Shell VPAC User Training Course 40609
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Transcript of Shell VPAC User Training Course 40609
. 1 Physical Acoustics Limited © 2009
Physical Acoustics Ltd VPAC - Quantification of Through Valve Gas &
Liquid Losses
. 2 Physical Acoustics Limited © 2009
VPAC – Valve leak detection system and technology package. 5131 – is the hardware component made by Physical Acoustics.
Physical Acoustics developed VPAC with BP and Shell (since 1982). PAL manufacture the hardware and sell package under licence.
Identification of leaking/passing valves is important for safety and to minimise losses.
Physical Acoustics Ltd, based in Cambridge, provides - VPAC systems- Operator training (on and offshore)- Valve testing services with trained VPAC engineers- System maintenance, repairs and spare parts - Consultancy and advice on use and testing strategy
Overview
. 3 Physical Acoustics Limited © 2009
Principles Of AE Leak Detection
Acoustic Emission (AE) is Structure Borne Noise.
AE May Be Generated By:
- Propagating Cracks
- Spalling Corrosion Product
- Turbulent Flow
VPAC detects leak “hiss” caused by turbulent flow, which is measured in dB (AE)
. 4 Physical Acoustics Limited © 2009
Open Valve(laminar flow)
If a valve is open there will be laminar flow that generates little or no noise.
Acoustic Emission Generation
Sensor & VPAC
. 5 Physical Acoustics Limited © 2009
Tight Valve(little noise)
A tight valve makes very little noise.
Acoustic Emission Generation
Sensor & VPAC
. 6 Physical Acoustics Limited © 2009
Turbulent Flow(significant noise)
A passing valve creates turbulent flow and hence acoustic noise. The AE is transmitted into the valve body and can be detected with the 5131.
Acoustic Emission Generation Sensor & VPAC
. 7 Physical Acoustics Limited © 2009
VPAC / 5131 DEVELOPMENT
. 8 Physical Acoustics Limited © 2009
B.P. and Shell Development Program
1982 - BP evaluation of technologies for valve leak detection/quantification.
1984 - BP concentrated on AE technology for laboratory testing and field trials.
1984 -1990 BP extensive field trials and database development.
1991 - BP/PAL specification of new instrument. 1994 - BP license technology to PAL. 1997 - BP & Shell develop liquid & gas ESD/large diameter
valve correlations. Physical Acoustics sells and supports VPAC worldwide.
. 9 Physical Acoustics Limited © 2009
Database Development Identify leaking valves using AE monitor
Remove leaking valves from service
Re-test valves in lab. using flow-meter and acoustic monitor to develop database
1984-1990 800 valves, up to 18”, plug, gate, ball, globe, PSV, PCV, and others
Develop graphical and numeric correlation from the database
. 10 Physical Acoustics Limited © 2009
. 11 Physical Acoustics Limited © 2009
VPAC - Field Experience
5-10% of valves suffer through-valve leakage.
1-2% of these passing valves are responsible for 75% of total losses.
Leaks can exceed 1000 litres/minute
Leaks down to <1 litre/min detectable
. 12 Physical Acoustics Limited © 2009
VPAC - Field Uses
Maintenance planning – identify leaking valves prior to shut down.
(Safety Issues).
Reduces losses to atmosphere through vent pipes.(Environmental Issues).
Reduce loss to flare (even if there is a gas recovery system savings can be made). (Reducing Costs).
. 13 Physical Acoustics Limited © 2009
VPAC - Field Uses
Trouble shooting – tracing leaks and sources of cross contamination.
Re-qualifying PSV’s after operation.
ESD’s testing (save 6-12 hrs production).
