API 2FP1 : 1993

RECOMMENDED PRACTICE FOR DESIGN, ANALYSIS AND MAINTENANCE OF MOORINGS FOR FLOATING PRODUCTION SYSTEMS

American Petroleum Institute

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Policy
Foreword
Section 1. Basic considerations
1.1 Introduction to mooring of floating
a. Spread mooring
b. Single point mooring
c. Dynamic positioning
1.2 Differences between mooring systems for FPS and
MODU
a. Type of mooring
b. Environmental criteria
c. Method of analysis
d. Mooring hardware
e. Installation
f. Inspection and maintenance
1.3 Design considerations
a. Primary design considerations
b. Riser considerations
c. Subsea equipment considerations
Section 2. Mooring component
2.1 Mooring line
a. Classification
b. Chain
c. Wire mooring line
d. Synthetic mooring line
e. Clump weight
f. Spring buoy
g. Connecting hardward
2.2 Winching equipment
a. Windlass
b. Chain jack
c. Drum type winch
d. Linear winch
e. Traction winch
f. Fairlead and bending shoe
2.3 Anchoring system
a. Drag embedment anchor
b. Anchor pile
c. Caisson foundation
d. Gravity anchor
e. Propellant embedment anchor
Section 3. Environmental criteria
3.1 Environmental condition
a. Maximum design condition
b. Maximum operating condition
3.2 Environmental data
3.3 Wind
3.4 Waves
3.5 Current
3.6 Water depth and tide
3.7 Soil condition
3.8 Atmospheric icing
3.9 Marine growth
Section 4. Environmental loads and vessel motions
4.1 Basic considerations
4.2 Current
a. Model tests
b. Current force calculations
4.3 Waves
a. Model tests
b. Wave frequency vessel motions
c. Mean wave drift force
d. Low frequency vessel motions
4.4 Wind
a. Model tests
b. Wind force calculation
4.5 Oblique environment
Section 5. Design criteria
5.1 Vessel offset
a. Definition of mean offset
b. Definition of maximum offset
c. Offset limits
5.2 Mooring analysis
a. Definition of mean tension
b. Definition of maximum tension
c. Tension criteria
5.3 Statistics of peak values
5.4 Line length
5.5 Holding power of anchoring systems
a. Drag anchor
b. Chain and wire rope
c. Anchor pile
d. Caisson foundation and gravity anchor
e. Mooring test load
5.6 Thruster assisted mooring
5.7 Fatigue life
Section 6. Mooring analysis
6.1 Basic considerations
a. Extreme response analysis
b. Fatigue analysis
6.2 Extreme response analysis procedure
a. Analysis for mooring system without thruster assist
b. Analysis for thruster assisted mooring
6.3 Fatigue analysis procedure
Section 7. Model testing
7.1 Basic considerations
Section 8. Inspection and maintenance
8.1 Basic considerations
8.2 Inspection procedure and frequency
a. Above surface mooring line
b. Underwater fairleads
c. Submerged section of mooring line
d. Mooring line terminations and connection hardware
e. Submersible buoys
8.3 Example inspection program
Section 9. Design example
9.1 Extreme response analysis example
a. Mooring system description
b. The environment
c. Mean load computation
d. Vessel/fairlead motions
e. Mooring analysis results
9.2 Fatigue analysis example
a. Mooring system description
b. Environmental conditions
c. Fatigue analysis
d. Fatigue damage
References

Abstract

Presents a rational method for analyzing, designing, or evaluating mooring systems used with floating production systems (FPS). This method provides a uniform analysis tool which, when combined with an understanding of the environment at a particular location the characteristics of the unit being moored, and other factors, can be used to determine the adequacy and safety of the mooring system. Guidelines for inspecting and maintaining Floating Production Systems mooring systems are also included.