Pumps replaced on cement slurry projects

In China, specially equipped engineering boats (about the size of small tugs) are fitted with concrete-carrying silos or holds. The boats ferry between tidal, pile-driving and quayside construction sites to deliver concrete grouting in line with project requirements.

Earlier this year, Watson-Marlow Fluid Technology Group (WMFTG) China secured five orders comprising a total of 90 Bredel heavy-duty hose pumps required for a €1.8 million series of new grouting projects performed in seas around the Chinese coastline. Including Bredel 65 and Bredel 80 models, the pumps will be installed across six engineering boats (15 pumps aboard each vessel). The pumps were ordered for drawing the abrasive cement/sand/water slurry from the mixing tanks into the holds of the seafaring vessels and for metering the grouting accordingly.

The pumps were selected in place of piston pumps, which on previous grouting projects created issues such as fluid leakage, component wear and unplanned maintenance. WMFTG got the opportunity to supply a Bredel pump for trial, which proved that Bredel technology could overcome the leakage and wear problems. This reduced costs through greater uptime; reduced the need for maintenance and spare parts; and helped create a safer working environment.

The reason that the previous piston pumps struggled was the abrasive nature of the cement, sand (8%) and water mix (0.7 water-to-cement ratio). Discharged into the pile driver at pressures of over 10 bar, conventional pumps are subjected to continual wear problems. In Bredel pumps, nothing but the hose touches the fluid. This means that the only wear part is the hose, which can be quickly and easily replaced if required. As a result, Bredel is suitable for all slurries, as well as viscous, shear-sensitive or aggressive fluids.

The larger Bredel 80 models used on the grouting projects draw the slurry from the mixing tanks into the hold at 330 L/min. These pumps run for approximately 2 h periods at 29 rpm. The smaller Bredel 65 pumps, which meter the grouting, run for the same amount of time (at 30 rpm), at a flow rate of 200 L/min. The running time of the pumps is controlled automatically via a PLC.

WMFTG has already delivered 30 Bredel pumps for the first two engineering boats, and another 60 pumps are in production and will follow shortly.