Shell VPAC User Training Course 40609

. 1 Physical Acoustics Limited © 2009

Physical Acoustics Ltd VPAC - Quantification of Through Valve Gas &

Liquid Losses


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


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)


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


Tight Valve(little noise)

A tight valve makes very little noise.

Acoustic Emission Generation

Sensor & VPAC


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


VPAC / 5131 DEVELOPMENT


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.


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



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


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).


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).


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 ………………


“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)


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


VPAC SYSTEM


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


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


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.


Measurement Positions Valves <24”

Note it is good practise to make several measurement per valve


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


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


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


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.


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!


VPAC LOSS CALCULATION SPREADSHEETS


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


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


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?


Other Considerations

Safety Intrinsic Safety Operating temperatures and use of wave guides Trouble shooting Lagging / Insulation Online monitoring


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.


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


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.


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.


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


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.


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.


4-20 MA output to DCS or turnkey system

VPAC ONLINE IS Sub System


What next - Hands On!


Thank you for your attention.

Do you have any questions?

VPAC Training Course

Shell VPAC User Training Course 40609

Documents

vpac quantification

valve body

valve leakage

valve testing services

vpac field experience

acoustic noise

ae technology

leaking valves