raised pumping prices by up to 15% in one yr. Graph: R Welke
PVC pipe has a Hazen & Williams (H&W) friction value of about C=155. When reduced to C=140 (10%) via biofilm build-up, the pipe may have the equal of a wall roughness of 0.13mm. The same roughness in an 80mm pipe represents an H&W C worth of one hundred thirty. That’s a 16% reduction in move, or a 32% friction loss enhance for a similar flow! And that’s simply in the first year!
Layflat hose can have high power value
A working example was observed in an energy efficiency audit conducted by Tallemenco lately on a turf farm in NSW. A 200m long 3” layflat pipe delivering water to a gentle hose growth had a head loss of 26m head in contrast with the producers rating of 14m for the same circulate, and with no kinks within the hose! That’s a whopping 85% increase in head loss. Not surprising considering that this layflat was transporting algae contaminated river water and lay within the hot solar all summer time, breeding those little critters on the pipe inside wall.
Calculated when it comes to power consumption, the layflat hose was responsible for 46% of whole pumping energy costs via its small diameter with biofilm build-up.
Solution is bigger pipe
So, what’s the solution? Move to a bigger diameter hose. A 3½” hose has a brand new pipe head loss of only 6m/200m on the identical circulate, but when that deteriorates due to biofilm, headloss may rise to solely about 10m/200m as a substitute of 26m/200m, kinks and fittings excluded. That’s a possible 28% saving on pumping vitality costs*. In terms of absolute vitality consumption, if pumping 50ML/yr at 30c/kWh, that’s a saving of $950pa, or $10,700 over 10 years.
Note*: The pump impeller would must be trimmed or a VFD fitted to potentiate the energy savings. In some cases, the pump could have to be changed out for a decrease head pump.
Everyone has a wheel barrow in their pipelines, and it solely gets greater with time. You can’t do away with it, however you’ll be able to management its effects, either via vitality environment friendly pipeline design within the first place, or strive ‘pigging’ the pipe to get rid of that wheel barrow!!
As for the wheel barrow in Rob’s client’s pipeline, the legend lives on. “He and I still joke in regards to the ‘wheel barrow’ in the pipeline once we can’t explain a pipeline headloss”, stated Rob.
Author Rob Welke has been fifty two years in pumping & hydraulics, and by no means offered product in his life! He spent 25 yrs working for SA Water (South Australia) within the late 60’s to 90’s the place he carried out intensive pumping and pipeline energy efficiency monitoring on its 132,000 kW of pumping and pipelines infrastructure. Rob established Tallemenco Pty Ltd (2003), an Independent Pumping and Hydraulics’ Consultancy based mostly in Adelaide, South Australia, serving purchasers Australia wide.
Rob runs common “Pumping System Master Class” ONLINE coaching programs Internationally to move on his wealth of knowledge he discovered from his 52 years auditing pumping and pipeline techniques all through Australia.
Rob can be contacted on ph +61 414 492 256, www.talle.biz or email r.welke@talle.biz . LinkedIn – Robert L Welke
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