31,32,35

8/3/2019 31,32,35

1/3

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.

www.valve-world.net July/August 2011 31

O i l & Gas / OffshOre

8/3/2019 31,32,35

2/3

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

www.valve-world.net32 July/August 2011


8/3/2019 31,32,35

3/3

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.

www.valve-world.net July/August 2011 35


Documents

31,32,35