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2016FallShotcreteEMag

Technical Tip or worn hoses, and Option 1 may put this job beyond the capabilities of this pump. Conversely, in Option 2, using mostly steel line and a minimal length of hose, the pumping pressure will be under 500 psi (3.5 MPa). The reduction in pumping pressure achieved by using steel pipeline will result in significant cost savings due to reduced fuel consumption; reduced wear and tear on the pump; and reduced abrasion on the wear parts in the pump, pipeline, and hose. The lower pressures will allow the pump to provide a smoother flow through the line, easing the physical demands on the nozzleman (Fig. 4 and 5). Using steel pipeline instead of hose also allows this smaller pump to be used on longer pushes, avoiding the expense of a higher-pressure pump that would be required if you were using hose alone. The Brass Tacks Using steel pipeline in place of hose is not only easier on your equipment but also on your bank account. When comparing equal lengths of steel pipeline and hose, the pipeline will cost less than the hose, even after including several elbows and the extra couplings. The steel pipeline can also be expected to outlast the rubber hose in terms of volume pumped and surviving handling and damage at the jobsite. Steel pipe can tolerate a little rough handling that would kink or tear up the protective jacket of a hose. In cases of a plug, shorter lengths of pipe are easier to handle and clean out. Lower up-front cost, in addition to more volume pumped, is a double win for the pumper. Of course, rubber delivery hose is necessary in concrete pumping and especially wet-mix shotcrete placement. The flexibility of hose just can’t be matched by steel pipeline. Hopefully, the benefits of lower pumping pressure, less wear and tear on pumping equipment, less fuel consumption, lower purchase price, and longer expected lifespan all outweigh that lack of flexibility. With these benefits in mind, I hope you will consider sending your truck or trailer out to the next job with a little less hose and a little more steel pipe. Andy Kultgen is an Engineer at Construction Forms, Inc., based in Port Washington, WI. Since 2011, he has been involved in research and development as well as technical and field engineering for the concrete pumping and mining industries. He has worked on customized products and layout plans for concrete pumping on several record-setting projects in the United States and around the world. Kultgen received his BS specializing in machinery systems engineering from the University of Wisconsin, Madison, WI. He is active in ASA and ACI, and is focused on furthering research in wet-mix nozzle performance and developing improved nozzle designs, as well as encouraging safe practices in the concrete pumping industry. Fig. 4: The pump operator monitors the pipeline during priming. Using steel pipe enabled this mixture to be pumped at lower pressures Fig. 5: Using hose only, this pump was pressuring out at 4600 psi (32 MPa) in the hydraulic system, or 1130 psi (7.8 MPa) on the concrete. Replacing 50 ft (15 m) of hose with pipeline lowered pressure to 3400 psi (23 MPa) in the hydraulics, or 835 psi (5.8 MPa) on the concrete 34 Shotcrete • Fall 2016


2016FallShotcreteEMag
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