controlling noise on offshore installation during design...

Lloyd’s Register Energy Conference Safety-driven performance 2012

Controlling noise on offshore installation

during design and commissioning

West Elara case

Philippe Loustau

engineering manager

October 18, 2012


Offshore noise control

• What are the challenges for offshore noise control?

• Compact environment: proximity of noise sources

• Compact environment: little space availability for noise control measure

• Use of high power equipment: high strength of noise sources

• Rig weight must be kept under control

• Drilling assets specificities

• Moving around the world and need to comply with local regulations


Noise Damage

Factors which increase the risk of hearing damages

• Duration

• Volume

• High frequencies more than low

• Pure tones more than broadband noise

• Strong sound impulses

• Individual sensitivity (glass hear)

Secondary adverse effect

• Stress

• Tinnitus• High blood pressure

• Changed breathed rhythm• Reduced power of concentration


Typical NORSOK S-002 scheme

• NORSOK S-002 regulation suggests a framework for performing noise study

• Step 1: Establish noise specification for equipment through noise maps

calculations, using baseline sound level from experience

• Step 2: Update noise maps with OEMs data (working with the noise source)

• Step 3: Implement noise control measures if needed (working with the

noise transfer path)

• Step 4: Implement signaling for hearing protection if an area cannot reach

the noise level target (working at the receiver)

• Noise is not only propagating airborne, structure borne propagation is not to

be neglected.


West Elara assessment – facility presentation

: 1.5 mm steel plate

: 1.5+3 mm steel plate

: 2+3 mm steel plate + viscoelastic glue


West Elara assessment – requirements

Area noise level

• Per Norsok S-002

• From 45 dB(A) for medical room to 110 dB(A) for unmanned machinery room or emergency generator room

Sound insulation

• From 35 to 45 dB between cabins in the living quarter

Other acoustic requirements

• Corridors, not more than 5 dB more than the quiet room noise level (working

area)

• Access to walkways to permanently manned areas should be provided without

passing through a zone with a noise level above 83 dB(A)

Vibration Exposure

• Table from Norsok for human body vibration (acceleration levels depending on

frequency)


West Elara assessment – living quarters

• Area noise level

• Laundry room (rigid mounting)

• Piping vibration (rigid mounting)

• Equipment vibration (rigid mounting)

• Sound Insulation between cabins

• From 31dB to 38dB. Below required 40 dB.

• Vibration exposure

• Equipment vibration (rigid mounting)

0 10 20 30 40 50 60 70 80 90

partition panel (towards desk)

Partition panel (towards corridor)

HVAC (supply)

HVAC (extract)

Ceiling

Window

Lining panel

Floor

Door

Lp [dBA, ref. 20 microPa]


West Elara assessment – utility area

• Mechanical workshop

• Next to the engine room and separation by a single steel bulkhead covered with fire protection and a single door

• Influence from pump room identified during testing

• Platform deck

• Mud lab: likely excess of area noise due to poor sound isolation properties of door

• Main Deck

• High noise level from extraction fan 85 dB(A)

• HVAC contribution

• Significant excess from +6dB in rubber good store to +26dB in electrical workshop

• PA-system intelligibility

• Recommended RASTI of 0.7 in recreation areas and 0.35 in work areas with up to 85 dB(A) noise level


Step by step procedure for troubleshooting

1. Noise survey including determination of sound power

2. Analyze the survey

3. Suggest noise reducing remedies including the likelihood

of the cause

4. Client choose noise insulation

5. Verification by measuring

6. Evaluation of changes


Offshore noise control• Noise control measure for offshore installation

• Acoustic control• Sound insulation• Noise from pipes and valves• Noise attenuating enclosure• Silencers• Vibration isolation

• Other conditions to take into consideration

• Resistance to water / oil• Maintenance (washing / cleaning)• Impact strength• Fire• Paint• Corrosion condition (CUI …)


Partition panels covered with steel plate in test cabinActual panel not performing according to specMock up cabin built for testing

Examples of recommendations – living quarters


Air exhaust - silencers

Air exhaust and inlet on main deck injection fans - exhaust line

Example of recommendations – Utility area

Additional silencers


Forklift corridor

Left: May 2011, Pump Room #2 with forklift corridor before installation of wall.

Right: July 2011, Screening wall installed between equipment and walkway/fork lift area.


Chiller foundations

Chiller foundations – E deckOn top of some cabins


Hvac extracts - silencer

HVAC extract on top of driller’s cabin – used to avoid the noise from drill floor to the cabins

Silencer

Example of recommendations – Utility area


Mechanical workshop – buffer zone

Left: before installation of buffer zone (between engine room) Right: buffer zone installed with an other door


Conclusion

• As regulators are moving towards more and more stringent regulations in

the area of noise, it is important to consider noise control as early as

possible. It is a complex discipline and a simple review of the initial layout

can save a lot of future headhaches.

• Nevertheless, there are some practical mitigation measures that can be

applied even during construction or in service.

• The NORSOK S-002 standard provides some good guidance and

methodology for noise control.

Lloyd’s Register Energy Conference

Safety-driven performance 2012

For more information, please contact:

Philippe Loustauengineering manager

Lloyd’s Register Energy Americas, Inc.

1330 Enclave Parkway, Suite 200

Houston, Texas 77077

T +1 281 649 2259

E [email protected]

w www.lrenergy.org

Lloyd’s Register Energy Conference

Safety-driven performance 2012

Lloyd’s Register Group Limited, its affiliates and subsidiaries and their respective directors, officers, employees, or agents, individually and collectively, are referred to here as “Lloyd’s Register.” Lloyd’s Register assumes

no responsibility and will not be liable to any person for any loss, damage, or expense caused by reliance on the information or advice provided in this document or in any other manner, unless that person has signed a

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