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. Door Vibration exposure Equipment vibration (rigid mounting) Floor Lining panel Window Ceiling HVAC (extract) HVAC (supply) Partition panel (towards corridor) partition panel (towards desk) 0 10 20 30 40 50 60 70 80 90 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 )
Examples of recommendations living quarters Partition panels covered with steel plate in test cabin Actual panel not performing according to spec Mock up cabin built for testing
Example of recommendations Utility area Air exhaust - silencers Additional silencers Air exhaust and inlet on main deck injection fans - exhaust line
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 deck On top of some cabins
Example of recommendations Utility area Hvac extracts - silencer Silencer HVAC extract on top of driller s cabin used to avoid the noise from drill floor to the cabins
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.
For more information, please contact: Philippe Loustau engineering manager Lloyd s Register Energy Americas, Inc. 1330 Enclave Parkway, Suite 200 Houston, Texas 77077 T +1 281 649 2259 E philippe.loustau@lr.org w www.lrenergy.org 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 contract with the relevant Lloyd s Register entity for the provision of this information or advice, and in that case any responsibility or liability is exclusively on the terms and conditions set out in that contract. ModuSpec USA, Inc. and its affiliates are a subsidiary of Lloyd s Register.