There’s a wheel barrow in my pipeline!

Rob Welke, from Adelaide, South Australia, took an unusual telephone from an irrigator in the late 1990’s. “Rob”, he said, “I think there’s a wheel barrow in my pipeline. Can you find it?”
Robert L Welke, Director, Training Manager and Pumping/Hydraulics Consultant
Wheel barrows have been used to carry kit for reinstating cement lining throughout mild steel cement lined (MSCL) pipeline building within the previous 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, close to Barmera, South Australia, in 1980’s. It can additionally be suspected that it could simply have been a plausible excuse for unaccounted friction losses in a model new 1000mm trunk main!
Rob agreed to help his shopper out. A 500mm dia. PVC rising main delivered recycled water from a pumping station to a reservoir 10km away.
The drawback was that, after a 12 months in operation, there was a couple of 10% discount in pumping output. The client assured me that he had examined the pumps they usually have been OK. Therefore, it just had to be a ‘wheel barrow’ in the pipe.
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Rob approached this downside much as he had throughout his time in SA Water, where he had intensive 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 strain readings alongside the pipeline at a quantity of areas (at least 10 locations) which had been surveyed to provide accurate elevation information. The sum of the strain reading plus the elevation at each point (termed the Peizometric Height) gave the hydraulic head at each point. Plotting the hydraulic heads with chainage offers a a number of level hydraulic gradient (HG), much like within the graph below.
Hydraulic Grade (HG) blue line from the friction exams indicated a constant gradient, indicating there was no wheel barrow in the pipe. If there was a wheel barrow in the pipe, the HG would be like the red line, with the wheel barrow between factors 3 and 4 km. Graph: R Welke
Given that the HG was fairly straight, there was clearly no blockage along the way, which would be evident by a sudden change in slope of the HG at that point.
So, it was figured that the top loss should be due to a common friction construct up in the pipeline. To affirm this theory, it was decided to ‘pig’ the pipeline. This concerned using the pumps to drive two foam cylinders, about 5cm larger than the pipe ID and 70cm long, alongside the pipe from the pump end, exiting into the reservoir.
Two foam pigs emerge from the pipeline. The pipeline performance was improved 10% on account of ‘pigging’. Photo: R Welke
The instant improvement within the pipeline friction from pigging was nothing short of wonderful. The system head loss had been nearly completely restored to original performance, leading to about a 10% move enchancment from the pump station. So, instead of discovering a wheel barrow, a biofilm was discovered liable for pipe friction build-up.
Pipeline performance may be all the time 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 improve in system head as a outcome of biofilm caused the pumps not only to function at a higher head, but that some of the pumping was pressured into peak electricity tariff. The lowered efficiency pipeline in the end accounted for about 15% additional pumping energy prices.
Not everyone 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. เกจ์วัดแรงดันน้ำมันเครื่อง (broken) exhibits system curve after pigging. Biofilm raised pumping costs by up to 15% in a single 12 months. Graph: R Welke
PVC pipe has a Hazen & Williams (H&W) friction worth of about C=155. When reduced to C=140 (10%) by way of biofilm build-up, the pipe will have the equivalent of a wall roughness of 0.13mm. The identical roughness in an 80mm pipe represents an H&W C value of a hundred thirty. That’s a 16% discount in circulate, or a 32% friction loss enhance for the same flow! And that’s simply within the first year!
Layflat hose can have excessive vitality value
A living proof was noticed in an vitality efficiency audit carried out by Tallemenco just lately on a turf farm in NSW. A 200m long 3” layflat pipe delivering water to a soft hose boom had a head lack of 26m head in contrast with the producers score of 14m for a similar circulate, and with no kinks within the hose! That’s a whopping 85% enhance in head loss. Not stunning contemplating that this layflat was transporting algae contaminated river water and lay within the hot solar all summer, breeding those little critters on the pipe inside wall.
Calculated by way of energy consumption, the layflat hose was responsible for 46% of whole pumping vitality prices via its small diameter with biofilm build-up.
Solution is larger pipe
So, what’s the solution? Move to a larger diameter hose. A 3½” hose has a model new pipe head lack of only 6m/200m on the identical flow, but when that deteriorates because of biofilm, headloss might rise to only about 10m/200m as a substitute of 26m/200m, kinks and fittings excluded. That’s a possible 28% saving on pumping energy costs*. In terms of absolute vitality consumption, if pumping 50ML/yr at 30c/kWh, that’s a saving of $950pa, or $10,seven hundred over 10 years.
Note*: The pump impeller would must be trimmed or a VFD fitted to potentiate the energy savings. In some circumstances, the pump may have to be changed out for a decrease head pump.
Everyone has a wheel barrow in their pipelines, and it solely will get larger with time. You can’t eliminate it, but you can control its effects, either through energy efficient pipeline design in the first place, or strive ‘pigging’ the pipe to do away with that wheel barrow!!
As for the wheel barrow in Rob’s client’s pipeline, the legend lives on. “He and I nonetheless joke in regards to the ‘wheel barrow’ within the pipeline once we can’t clarify a pipeline headloss”, stated Rob.
Author Rob Welke has been fifty two years in pumping & hydraulics, and never bought product in his life! He spent 25 yrs working for SA Water (South Australia) in the late 60’s to 90’s where he performed intensive pumping and pipeline vitality effectivity monitoring on its 132,000 kW of pumping and pipelines infrastructure. Rob established Tallemenco Pty Ltd (2003), an Independent Pumping and Hydraulics’ Consultancy primarily based in Adelaide, South Australia, serving clients Australia extensive.
Rob runs regular “Pumping System Master Class” ONLINE training courses Internationally to pass on his wealth of knowledge he discovered from his fifty two years auditing pumping and pipeline methods all through Australia.
Rob could be contacted on ph +61 414 492 256, or e-mail . LinkedIn – Robert L Welke

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