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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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Feature2

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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Feature 3

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: [email protected]

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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