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Fasani slab gate valve which includes an
integrated linear actuator
Tyco Valves & Controls FCT hyperbar ic
chamber for simulated testing in ultra deep
water projects
Keywords:Actuation Design Subsea valves
Proven performance is key for
valve and actuator components
used in subsea applications. As
subsea well and pipeline equipment
keeps pace with industry developments
which enable seabed processing and
extraction operations, so too must valveand actuator manufacturers continue
to innovate and provide highly reliable,
maintenance-free solutions. This approach
requires high level engineered products
that offer proven performance through
an extensive test program including
hyperbaric testing to simulate the severe
conditions present at ultra deep water
depths of 3000 metres.
Ultra-deep water applications require the
most robust and reliable equipment. For
subsea projects in shallow coastal waters,asset operators can use experienced dive
teams to reach damaged or faulty valve
and actuator components. Maintenance
operations in deeper waters, however,
are far from ideal and the immense
depths involved in ultra deep water
projects in particular signicantly restrict
the repair of valves and actuators. Whilst
this equipment can be retrieved by
ROV, it is not the preferred solution. In
these applications, valves and actuators
are designed and test to operate
automatically throughout their expected
lifecycle, which can be between 20 and
50 years, without repair.
Design standards, but notstandard designsThe main standards involved in the
design of subsea valves are ISO 13628
4 / API 17D: Subsea wellhead and
tree equipment, and ISO 14723 /
API 6D SS: Subsea Pipeline Valves. As
product reliability becomes ever more
important, API 17D has become the
reference standard. These standards
introduced life cycle endurance testing
intended to evaluate the long term
wear characteristics of the equipment,
and hyperbaric testing to demonstrate
the performance limits of the valve
and actuator assembly. However, both
operators and manufacturers understand
that the limited accessibility of installed
equipment and the uniquely harsh
environment of the deep ocean require
design and materials to outperform any
scenario that can be conceived.
Factors affecting design andperformanceValve and actuator designs have had to
evolve to cope with the challenges of
operating in ultra deep water, and the
subsequent hydrostatic pressure caused
by the total height of the seawater
column. Hydrostatic pressure produced
by the weight of the seawater submits
submerged equipment to pressure
equal in all directions which impacts
on the valve operating torques and
self-seal capabilities. Where the internalpressure of the valve is atmospheric , for
example, then the valve shell and sealing
components may face high differential
pressure. To overcome challenges of
By Pieter Kok, Tyco Valves & Controls
Advances in Automated
Subsea Valves
Signicant steps in the
global subsea oil and gas
industry have pioneered new
engineering techniques in both
exploration and extraction. As
the industry has moved into
ultra deep water applications,
this has presented a range
of technical challenges with
regards to the design and
performance criteria for
critical equipment, such as
valve and actuation systems.
Here, Pieter Kok reviews these
technical challenges and the
key considerations during the
design process and testing
procedure in order to provide
a fully veried solution for
specic applications.
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operating in such extreme environments,
a number of considerations need to
be made in the overall design and
construction of valve and actuation
equipment and given the performance
requirements of ultra deep water
applications, a long design life based onhigh efciency is key.
Signicant temperature changes pose a
risk for valve and pipeline integr ity. With
deep seawater generally no more than
2C, this can be at great contrast to the
temperature ow within the pipeline
liquids upstream of the eld can be 80C
and above for high temperature wells.
Despite dramatic advances in subsea
engineering capabilities, the pressures
and temperatures in ultra deep water
operation create an environment thatis highly conducive to leakage due to
the immense depth and excessive
temperatures involved. For actuators
specically, ensuring that no piping and
ttings are connected to pressurised
sections will dramatically reduce the risk
of leakage.
Addressing design
considerations up frontEnd user or OEM specificationscan differ by region which creates a
challenge when designing valve and
actuation equipment to meet with
these necessary approvals. Complying
with such standards requires a number
of considerations to be made in the
design process. Since requirements and
specifications are changed in relation
to the water depth and operational
environment, a new approach to design
and development is needed to delivera valve and actuation package which
meets the specific project requirements.
Depths of more than 1,000 metres
offer many challenges to engineers.
