INTRODUCING

DNV RP E305

ON BOTTOM STABILITY

Concrete Coating Thickness Calculation

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DNV RP E 305

Design, organize, and collaborate

Design Data

Load Case

Methodology

Concrete Coating Thickness Calculation

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DESIGN DATA

Collect Information

Concrete Coating Thickness Calculation

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DES

IGN

DA

TA

PIPELINE PARAMETER

OUTSIDE DIAMETER

WALL THICKNESS

MINIMUM FLUID

DENSITY

CORROSION COATING

WEIGHT COATING DENSITY

Concrete Coating Thickness Calculation

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DES

IGN

DA

TA ENVIRONMENT DATA

GEOPHYSICAL DATA

WATER DEPTH

TIDAL STORM SURGE

CURRENT VELOCITY (1 Yr, 10

Yr, 100 Yr)

WAVE

Significant Wave

Height (Hs)

Spectral Peak

Period (Tp)

GEOTECHNICAL DATA

SAND SOIL

GRAIN SIZE UNDRAIN

SHEAR STRAIN

Concrete Coating Thickness Calculation

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Load Case

DNV RP E305

Concrete Coating Thickness Calculation

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LOAD CASE

INSTALLATION CONDITION

10 YR WAVE + 1 YR

CURRENT

1 YR WAVE + 10 YR

CURRENT

OPERATING CONDITION

100 YR WAVE + 10

YR CURRENT

10 YR WAVE + 100 YR CURRENT

Concrete Coating Thickness Calculation

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METHODOLOGY

DNV RP E305

Concrete Coating Thickness Calculation

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DNV RP E305

DYNAMIC ANALYSIS

GENERALISED STABILITY ANALYSIS

SIMPLIFIED STABILITY ANALYSIS

METHODOLOGY

ON BOTTOM STABILITY

DESIGN CRITERIA

Vertical: (WS+B)/B=1.1

Lateral: [WS/FW - FL]m ≥ FD+FI

Concrete Coating Thickness Calculation

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DES

IGN

MET

HO

D Concrete Coating Thickness Calculation

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GENERAL CALCULATION Concrete Coating Thickness Calculation

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WAVE CALCULATION d: Water Depth

TP: Spectral peak period of surface spectrum

HS: Significant wave height

US*: Significant velocity perpendicular to the pipe

Figure 2.1: Significant Water Velocity

Determine US:

US = US* x R (Page 9)

Where:

US: Significant velocity perpendicular to the pipe

R: Reduction factor

Concrete Coating Thickness Calculation

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WAVE CALCULATION TP: Spectral peak period of surface spectrum

TU: Mean Zero Up Crossing Period

Figure 2.2: Zero-Up-Crossing Period

Keulegan - Carpenter number

K = (Us.Tu)/Dt

Significant acceleration

AS = 2π.US/TU (page 28)

Current & Wave velocity ratio

M = UC / US

Concrete Coating Thickness Calculation

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CALIBRATION FACTOR

Figure 5.12: Calibration Factor FW as function of K and M

Concrete Coating Thickness Calculation

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FRICTION FACTOR

Figure 5.11: Recommended

Friction factor m

Concrete Coating Thickness Calculation

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CURRENT CALCULATION

Where:

Ur = Near Bottom Current Velocity

UD = Average velocity over pipe diameter

z = Elevation above seabed

z0 = Bottom roughness parameter

zr = Reference height above seabed

Concrete Coating Thickness Calculation

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HYDRODYNAMIC LOAD Concrete Coating Thickness Calculation

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Required Submerge Weight Sufficient to Environment Load

Submerge Weight Based on Initial Concrete Thickness

Concrete Coating Thickness Calculation

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WAVE THEORY

• Airy : Most appropriate for small wave amplitudes where linear (1st order) theory applies. It may also be applicable for large amplitudes for pipes at sea bottom.

• Stokes: This is Stokes 5th order. Can be used for larger wave heights and is applicable for stokes waves up to 5th order.

• Stream: Can be used for very high amplitude and breaking waves up to 10th order.

• Current: Restricts wave loading to current effects only. No wave action. In this case, wave period and height are not used, but water depth is used to limit the current data to points above sea bottom.

Concrete Coating Thickness Calculation

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WAVE THEORY

Concrete Coating Thickness Calculation

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SPECTRAL DENSITY

LINEAR WAVE THEORY

SPECTRAL DENSITY

FREQUENCY TRANSFER FUNCTION

SPECTRAL MOMENTS OF ORDER n

SIGNIFICANT FLOW VELOCITY AMPLITUDE AT PIPE LEVEL

MEAN ZERO UP-CROSSING PERIOD

REDUCTION FACTOR

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THANK YOU FOR YOUR ATTENTION!

QUESTION… ? DNV RP E305

Concrete Coating Thickness Calculation

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