There’s a wheel barrow in my pipeline!

Rob Welke, from Adelaide, South Australia, took an unusual cellphone from an irrigator in the late 1990’s. “Rob”, he said, “I think there’s a wheel barrow in my pipeline. Can you locate it?”
Robert L Welke, Director, Training Manager and Pumping/Hydraulics Consultant
Wheel barrows have been used to carry equipment for reinstating cement lining throughout mild steel cement lined (MSCL) pipeline building within the outdated days.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 happened through the rehabilitation of the Cobdogla Irrigation Area, near Barmera, South Australia, in 1980’s. It is also suspected that it might simply have been a believable excuse for unaccounted friction losses in a brand new 1000mm trunk main!
Rob agreed to help his client out. A 500mm dia. PVC rising major delivered recycled water from a pumping station to a reservoir 10km away.
The problem was that, after a 12 months in operation, there was a couple of 10% reduction in pumping output. The client assured me that he had examined the pumps they usually were OK. Therefore, it just had to be a ‘wheel barrow’ within the pipe.
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Rob approached this downside a lot as he had during his time in SA Water, the place he had extensive expertise locating 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 multiple areas (at least 10 locations) which had been surveyed to offer correct elevation data. The sum of the stress reading plus the elevation at each level (termed the Peizometric Height) gave the hydraulic head at each level. Plotting the hydraulic heads with chainage offers a a number of point hydraulic gradient (HG), very like in the graph below.
Hydraulic Grade (HG) blue line from the friction tests indicated a consistent gradient, indicating there was no wheel barrow in the pipe. If there was a wheel barrow within the pipe, the HG would be like the red line, with the wheel barrow between points three and four km. Graph: R Welke
Given that the HG was pretty straight, there was clearly no blockage along the way, which would be evident by a sudden change in slope of the HG at that time.
So, it was figured that the top loss should be due to a general friction build up within the pipeline. To verify this principle, it was decided to ‘pig’ the pipeline. This concerned using the pumps to pressure two foam cylinders, about 5cm larger than the pipe ID and 70cm long, along the pipe from the pump end, exiting into the reservoir.
Two foam pigs emerge from the pipeline. The pipeline performance was improved 10% as a result of ‘pigging’. Photo: R Welke
The immediate improvement in the pipeline friction from pigging was nothing in need of superb. The system head loss had been nearly completely restored to original performance, leading to a few 10% move improvement from the pump station. So, as a substitute of discovering a wheel barrow, a biofilm was discovered responsible for pipe friction build-up.
Pipeline performance can be always be viewed from an vitality 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 because of biofilm brought on the pumps not only to operate at a better head, however that a variety of the pumping was pressured into peak electricity tariff. The reduced efficiency pipeline finally accounted for about 15% additional pumping energy prices.
Not everyone has a 500NB pipeline!
Well, not everyone has a 500mm pipeline in their irrigation system. So how does that relate to the common 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 12 months. เกจ์อาร์กอนsumo : R Welke
PVC pipe has a Hazen & Williams (H&W) friction worth of about C=155. When decreased to C=140 (10%) via biofilm build-up, the pipe may have the equal of a wall roughness of zero.13mm. The identical roughness in an 80mm pipe represents an H&W C worth of one hundred thirty. That’s a 16% discount in flow, or a 32% friction loss increase for the same flow! And that’s simply in the first year!
Layflat hose can have high vitality value
A living proof was noticed in an power efficiency audit carried out by Tallemenco lately on a turf farm in NSW. A 200m lengthy 3” layflat pipe delivering water to a delicate hose increase had a head lack of 26m head in contrast with the producers score of 14m for a similar move, and with no kinks in 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 sizzling solar all summer season, breeding these little critters on the pipe inside wall.
Calculated when it comes to energy consumption, the layflat hose was liable for 46% of total pumping energy prices via its small diameter with biofilm build-up.
Solution is larger pipe
So, what’s the solution? Move to a bigger diameter hose. A 3½” hose has a new pipe head lack of only 6m/200m on the same move, however when that deteriorates as a outcome of biofilm, headloss could 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 power 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 instances, the pump might have to be changed out for a decrease head pump.
Everyone has a wheel barrow in their pipelines, and it only gets larger with time. You can’t do away with it, however you presumably can management its effects, both by way of power efficient pipeline design in the first place, or attempt ‘pigging’ the pipe to eliminate that wheel barrow!!
As for the wheel barrow in Rob’s client’s pipeline, the legend lives on. “He and I nonetheless joke concerning the ‘wheel barrow’ within the pipeline when we can’t explain a pipeline headloss”, mentioned Rob.
Author Rob Welke has been 52 years in pumping & hydraulics, and never bought product in his life! He spent 25 yrs working for SA Water (South Australia) within the late 60’s to 90’s where he carried out in depth pumping and pipeline power effectivity 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 clients Australia wide.
Rob runs common “Pumping System Master Class” ONLINE training programs Internationally to pass on his wealth of knowledge he realized from his fifty two years auditing pumping and pipeline methods throughout Australia.
Rob can be contacted on ph +61 414 492 256, or email . LinkedIn – Robert L Welke