non-intrusive acoustic valve inspection (navi) theory & applications mohammad nazri mudin...

Non-Intrusive Acoustic Valve

Inspection(NAVI)

Theory & Applications

Mohammad Nazri MudinAmserve Engineering Sdn. Bhd.

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VALVE PASSING

Amserve Engineering Sdn. Bhd.

FACTORS IMPACT

• Seat alignment

• Insufficient actuator travel

• Poor maintenance

• Corrosive and/or erosive process media

• Valve seat is prevented from fully closed due to dirt/rust.

Safety

Environment

Production

Asset Integrity

Refers to flow through a valve which is set in the “off” state (closed).

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NON-INTRUSIVE ACOUSTIC VALVE INSPECTION (NAVI)


• Technology from France

• Used widely in Nuclear Power Plant to detect passing valves and steam traps

• Experience more than 20 years

• Europe, North America, Africa

• No permanent installation required

• Inspection is fast and reliable

• Estimation of leak rate based on actual data collected

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WORKING PRINCIPLES


• Based on passive measurement of ultrasonic acoustic emission. These sounds are generated by the flow of fluids through leaking valves under pressure.

• The NAVI hardware takes the sound measurement signals, processes and displays them as a signature most suitable to identify and quantify the leaks.

• Test requirements• Valve to be tested must be in closed position• There is a differential pressure across the valve, at least 1 barg.

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THEORY OF APPLICATION


• Acoustic emission is a structure borne noise and it is generated by the process medium flow. NAVI detects leak noise caused by turbulent flow, which is measured in decibels (dB).

If a valve is in open position, there will be laminar flow that generates little or no noise.

A tight valve makes a very little or no noise.

A passing valve creates turbulent flow and acoustic noise. The AE is transmitted into the valve body.

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INSPECTION TOOL


Sensor Cable/Sensor

Heat Sink Compound

Hardware• Panasonic

Toughbook Model CF-19/Getac

• Touch-sensitive screen

• Acquisition card up to 2400 kHz

• Intrinsically safe (Zone II)

Software & Accessories• Digital NAVI Analyzer• Contains database,

current and previous.

• Piezoelectric accelerometer and heat sink compound

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AE MEASUREMENT


2. Place sensor on the upstream piping, take background noise.

1. Place sensor on the valve body, take pressure noise.

3. Place sensor on the downstream piping, take background noise.

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DATA ACQUISTION


Pressure Noise (Body)Background Noise (Up) Background Noise (Dwn)

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ANALYSIS


Differential Signature

Background Noise (Up) Background Noise (Dwn)Pressure Noise (Body)

Analysis• If Pressure Noise is greater than Background Noise, then the valve leaks.• If Pressure Noise is equal to Background Noise, then the valve is tight.

VALVE PASSING

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ANALYSIS


Differential Signature

Background Noise (Up) Background Noise (Dwn)Pressure Noise (Body)

Analysis• If Pressure Noise is greater than Background Noise, then the valve leaks.• If Pressure Noise is equal to Background Noise, then the valve is tight.

VALVE TIGHT

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ANALYSIS


PASSING NO PASSING

Continue Monitoring 6-MonthlySmall Medium Large

Small Leak – 1 to 9 dBContinue Monitoring 6-MonthlyMedium Leak – 10 to 23 dBValve Need Repairing

Large Leak – 24 dB and aboveValve recommended to be replaced

Tolerable Leak Threshold for Various Type of Valves (Shell IMP 3.02 Table 1)

Estimation of Leak Rate

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CASE STUDY 1: LAUNCHER PRESSURE BUILT UP RECTIFICATION (EXTRACT FROM CLIENT REPORT)


JANUARY 2013

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CASE STUDY 1: LAUNCHER PRESSURE BUILT UP RECTIFICATION

Trunkline RY (Launcher L-2900) and Trunkline RZ (Launcher L-2910) found high pressure build-up in launcher barrel (up to 80 barg/day) after pigging activities.

After lubrication & sealing, RY launcher pressure build up controlled at 1 – 2 barg/day. RZ launcher pressure build up higher at 3 – 5 barg/day.

Further rectifications was requested to verify root cause.

Action Items:• Mobilized Amserve to conduct non-intrusive acoustic valve inspection on MOVs to

determine leakage rate; and check for any passing from kicker line and vent line.• Mob valve maintenance vendor to conduct MOVs alignment, perform greasing and

sealing.• Amserve to verify passing valves and final leakage rates.


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Non-Intrusive Acoustic Valve Leak Inspection was performed on• MOV290X1, MOV290X2• Kicker Valves (VX-2901, VX-2902)• Equalizing Line Valves (VX-2904, VX2905)• Vent Valves (VX-6395, VX6396)

MOV290X2 MOV290X1


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NAVI Result for RY (L-2900)• No serious passing detected from kicker valves, equalizing line valves and vent valves.