Water pressures, corrosion,
temperature fluctuation and variances
in the viscosity of the liquid flowing
through the pipeline must all be
considered as part of the overall valve
and actuation system design. Specific
criteria relating to special material
selection, optimised torque profile
and online diagnostic capability can
all contribute to more effective and
efficient design for ultra deep water
valve equipment.
Hydraulic actuator design in ultra deep
water
Considerations for fail safe hydraulic
actuator design have the same
requirements across both shallow
and ultra deep water applications. For
instance, the materials typically selected
are protected with specific painting
systems to prevent seawater corrosion.
Furthermore, both mechanism housing
and spring cartridge are pressure
compensated by a closed or open
circuit, to allow the use of the reduced
structure not becoming overstressed
by the external pressure at depths
of 3,000 metres. The most significant
change however to fail-safe actuatorsfor ultra deep water is in the design
philosophy of the ROV override
mechanism.
Overriding the ROV system enables direct
operation using low resisting torque which
avoids compression of the spring. During
the ROV stroke, the actuator spring is
not compressed preventing this critical
component being overstressed, and
reducing the risk of mechanical fatigue.
This design includes a functionality in the
valve actuator coupling system allowingto perform the actuator/valve diagnosis
by uncoupling the spring actuated clutch
via an ROV operated tool from the valve
stem adaptor without removing the
actuator. Therefore the actuator can be
stroked without moving the valve, thus
allowing functional check of the actuator
itself. After the diagnostic test actuator
will automatically return to the normal
position when the rst operation is
carried out.
Maintaining a commitment totestingIn todays business environment it is
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Functional testing for subsea valves using a hyperbaric chamber
essential that continuous investments
are made, particularly in research,
development and product testing.
There can be no compromises when it
comes to testing for ultra-deep water
operation. Although many of the design
requirements for valves and actuatorsoperating in the rigorous subsea
environment are common, there are
specic needs for assemblies working in
the deepest locations.
Testing and quality control minimises
the risk of failure or fault and products
undergo a stringent course of test
procedures including hydrostatic shell
testing, vacuum tests, stepwise seat
tests, seat relief test, jam test, hyperbaric
chamber testing and sand slurry tests.
Extended lifecycle testing furtherexposes the components to temperature
extremes, whilst at the same time
dynamically cycling the products under
various pressure conditions to check
seal integrity and component mechanics.
Though design standards require 200
dynamic cycles for an automated hydraulic
valve, some oil and gas operators and
subsea product suppliers have introduced
a stringent requirement based on sixtimes the number of operating cycles to
ensure there are no concerns regarding
the robustness or performance of a valve
and actuation system.
The Tyco approach to thesubsea industryThrough its FCT ball valve, Fasani slab
gate valve and Bif actuator brands, Tyco
continues to invest in its engineering
resources in subsea. Because there is no
such thing as a standard well or valve every control package is custom-built. This
approach ensures that at the specication
stage, the design team adapt proven
designs to suit the pressure, temperature,
and medium passing through the valve
its corrosiveness and state . Actuators
are selected for the appropriate working
conditions. From approved designs,
forged valve components are received
in the workshop, where the in-house
team undertake manufacture, weldingand assembly of the valve and actuation
system. This is then tested individually and
as a complete package.
As a global valve and control expert
designing valves and actuators for
the subsea oil and gas industry, rather
than a subsea company manufacturing
valves, Tyco can apply insight and
industry knowledge to comply with the
requirements for any specic application
or project.
The pace of development and changewithin the subsea oil and gas extraction
industry continues to present many
challenges and opportunities. Valve and
actuation product manufacturers have
a responsibility to ensure the maximum
safety for people and the environment.
Only by working collaboratively with a
strong focus on testing and measurement
can the industry succeed in recovering oil
and gas from ultra-deep water it really is
a case of no compromises.
About the authorPieter Kok is Global
Market Manager
Upstream, Oil & Gas
at Tyco Flow Control.
After studying as a
mechanical engineer
he joined Anderson Greenwood
in 1983 as a product specialist
for safety relief valve and
instrumentation products. AndersonGreenwood became part of
Keystone in 1987 and he continued
his role as product manager.
Since Keystone joined Tyco Flow
Control in 1989 he has held several
positions in international sales
and marketing for the Anderson
Greenwood brand. Prior to his
current role, he held several
positions as sales and product
manager for Tyco Engineered
Products responsible for thedifferent Tyco Valves & Controls
products in international markets.
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