Noise management in offshore installations

Lloyd’s Register services to the energy industry

November 11-14, 2014 Adipec

Daniel Alvarez, M.Sc.

Senior Consultant, Energy

Lloyd’s Register

Noise Management in Offshore Installations



Noise

• Source of: stress, high blood pressure, headaches, tiredness, reduction of work efficiency, hearing loss

• May be fatal if personnel cannot hear instructions or alarms.

• Impacts: (1) comfort, (2) working conditions and (3) environment

Offshore Installations

• Compact environment with large amount of noise and vibration sources

• Structure-borne noise play an important role in steel-type structures

• Indoor controlable climate is often required

• Limited space and weight for noise control measures

• Movable facilities may want to comply with regulations globally



Successful Noise Management through...

• Understanding the targets

• Dialogue contractors - vendors

• Find optimal combination of noise control measures

• All based on Reliable Noise Predictions at early design stage

Value

• Substantial reduction of cost

• Enhance reduction by tailoring control measures to specific

design

• Minimize risk of expensive retroactive noise control



Noise Prediction Package often includes...

• Outdoor sound propagation study

• Noise at indoor machinery areas

• Noise Insulation Analysis

• Structure-borne noise study

• Evaluation of HVAC Noise

• Vibration studies

• Underwater noise study

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

0

1

2

3

4

5

6

7

8

9

10

11

X (Meter)

Y (M

eter)

108-110

106-108

104-106

102-104

100-102

98-100

96-98

94-96

92-94

90-92

88-90

86-88

84-86

82-84

80-82

78-80

76-78

74-76

72-74

70-72

FWD

Vacuum Unit

Skimmer Tanks

TriptankSand Trap

TankDegasser

Tank

Des

ilter

Tan

k

Cen

trifu

ge

Tan

k

Cat

ch T

ank

Cle

an T

ank

Triptank Pumps Desilter Pumps

Shearing Tank

Shearing Tank Slurry Tank

“The matter is not only to operate them, but to choose the right tool for specific applications”



Outdoor Sound Propagation Study• Focus on working conditions

• Identifies problem areas and warning signal locations

• Requires knowledge about oil & gas machinery and its noise and vibration characteristics (database)

• Can be used during the entire life cicle for HSE purposes (requires regular updates)

• Allows the evaluation of noise control measures



Noise at Indoor Machinery Areas• Focus on working conditions

• Identifies problem areas and warning signal locations

• Requires database of machinery noise and vibration characteristics as well as indoor environment properties (Absorption or T60)



Noise Insulation Analysis

Lp,1 Lp,2 = ?

• Focus on Accommodation Blocks and sensitive areas in noisy environments (control rooms)

• Noise transmission from outdoors as well as noise transmission amongst indoor spaces

• Requires knowledge about material properties (often based on empirical information)



Structure-borne Noise Study• Focus on Accommodation Blocks

• Requires source strength (energy to structure)

• Requires information about how the energy propagates in the structure (empirical or statistical)

• Requires knowledge in regards to material damping (often flooring)

Lv1

Lv2 Lv3

Lv4

LW2

LW1

LW4

LW3



Evaluation of HVAC Noise

• Focus on Accommodation Blocks and often affecting working conditions too

• Noise is generated through supply and return ducting (silencer up and downstream)

• Silencers are often cheap solutions but often forgotten creating a space issue

• Empirical information about pressure-drop control devices is often required



Vibration Studies• Deterministic analysis of supporting structure

• The output refers structural modifications to suit requirements

• Often conducted only for major equipment

Excitation points:



Vibration Studies (2)• Coarse evaluation of suporting structure

• Selection of anti-vibration mounts as per machinery characteristics

• Database of anti-vibration technology plays an important role



Underwater Noise Study• The effect of piling of offshore platforms

Overa

ll SEL

(dB

re 1

µPa2s

)

Depth

[m

]

Range [km]1 2 3 4 5 6 7

10

30

50

70

90

180

170

160

150

140

130

120

Seabed

Source



Underwater Propagation Modelling

Acoustic Finite Element Model of untreated pile vs single-wall cofferdam

Snapshot at 19 ms

Hammer energy 1890 kNm/kJ

Pile length/diameter: 45 m / 5.4 m

Water depth: 25 m

Cofferdam: 50 mm steel, 900 mm air gap

Water Water

Seabed Seabed

Cofferdam

Water-filled pile



Conclusions

• Noise may cause significant costs in your project

• Noise may generate considerable damage to your employees

• Theoretical and empirical information in regards to noise and vibration charateristics of machinery, as well as material noise insulation properties play an important role during the design

• Noise and vibration prediction tools help to evaluate your asset. The matter is not only to operate them, but to choose the right tool for specific applications

• The earlier noise is considered, the better!


Documents

Noise management in offshore installations