Pressure build up not likely contributed from these valves.• MOV290X2 (riser side/tee) passing rate still within allowable limit, but the high dB

ratio indicate ACTUAL passing rate could be higher than the estimation.• MOV290X1 (launcher side) passing rate exceeded allowable limit, but lower than

MOV290X2.

CONCLUSION: Build up of pressure in launcher is likely from MOV290X1 and MOV290X2.


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TOLERABLE LEAK THRESHOLD (SHELL IMP 3.02 TABLE 1)

Item Types of ValvesTolerable Leak Threshold Warning Limit

(% TLT)

Gas service (kg/s) Oil service (kg/s)

1 Riser ESD Valves (1) 0.1 0.1 752 Launcher/Receiver 1st MOV (at barrel) (1) 0.01 0.01 503 Launcher/Receiver 2nd MOV (at barrel) (1) 0.1 0.1 754 Process ESD Valves (SDV, ROV) (2) 0.1-0.3 0.1-0.3 755 Depressurization or Blow-down valves (3) 0.03 0.03 756 Motorized Isolation Valves (MOV) (4) 0.01, 0.1 0.01, 0.1 50, 757 Process Control Valves and FCV (5) 0.1-0.3 0.1-0.3 758 Mechanical Isolation Valves (6) 0.01, 0.1 0.01, 0.1 50, 759 Integral DBB Valves (7) 0.01 0.01 75

10 Non Return or Check Valves (8) 0.3 0.3 75Note:•Based on consequence of 2 mm pinhole leak with 5 m jet fire as per Riser Tolerable Leak Rate Study Rev.0 Mar 2008.•Rate of 0.1 kg/s is based on the worst case consequence similar to Riser ESD valves with blow-down duration of 15 min or more and 0.3 kg/s for case with depressurization less than 10 min from maximum operating pressure to 7 barg.•Rate is based on flaring limit of 0.1 MMscfd of one valve or 2.0 MMscfd for total valves of the platform.•Rate is based on consequence cases similar to Pig-trap valve, i.e. last barrier 0.01 kg/s and otherwise 0.1 kg/s.•Only for FCV and those process control valves that serve also as shutdown valves (no other Process ESD valves) and rate shall follow the Process ESD valves.•Rate is based on consequence cases similar to Motorized isolation valves.•Rate is based on consequence case similar to last barrier of MOV, i.e. 0.01 kg/s•Rate is based on the consequence of blow-down valves.

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Result after cleaning and re-sealing

• Pressure built up contained to 0 barg after 2 days of monitoring (2 barg after 4 days).

• NAVI was conducted again, result shows MOV290X2 is still passing and confirmed by continuous passing of gas at body vent.

• MOV290X1 shows minimal passing, and greatly reduced passing from body vent. Most of riser pressure is being contained by MOV290X1.

• MOV290X2 shall be replaced as soon as possible.

• MOV290X1 shall also be considered for replacement. Without sealant, leakage will become worst.


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CASE STUDY 3: TO IDENTIFY PASSING CHECK VALVES FOR P-6250


JAN 2013

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CASE STUDY 2: CHECK VALVES


System Area: M1 P-6250Situation: Pump suction check valves and pump discharge check valves were suspected passing, however could not be identified.

Action Items:Amserve to carry out NAVI. Pump was let run until reach consistent desired discharge pressure, then stopped to create backflow.

Result:Passing valves were identified. Leak severity ranged from small to medium leak, however estimated leakage rates are still within tolerable leak threshold for check valves (0.3 kg/s).

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CASE STUDY 3: VALVE PASSING VERIFICATION FOR A NEWLY INSTALLED VALVE AT TML PLATFORM


MAY 2012

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CASE STUDY 3: TML NEWLY INSTALLED VALVE


System Area: TML’s BR-A Pipeline Isolation ValveSituation: During recent shutdown, a new valve was installed to replace previously reported passing valve. During pressurization, pressure build-up was observed at the downstream. Client requested for verification and estimation of leak rate, as not to exceed the standard allowable leak rate* (1 kg/min for natural gas).

Action Items:Amserve was notified on the situation and was mobilized to site.

Result:It is found that the valve passing and the estimated leak rate is still within the allowable leak rate. OIM and maintenance team were notified on our findings.

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BENEFITS


Identify passing valves.

• Avoid unnecessary valve repair• Identify repeat leaking valves• Identify leaking valves to increase efficiency

Safety

• During maintenance, ensure effective isolation.

Environment

• Reduced flaring/emission

non-intrusive acoustic valve inspection (navi) theory & applications mohammad nazri mudin...

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