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Autonomous Shutdown Valve for Subsea PLEM Valves 1 of 11 Autonomous Shutdown Valve for Subsea PLEM Valves Brian Ennever Paladon Systems Ltd
Autonomous Shutdown Valve for Subsea PLEM Valves 1 of 11
Autonomous Shutdown Valve for Subsea
PLEM Valves
Brian Ennever
Paladon Systems Ltd
Autonomous Shutdown Valve for Subsea PLEM Valves 2 of 11
INDEX
1. Introduction .................................................................................................................................... 3
2. Typical CALM Buoy System Operation ........................................................................................ 4
3. Traditional PLEM Valve Operation ............................................................................................... 5
4. Operator Concerns.......................................................................................................................... 6
5. Autonomous Shutdown Valve (ASV) Design Features ................................................................. 7
6. ASV System Overview .................................................................................................................. 9
a. Standard System using a Spring-Return Valve Actuator ............................................................. 9
b. Optional System using a Double-Acting Valve Actuator ............................................................. 9
7. Standard ASV System Operation ................................................................................................. 10
8. Additional ASV System Resources .............................................................................................. 11
9. Contacts ........................................................................................................................................ 11
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1. Introduction
Many marine terminals in shallow water employ CALM (Catenary Anchor Leg Mooring)
Buoy and similar systems to allow tankers to moor and load and offload inventory. CALM
Buoy marine terminals have become increasing popular in shallow waters due to the signifi-
cant cost savings to be realised when compared to the construction of traditional jetties.
CALM Buoy systems comprise of the following major components:
Land based storage tanks.
Pipeline running from the land based storage tanks to a subsea Pipeline End Manifold
(PLEM) Valve.
PLEM Valve.
Submarine Flexible Hose connecting the PLEM Valve to the Buoy.
Buoy.
Floating Hose connecting the Buoy to the tanker.
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2. Typical CALM Buoy System Operation
1. The Tanker connects to the Buoy using a Mooring Hawser.
2. The Floating Hose is connected from the Buoy to the Tanker’s storage tanks.
3. The PLEM Valve is opened.
4. The Tanker’s pumps operate and either offload or load inventory to or from the land
based Storage Tanks through the Floating Hose, Submarine Hose and Pipeline.
5. Once all inventory is offloaded or loaded, the Tanker’s pumping operation terminates
and the PLEM Valve is closed.
6. The Floating Hose and Mooring Hawser are disconnected.
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3. Traditional PLEM Valve Operation
PLEM Valves have traditionally been operated in one of two ways:
Diver Operated
o A diver manually opens and closes the valve.
Valve Actuated
o A hydraulic double-acting Valve Actuator is used to open and close the valve.
The Valve Actuator’s hydraulic power supply is generated from a Hydraulic
Power Unit (HPU) located on the Buoy. The HPU and subsequently the posi-
tion of the valve actuator and PLEM Valve is controlled by personnel located
on the Buoy.
o
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4. Operator Concerns
Both traditional methods of PLEM Valve operation have significant weaknesses in relation to
operational efficiency, OPEX and environmental protection.
Diver Operated PLEM Valves
The PLEM Valve can only be operated in fair weather.
Each tanker visit requires a visit to the Buoy and diver intervention.
There are significant OPEX associated with divers; including back-up divers and dive
boats.
Slow response in the event of a Pipeline or Hose rupture, and therefore significant risk
of environmental pollution, and subsequent Operator costs and fines.
Valve Actuated
The HPU located on the Buoy is subjected to an extremely harsh operating environ-
ment, and therefore requires regular and expensive maintenance visits to ensure sys-
tem availability.
The flexible umbilical that connects the HPU to the Valve Actuator is fragile and
prone to wear and tear and subsequent failure.
The Valve Actuators used are double-acting type, and so require the application of
hydraulic pressure on both the PLEM Valve’s opening and closing strokes. In the
event that the HPU or the umbilical fails, the Valve Actuator and PLEM Valve will
remain in their current position i.e. the system will not provide a fail-safe valve posi-
tion in the event of an emergency.
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5. Autonomous Shutdown Valve (ASV) Design Features
The ASV was specifically designed to address the deficiencies inherent in the two traditional
methods of PLEM Valve operation. The main design aspects of the ASV are:
Complete subsea system
The oil filled and pressure compensated system makes the ASV immune to the effects
of surface weather conditions; and therefore allows PLEM Valve operation 24/7/360.
