TPi October 2009

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40 Tube Products International October 2009
f i t t ingsfeature on . . .
LARGE compressor units, such as those
used by companies in the oil and gas
industry, are normally driven by powerful
electric engines, which are connected
to the compressor units by means of
all-metal couplings. The drawback of
this design is that harmful vibrations
induced by the piston compressor,
caused by high torsional stiffness
and weak damping characteristics of
Torsionally soft alternative to all-
metal couplings that limits vibration
the couplings, are transmitted to the
drive unit. This results in damage to
the coupling and high loads for the
bearing units, which may even cause a
breakdown of the complete system.
The Centax-SEC flexible coupling
system from Centa offers a torsionally
soft alternative to standard all-metal
couplings. The flexible couplings shift
harmful resonances to subcritical
ranges, ensuring fail-safe operation
of the compressor system. With only
minimum impact on the system, the
couplings even equalise misalignments
caused by installation and operation.
The principle of a modular design
coupling system is based on one or
more highly flexible Centax rubber
elements made of natural rubber or
silicone supplied in different ranges of
shore-hardness.
Combined with a membrane coupling,
a link or a bolt coupling, and a wide
array of flanges and hubs, the couplings
achieve flexibility in all directions, and
provide adaptability with regard to design
and construction, with a manageable
torsional stiffness. The torques cover a
range from 2.5 to 650 kNm.
Type-approved by renowned classifica-
tion societies, the couplings are designed
in consultation with the customer to
meet API standards.
Centa – Germany
The Centax-SEC flexible coupling system offers an alternative to all-metal couplings S S
JOHN Crane, a provider of engineered
products and services for the major
process industries, including oil and
gas, power, chemical, pharmaceutical,
and other general industries, has
launched a next-day delivery service
within the UK for its standard range of
mechanical cartridge seals. The new
service covers standard size seals
constructed from standard materials.
“This new service reflects the fact
that we understand our customers’
need to access the products they require
both quickly and easily,” explained John
Crane UK general manager, Colin Ure.
“Any seals covered by our new service
that are ordered before 2.30pm will be
delivered to the customer the following
working day, helping them minimise
downtime and keep their processes
operating at maximum efficiency.”
Among the seals covered by the new
service are John Crane’s 4600 Series
of single and double O-ring cartridge
seals, which are suitable for water
and wastewater, pulp and paper and
power generation applications. The
compact and easy-to-install 4610 single
seal is suitable for a variety of general
duty applications, and the 4620 dual
cartridge model meets key industry
pump standards.
Standard seals in the company’s 5600
Series Universal Cartridge Seal Family
are also available using this new service.
Suitable for chemical, petrochemical
and pharmaceutical applications, the
modular construction of the 5610
single O-ring seal and 5620 dual O-ring
seal ensures components are easily
interchangeable between different
models. This allows one seal family to
be used throughout a plant, reducing
downtime, maintenance requirements
and stockholding costs.
The new system can also be used to
access John Crane’s FFET range of
cartridge seals. Designed to reduce
installation time and errors, these
compact seals will fit all ANSI and DIN
stuffing boxes, and offer a practical
upgrade from packings.
Their robust construction makes them
suitable for applications involving
chemicals, oil, water and abrasive
liquids, especially those involving top-
entry mixers where the liquid product
may not provide continuous cooling and
lubrication of the seal faces.
John Crane – UK
Rapid delivery of seals
John Crane mechanical cartridge seals S S
are now available with a next-day delivery
service within the UK