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2014SprShotcreteEMag

Safety Shooter Hose Selection and Safety in Concrete Pumping By Andy Kultgen T shotcrete application, and because of the the liner, and the ends.are laying out the hose at the beginning of a job,and there are three areas to check: the outer jacket,here are many options for hoses to use forthe concrete pumping portion of wet-process high working pressures involved and the limited Any damage to the reinforcing plies (either life span of all hoses, each member of the shot- wire or fabric) will severely reduce the ability of crete team should be aware of the limitations of the hose to withstand pressure. The outer jacket the hose they are working with and keep alert for of the hose is there to protect the reinforcing plies the signs of impending failure. from the typical nicks, scrapes, and gouges expe- Safe concrete pumping begins with hose selec- rienced on the job site. When examining the cover, tion to meet the job requirements. The American pay close attention to bulges, kinks, soft spots, Concrete Pumping Association recommends cuts, or abraded areas, which may indicate broken using a hose no less than three times and prefer- or displaced reinforcement. If the hose cover has ably four times the diameter of the largest aggre- been damaged to the point where the reinforcing gate in your mixture. Knowing what pump you plies are visible, the hose must be either discarded are using, and particularly the maximum pressure or returned to the factory for the damaged area to this pump is capable of producing, will dictate be removed (Fig. 2). what type of hose you will need. Many pumps Hoses with areas where the liner is excessively commonly used for shotcrete work can produce worn must be discarded. Typically, the first 1 to up to 1000 psi (7 MPa) of pressure on the con- 2 ft (0.3 to 0.6 m) from the end of the hose is the crete; however, there are pumps capable of highest wear area for the liner. However, smaller- exceeding 2000 psi (14 MPa) at the concrete diameter hoses are often difficult to inspect, even piston face. Every hose should be labeled to with a flashlight. In those applications, some indicate what the maximum working pressure is external clues can predict heavy liner wear. Check for that hose (Fig. 1). Most hoses used in shot- crete work are rated between 500 and 1300 psi (3.5 and 9.0 MPa). If your pump is capable of producing a greater concrete pressure than your hose is rated for, you must switch to a hose with a higher rating or a pump with a lower maximum pressure on the concrete. A plug in the hose or at the nozzle can result in a nearly instantaneous spike to the pressure limit at the pump, possibly resulting in a catastrophic failure of a hose. Ensuring the pump pressure will not exceed the pressure rating of the hose and couplings is of utmost importance to the safety of everyone working near the pump, hoses, and nozzle. The rugged nature of the job site environment, including loading and unloading frequently and being dragged across gravel and exposed rein- forcing bar, can quickly damage a hose, even with proper precautions. This tough working environ- ment necessitates regular inspections to catch any impending failures before they happen. A great Fig. 1: All hoses should be labeled with maximum working pressure. This time to perform a visual inspection is when you hose is labeled for a working pressure of 1250 psi (8.6 MPa) Shotcrete • Spring 2014 35


2014SprShotcreteEMag
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