. 14 Physical Acoustics Limited © 2009
Some VPAC Customers Shell Exploration and Production UK, OneGas, Shell
Sweden, Shell Denmark, Shell U.K. Oil Sapref, Natref, StatoilHydro, HPCL BP, SRC, Nerefco, Petrofac Gulf Oil, Total, NAM, OK, Noretyl, Neste Oil Lindsey Oil, Natref, ConocoPhillips, Indian Oil Phillips Petroleum, Irish refining, BPCL British Gas, BSP, Saudi Aramco (Multiple Sites) TAKREER, PDO, ChevronTexaco, Occidental, Ras
Gas, Shell Brunei, Oman LNG ………………
. 15 Physical Acoustics Limited © 2009
“1993 VOC losses AU$9m [~US$12m], cut to half (14,342 tonnes) by end 1995, by end 1996 cut to 4821 tonnes.”
(28,684 tons per annum to 4821 tons per annum)
. 16 Physical Acoustics Limited © 2009
PAL have recently supplied Shell and One Gas with 18 VPAC systems as part of the UpGrade Project
PAL have trained on the Shell Anasuria, Brent B and C, Dunlin, Eider, Gannet, Nelson, North Cormorant, Shearwater and Tern platforms.
PAL also have trained and provide VPAC testing services at Shell St Fergus.
PAL have also trained on the OneGas East AWG-1C, F3-FB-1, K8-FA-1, K15-FA-1, K15-FB-1, L2-FA-1, L5-FA-1, L9-FF-1 and L13-FC-1 platforms
PAL are about to start VPAC training campaign in the southern UK north sea for OneGas West
In total PAL have trained about 400 offshore personnel in VPAC testing
Overview of Shell VPAC Project
. 17 Physical Acoustics Limited © 2009
VPAC SYSTEM
. 18 Physical Acoustics Limited © 2009
VPAC – 5131 System
Portable unit (2kg)
I.S. Sealed unit Battery charger 2 x HF sensor Case Wave guide User manuals Leak rate
calculation excel
. 19 Physical Acoustics Limited © 2009
Using VPAC To turn on, press Enter. Wait until Auto Ranging completed. Make measurements.
Record dB value in excel work sheet against valve I.D. along with differential pressure.
Hold down M button for a few seconds to power down (or system has auto switch off in 2mins).
Enter record into excel SW table for permanent records.
Stored Memory Point (1-300)
1 13 50
Stored Value At Memory Point
Current Measured Value
. 20 Physical Acoustics Limited © 2009
Testing Process Ensure the valve is closed.
Valve must be subject to differential pressure 0.5 bar gases, 3 bar liquids (these are minimum pressures as flow must be turbulent).
Clean away loose rust and scale.
Hold sensor on valve body using grease as acoustic couplant.
Let measurement stabilise - take reading.
Take upstream and downstream readings to check valve is source.
. 21 Physical Acoustics Limited © 2009
Measurement Positions Valves <24”
Note it is good practise to make several measurement per valve
. 22 Physical Acoustics Limited © 2009
Measurement Positions Valves over 24”
• Make a measurement approximately every 300mm across the body of the valve and flanges
• Use the highest VPAC reading the loss control equation
. 23 Physical Acoustics Limited © 2009
Plant Noise• <10% of plant valves may have noise from other site processes and you will experience it.
• VPAC measurements upstream and down stream ensure that VPAC reading at valve is leak and not false.
• Valve reading must be 6dB+ than upstream/down stream reading to be used in the leak rate equation.
• No compensation is required in the spread sheet - use peak VPAC reading from valve
. 24 Physical Acoustics Limited © 2009
Noise Measurement Positions
Ideally noise check measurements are 0.5 -1m from valve
0.5 -1m 0.5 -1m
Noise check point
ONLY USE VALVE MEASUREMENT IN LEAK CALCULATION
. 25 Physical Acoustics Limited © 2009
Plant Noise – Example Results
Up stream Valve Down stream Result13dB 13dB 13dB No leak19dB 52dB 19dB Leak62dB 72dB 23dB Leak71dB 52dB 52dB Noise
Remember – there is no need to compensate for up/down stream readings if measurement at valve is 6dB bigger.
. 26 Physical Acoustics Limited © 2009
5131 Menu Functions
For normal operation use as delivered.
There are option changes that can be made – But these have no benefit to testing.
No Need to Change Settings!
