MechChem Africa March 2017

MechChem Africa

•

March 2017

“

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-

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

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.

Kevin Roelofse and Ronald Govender.

The installation of a Floway vertical turbine pump on a

Multiflo barge.

Better API pumping solutions

“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