MechChem Africa March 2017

Better API pumping solutions

Peter Middleton talks toWeir Minerals’ GM for products, Ronald Govender, and dewatering product manager, Kevin Roelofse, about two modern API pumps for the petrochemical industry: the Floway vertical spindle pump for high flow applications and the new WSP Roto-jet, Pitot-tube between- bearings pump for high-head low-flow applications.

“ W e at Weir Minerals are well known in Africa for our mill circuit and slurry pumping solutions, through our Weir Warman and Envirotech brands. We have serviced the mining sector extensively over the years, developing our technology advances and, through mergers, expanded our offering to include awide spec- trumof inter-related, high-quality equipment solutions, such as Trio crushers, mill liners, cy- clones, valves, piping and rubber and ceramic wear solutions,” begins Govender. “All of Weir’s development efforts have targeted reduced total costs of ownership – through better reliability and improved uptime – alongwithbetter efficiency, produc- tivity and profitability,” he adds. “What is less well known is our global strength in the petrochemical industry. Weir has a £600-million Oil and Gas business, with a notable presence in the Middle East and considerable expertise in fracking, for example. Included in this offering are several API compliant pump brands that, between them, cover a very wide spectrumof needs in the petrochemical and oil and gas industries,” Govender tells MechChem Africa . “We see niche opportunities in Africa for two of our API pump ranges: our Floway Vertical Turbine Pumps for high flow appli-

cations and our new WSP Roto-Jet Pitot-tube pumps, which offer sig- nificant advantages in high-pressure low-flow applications,” he reveals. Describing the different require- ments for pumping petroleum, hy-

Kevin Roelofse and Ronald Govender.

drocarbon or chemical products, Roelofse says that, due to their explosive and/or hazardous nature, product leakage is 100% unacceptable, so double mechanical seals, along with their auxiliary flushing and pres- surising systems, are always required. “These products are often pumped hot, so thermal expansion rates have to be taken intoaccount. Shaft flexing andpumpvibration levels must be minimised to avoid premature damage to themechanical seals andbearings; hydrocarbon products have a low specific gravity, so the suction pressure (NPSH) has to be raised; and low vapour pressure means that higher pumping pressures are needed to avoid cavitation. “The requirements for pumps in thepetro- leum industry are specified inAPI 610 andwe are now at Revision 11,” says Roelofse. “The standard specifies six governing criteria, and if any apply, then a pump compliant to the API standard shouldbe considered,” he notes. Floway vertical turbine pumps Made in Fresno California, Weir Minerals’ Floway VHP series pumps are compli- antwith the current API 610 standard. “They are classified as VS (vertical spindle) pumps and Weir has several of the API plans in its range. “Floway VHP VS6 pumps are now draining an oily water sump at a local refinerypumpinghydrocarbons,forex- ample. These pumps have their spindle enclosed in a can or bowl about 6.5 m deep, with the inlet above. This creates additional head, raising the trueNPSH by increasing the vertical column length in the can,” Roelofse explains. “Our VHPVS1 pumps, on the other hand, have an open spindle, which means that the liquid level in the tank or sumpmust always bekept above the top of the spindle to ensure adequate suction pressure,” he tells MechChem Africa .

“We also have six non-API Floway pumps being used to extract condensate from a power station in Zimbabwe. The condensate water is at 60 to 65 °C, so it is prone to va- porisation and cavitation. The vertical spindle arrangementwith its raised column increases the head on the suction side, helping to over- come this problem,” he adds. “Floway VTPs are also ideal for water transport and, in the US, these pumps are much more commonly used than split-case horizontal pumps. Here, we have them in- stalled in mining pontoons for pond water transfer, for example, where sophisticated API features such asmechanical seals are not needed. They are a more cost-effective op- tion in this application than using centrifugal pumps with high-level specs and a big impel- lers,” he notes. The WSP Roto-Jet One of the original developers of the Pitot- tube pump was Tom Maceyka, now a Weir employee, who was largely responsible for getting the technology added to API 610. “The principle is not new. It has been widely adopted in the global petrochemical industry for high-pressure, low-flowapplications,” says Roelofse. “What is new is our WSP Roto-Jet type BB6, which is a pump suspended between bearings, unlike original designs that were overhanging. This ensures better shaft rigid- ity, less vibration, longer seal and bearing life and it enables these high-pressure pumps to comply with every criteria listed in the API specification,” he continues, adding that almost all other API pumps have deviations of some sort or another. Pitot tube pumps compete directly with high-speed centrifugal pumps, which have to operate at 24 000 rpm to achieve the head and flow requirements. “Our Roto-Jets have an integral gearbox that enables them to run at6000rpm.Thepumpscantypicallyproduce 1 550 m heads, which is extremely high for

The installation of a Floway vertical turbine pump on a Multiflo barge.

18 ¦ MechChem Africa • March 2017