world pumps articulo revista
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Number 501 June 2008THE INTERNATIONAL MAGAZINE FOR PUMP USERS
in liaison with
A view from the top onenergy and oil & gas
markets
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0262 1762/08 2008 Elsevier Ltd. All rights reserved
Oil and gas
Fluid handling inremote locationsIn the oil and gas industry, reliable pumps can mean thedifference between a fully operating, efficient gas compression
station and a bottleneck on the pipeline. Natural gas pipelinesare often remote, and powering a pump and performingmaintenance can be difficult. Oakley Roberts of Ingersoll Rand,explains the companys innovative solution.
In remote locations where natural gas is
extracted from the earth, interstate
pipelines facilitate its delivery to refineries,
which may be hundreds of miles away. Natural
gas pipelines depend on large engines to
power stations that compress the gas andcontinue its transfer down the pipeline.
Positioned every 40 to 100 miles along the
pipeline, these engines are critical to gas
transfer efficiency. Any engine breakdown
compromises the integrity of the station and
can cause days or even weeks of downtime
and significant financial setback.
Keeping these engines properly lubricated is a
critical application for diaphragm pumps.
Pipeline operators depend on pumps to
circulate oil and coolant through the engines
to maintain optimal efficiency and preventdowntime. When a compression station is
taken offline, pumps prevent the motor from
locking up by ensuring that it is properly
lubricated. This process is also necessary to
pre-lube the motor before a station is put
back into operation. However, compression
station applications often require pumps to
operate in extremely remote areas, creating a
number of obstacles to overcome.
Traditionally, operators have struggled to
implement pumps at compression stations
without a readily available energy source.
Pneumatic pumps require the purchase of an
air compressor, which must also be electrically
powered. Compressed air can be piped to the
location, but this is often exceptionally
expensive. If a pump fails or is performingFigure 1. Interstate pipelines can travel hundreds of miles before reaching a refinery. Natural gas pipelines rely on compression to
propel the gas along, which means a loss in pressure equals reduced efficiency.
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poorly, maintenance costs can also skyrocket.
Staffing a remote location may not be feasible
and it may be days or weeks before a pump
can be brought back online. Because air-
operated pumps require additional machinery,
the risk of damaged or inoperable equipment
is increased.
Environmental surroundings also pose a
threat to pumps in remote locations. Pumpsat compression stations are usually located
outdoors or in small enclosures where they
are subject to weather conditions. Tempera-
ture fluctuations and extreme weather can
wreak havoc on performance. If the materials
of construction are improperly specified,
pumps are subject to corrosion, ultraviolet
degradation, stalling and ice-up. Pumps
operating around natural gas pipelines can
also create a safety hazard when not installed
properly, as fluid moving through the pump
creates an electrical charge that could ignite
a flammable medium like natural gas.
Because of the readily available energy source
present in the pipeline, many compression
stations now turn to a more convenient option
for their fluid transfer needs: natural gas-
operated diaphragm pumps. Instead of
requiring an air compressor and an additional
power source, natural gas-powered diaphragm
pumps create a self-contained system by
pulling gas from the pipeline and exhausting it
back into the compression system. With the
advent of international standards to regulate
safety and durability, these pumps offer
substantial benefits to pipeline operators.
Natural gas-powered pumps
In 2003, the Canadian Standards Association
created CSA 2.01, a standard designed to
regulate natural gas-powered diaphragm
pumps. Among other requirements, the
standard recognizes pumps that eliminate
static discharge that could potentially cause
ambient gas to ignite. The standard stipulates
that CSA-certified pumps be provided with a
grounding strap to dissipate electrical charges
and create safe working conditions.
CSA-certified pumps are tested for perform-
ance and durability as well. Achieving
certification requires that pumps endure
13,000,000 cycles without failure or leakage.
All CSA-certified pumps must complete testing
without rupture of the diaphragm or disloca-
tion of any component. In addition, pumps
must withstand leak testing at one-and-one-
half times the rated pressure. Threaded fittings
are also tested against bending and specified
torque requirements. The introduction of CSA
2.01 not only established an industry bench-
mark to measure the quality of natural gas-
operated diaphragm pumps, it helped
generate significant technological innovations
strategic for remote fluid handling at natural
gas pipeline applications.