Self-contained
The electrical power for the system is provided via high capacity batteries that pro-
vide sufficient power for a minimum of 5 years operation; based on 3 PLEM Valve
operations per week. The hydraulic pressure for the actuator is provided from the
Pipeline itself.
Inherently fail-safe
The standard ASV system employs a spring-return Valve Actuator. The spring-return
Valve Actuator used in the ASV only requires hydraulic pressure to be applied to
open the PLEM Valve. In the event that the ASV control system fails, the spring in
the Valve Actuator will automatically move the PLEM Valve to its closed (i.e. fail
safe) position. The inherent fail-safe design of the ASV means the chance and severity
of environmental pollution in the event of a Hose or Pipeline line-break (rupture) is
dramatically reduced when compared to the traditional methods of PLEM Valve op-
eration.
Remote control operation
The ASV can be controlled remotely from either the Tanker or shore to allow PLEM
Valve opening and closing.
Automatic valve operation
With the Valve Actuator hydraulic pressure being supplied from the Pipeline itself,
the ASV can be configured to automatically open the PLEM Valve on commence-
ment of Tanker pumping operations, and automatically close the PLEM Valve once
pumping operations are terminated.
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Communication and Diagnostics
Standard communication with the ASV is via RS232 or RS485; however, wireless
and acoustic communication options are available. ASV sensors and diagnostic soft-
ware provide Operators with a comprehensive insight into the status of the system;
and allow for the implementation of cost-effective preventative maintenance pro-
grams. Standard communication and data includes:
o Remote status indication.
o Manual override function.
o In-situ diagnostics and configuration.
o Pipeline pressure.
o Valve position.
o Solenoid valve status.
o Number of completed valve operation cycles.
o Pressure sensor, solenoid valve and battery health.
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6. ASV System Overview
a. Standard System using a Spring-Return Valve Actuator
b. Optional System using a Double-Acting Valve Actuator
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7. Standard ASV System Operation
PLEM Valve Opening Operation
1. The Tanker initiates pumping operation.
2. Pressure sensors detect rise in the Pipeline, Submarine or Floating Hoses pressure.
3. Once a predetermined pressure is reached in the Pipeline, Submarine or Floating Hos-
es, the Micro Processor Controller sends an electrical signal to open a Solenoid Valve.
4. The Solenoid Valve is latched open and sends a signal to a high flow Pilot Valve.
5. The Pilot Valve opens to allow pressure from the Pipeline to pressurise a Barrier Type
Accumulator Tank.
6. The pressurised hydraulic fluid from the Barrier Type Accumulator Tank enters the
Valve Actuator’s hydraulic cylinder.
7. The Valve Actuator’s cylinder becomes pressurised, and the Valve Actuator’s spring
is compressed as the Valve Actuator moves the PLEM Valve from its closed to fully
open position.
8. The Valve Actuator continues to hold the PLEM Valve in its open position until the
Tanker terminates pumping operations.
PLEM Valve Closing Operation
1. The Tanker terminates pumping operations.
2. Pressure sensors detect a fall in the Pipeline, Submarine or Floating Hoses pressure.
3. Once a predetermined pressure is reached in the Pipeline, Submarine or Floating Hos-
es, the Micro Processor Controller sends a signal to close a Solenoid Valve.
4. The Solenoid Valve is de-latched and closes, removing a signal to a high flow Pilot
Valve which subsequently closes.
5. The Valve Actuator’s spring pushes the hydraulic fluid from the Valve Actuator’s hy-
draulic cylinder into the Barrier Type Accumulator Tank.
6. The Pipeline fluid from the Barrier Type Accumulator Tank is forced under pressure
to return to the Pipeline.
7. The Valve Actuator’s spring moves the PLEM Valve to its fully closed position.
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8. Additional ASV System Resources
Webpage
o http://www.paladonsystems.com/index.php/products/asv
Product Brochure
o http://www.paladonsystems.com/images/stories/downloads/brochures/ASVBr
ochure4.pdf
9. Contacts
Brian Ennever – Managing Director
Tel: +44 (0)1604 880700
Fax: +44 (0)1604 883263
Email: [email protected]
Mike Northwood – Product Manager
Tel: +44 (0)1604 880700
Fax: +44 (0)1604 883263
Email: [email protected]