. 27 Physical Acoustics Limited © 2009
VPAC LOSS CALCULATION SPREADSHEETS
. 28 Physical Acoustics Limited © 2009
Spreadsheet Calculation of Losses
4 leak rate equations
- Gases <18 Inch
- Liquid <18 Inch
- Gas ESD, large valves 18< and soft seat valves
- Liquid ESD, large valves 18< and soft seat valves
. 29 Physical Acoustics Limited © 2009
Using Estimation Software
Simple Excel format. Calculations built In. Make sure correct spreadsheet is used GAS,
LIQUID, ESD. During Measurement Note:
- Valve ID -5131 Reading
- Inlet Valve Size -Valve Type
- Differential Pressure - Product
. 30 Physical Acoustics Limited © 2009
There are four pages in the Shell platform specific Excel spreadsheet – make sure you use the correct one.
VPAC Gas – Gas up to 10” diameter
VPAC Liquid – Liquid up to 10” diameter VPAC Gas – Gas over 10” diameter VPAC Liquid – Liquid over 10” diameter
Which Spreadsheet?
. 31 Physical Acoustics Limited © 2009
Other Considerations
Safety Intrinsic Safety Operating temperatures and use of wave guides Trouble shooting Lagging / Insulation Online monitoring
. 32 Physical Acoustics Limited © 2009
Safety Consider if you need to raise a permit to carry out VPAC testing.
Always carry VPAC system in the case with sensors pre-connected and stored in the front pouch. This will protect the system and stop it catching on plant and scaffold etc.
Climb ladders with 2 hands with the case over your shoulder.
If using the wave guide fit it in a leather sheath – if not needed leave it behind.
Never put the wave guide in your pocket as it could spear your leg or fall out.
Wash our hands and wipe down sensors/cable to remove grease.
. 33 Physical Acoustics Limited © 2009
Intrinsic Safety The unit is IS certified as long as its not tampered
with.
This unit Cannot be user serviced.
If unit malfunctions contact PAL. Do not open the casing, this will invalidate the IS certification.
Remember to connect and disconnect the sensor only in a safe, gas free environment
. 34 Physical Acoustics Limited © 2009
Surface Temperatures
Probe will operate at temperatures up to 1250C (not continuous contact).
Above this temperature use a waveguide.
But there will be a loss of signal through waveguide – small leaks will not be detectable.
. 35 Physical Acoustics Limited © 2009
Waveguide Correction
When you find a leaking valve – note reading.
Retest using waveguide – note reading.
Make a note of difference, this gives correction for waveguide.
However, the readings will be unreliable and cannot be used to estimate leak rates, they can only be used as a guide.
. 36 Physical Acoustics Limited © 2009
Lagging & Insulation Hot valves may well have lagging or jackets on
them.
Customer must consider any preparation of lagged valves in advance of test
Never modify or cut off lagging without permission - it may have trace element heating underneath
Jackets must be put back on post test and sealed properly
. 37 Physical Acoustics Limited © 2009
Troubleshooting
If the 5131 is used correctly faults are not common.
Most common is probe damage due to impact damage or at connector due to heavy handed connection / disconnection.
If damaged probe reads (in air) 16+dB or 6-11dB replace probe and retest with sensor clasped in your hand (this shields it from electric noise).
If problem is not resolved call PAL who can advise.
. 38 Physical Acoustics Limited © 2009
VPAC Permanent Leak Sensor System
There are many situations when intermittent surveys are undesirable and ‘Real Time ‘ leak monitoring is required.
To achieve this we supply a sensor and amplifier unit which has an industry standard 4-20 mA output.
This provides an intrinsically safe solution for leak detection in hazardous environments. 1276 zener Barrier – 1278 galvanic barrier.
. 39 Physical Acoustics Limited © 2009
4-20 MA output to DCS or turnkey system
VPAC ONLINE IS Sub System
. 40 Physical Acoustics Limited © 2009
What next - Hands On!
. 41 Physical Acoustics Limited © 2009
Thank you for your attention.
Do you have any questions?
VPAC Training Course