Leak-tight technology
Exhaust discharge is one major difference
between air-operated and natural-gas
operated pumps. Standard diaphragm pumps
come with a muffler that exhausts compressed
air to the atmosphere. However, since natural
gas cannot be released back to the atmos-
phere like compressed air, gas-powered pumps
require a ported exhaust that is capable of
piping the gas away and feeding it back into
the compression system. CSA certifications
Figure 2. Compression stations are usually located every 40 to 100 miles along a pipeline and are responsible for continuing the transfer of gas. Typically operated in remote areas, these stations depend on
large motors that must be properly maintained to power the station.
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require a higher level of engineering to ensure
this gas transfer is completely leak-tight.
Thread sealant on fasteners, an often over-
looked leak threat, also helps maintain energy
integrity. Utilizing a sealant on fasteners
prevents gas bubbles from escaping the
motor during operation. Besides obvioussafety concerns, gas leaks also create effi-
ciency problems. Pumps that leak gas from
the motor yield lower flow rates and require
more energy. CSA-certified pumps deliver
safety and efficiency to pipeline operators by
guaranteeing leak-tight operation.
The CSA certification also requires manufac-
turers to produce extremely robust, high-
tolerance castings and components. To save
money, some pump manufacturers do not
require their castings to be machined, which
produces improper surface finishes and leadsto leaking at higher pressures. However, CSA-
certified pumps are tested hydrostatically for a
burst at five times the rated pressure and
monitored for component reaction.
On the major valve housing, high-tolerance,
machined bores and valving components
create round surface finishes with proper
clearances for the valve mechanism. A round
surface finish enables O-rings and U-cups to
seal as the valve is shifting, creating excellent
shift signals and leak-tight integrity at high
pressures. CSA certification also encourages
manufacturers to utilize an all-metal construc-
tion for greater durability, as non-metallic and
injection-mold housings are susceptible to UV
degradation and tend to be lower tolerance
components. On the pipeline, all-metal pumps
offer greater reliability to operators.
The CSA standards also require superior wall
thickness on pump casings, and high-strength
diaphragms. As natural gas causes the
diaphragm to expand, pressure in the pump is
created by evacuating the fluid chamber. To
withstand high-pressure force testing, diaphragm
pumps need wall thicknesses between1
/8 in and3/8 in depending on pump size.
Pump diaphragms should be built with
superior flexural strength materials like
thermoplastic elastomers (TPEs). The TPEs are
more capable of withstanding stress and
pressure created by compressed natural gas,
leading to longer diaphragm life. Similarly,
components that come into contact with the
diaphragm must be designed and connected
so as not to weaken the diaphragm. Bolted
into the connecting rod of the pump between
two large washers, the diaphragm is sand-
wiched in place. Sharp edges on these
diaphragm washers or protruding features on
the pump casing can wear a thin spot in the
diaphragm, causing tearing and rupture over
Contact
Oakley Roberts
Global Marketing Manager, Fluid Products
Ingersoll Rand Industrial Technologies
E-mail: oakley_roberts@irco.com
www.fluids.ingersollrand.com
Figure 3. A CSA-certified diaphragm pump.
time. To withstand 13,000,000 cycles and a
barrage of pressure tests, CSA-certified pumps
must be carefully engineered with smooth
surfaces.
Best practices & future technology
Pumps should always be operated at the
optimal pressure recommended by the
manufacturer. Technicians should use a filter
regulator to prevent exceeding the manufac-
turers specifications. Technicians should also
confirm that the pumps material of construc-
tion is compatible with the fluid being
pumped. In pre- and post-lube applications,
pumps utilizing santoprene diaphragms may
not be compatible with the oil being
pumped. Pipeline operators should install
pumps with hytrel diaphragms for optimal
performance where lubrication fluids are
being pumped.
Inlet pressure is another important issue. In
addition to fluid compatibility, operators
should make sure that the pressure of the
fluid coming into the pump is to specification
as well. Proper pump maintenance for natural
gas-operated pumps comes down to proper
gas pressure, matching pump materials to the
fluids being pumped and fluid temperature.
Following these guidelines will help to ensure
longer pump life.
In the future, remote monitoring technology
will continue to develop, decreasing the need
to have a maintenance technician on location
to monitor equipment. This may be accom-
plished through the integration of both wiredand wireless sensors and system components,
so that pump status can be monitored
regularly. These sensors might be employed in
leak detection through diaphragm failure
devices, cycle sensing, pressure regulation and
ensuring that the fluid stream is in the proper
condition through pressure and flow.
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