which is a more difficult medium to isolate compared to air.
This low pressure test reduces the seating load forces and, as a
result, makes it more difficult to provide zero-leakage
performance in comparison to the requirements of FCI 70-2.
The dynamic phases of the process subject the valve to
significant temperature cycles, where the valves are exposed to a
normal temperature of 40°C during the absorption phase and
increase to 350°C during the regeneration phase. Valve design and
systems using a variety of metal materials will need to adapt well
to these changing conditions. The heavy duty Belleville spring
holding the ball against the seat along with live-loaded stem
packing in the ValvTechnologies’ product allow the components of
the valve to expand and contract through thermal cycles. This
ensures the sealing materials and components remain loaded and
that the valve allows no internal or external leakage.
The differential pressure across the valve in the closed position
can be a challenge for valve designs requiring pressure to increase
sealing forces. When the valve is closed, many of these
dehydration systems have a 7 – 14 psig (0.5 – 1 barg) pressure
differential, which minimises the loading forces created by
pressure. A valve design that does not rely on pressure for seating
forces is an ideal choice for this application.
Make the right choice
The first V Series valve was installed in July 2003 for regeneration
switching isolation and was in service until August 2011, which
increased the operating life from 18 to 97 months. Initially, the
acquisition price of the valve was two times more than rising stem
ball valve in service. However, after just over 8 years in service, the
cost of ownership was significantly lower, and the downtime for
the plant was considerably less. The original rising stem ball valve
purchase price was US$9000 and cost, on average, US$5000 to
repair every 18 months. The cost of ownership for these valves
over an 8 year period would have been US$34 000 compared to
the purchase price of US$19 000 for ValvTechnologies’ valve. In
addition to this, once all of the switching valves were changed,
downtime caused by valve failures or leakage was significantly
reduced. The production foreman estimated that the new valves
realised a US$3 million benefit to the facility through zero-leakage,
increased uptime and reduced maintenance. The product has
addressed the challenges presented in this application and helped
to increase the operating duration of the process.
In demanding and challenging severe service applications,
good review techniques and communication are instrumental in
finding the right product for the application to enhance process
systems.
Figure 4.
RiTech
®
coating application.
NORTH AMERICAN
PRODUCED
October 11-13, 2016
Chicago, Illinois
McCormick Place
