Section 2 Design

201. General

The design of the import and export system is to consider all modes of operating, testing, survival and accidental events. The import and export system is to be analyzed to determine its response to the design events. Each individual component is to be examined for its strength and suitability for the service conditions.

202. Rigid risers

1. The analysis of a rigid riser is to follow the appropriate sections of API RP 2RD and API RP 2T for all relevant design load cases.

2. The following items are to be appropriately accommodated in the analysis:

(1) Environmental conditions

(2) Boundary conditions

(3) Riser configuration

(4) Riser joint properties

(5) Buoyancy devices

(6) Installation motion (RAOs)

(7) Applicable site conditions

(8) Effects of internal contents

(9) Pressure testing and accidental conditions

2. Rigid risers are to be designed against the following limits based on the design load cases being investigated.

(1) Maximum Stress, Stability and Buckling: Allowable stresses in plain pipe are to be limited, per API RP 2RD. Overall stability of the riser and local pipe buckling is to be evaluated.

(2) Maximum Deflection: Acceptable limits of maximum deflection are to be determined considering

the inherent limitations of riser components, equipment used in the riser and the need to avoid

interference with the Floating Installation.

(3) Fatigue and Fracture: The riser system is to be designed to ensure that an adequate margin of safety is available for critical components to counteract the effects of fatigue caused by cyclic fluctuations (due to both internal and external loads) over the anticipated life of the system.

(4) The cumulative damage calculated by the use of Miner’s Rule is to be 0.1 or less for a critical component which cannot be easily inspected or repaired. For non-critical components which can be easily inspected, the cumulative damage should be 0.3 or less.

203. Flexible risers

1. The in-place analysis is to address all design load cases using motions consistent with the mooring analysis.

2. The scope of the in-place analysis, as a minimum, is to include the following:

(1) On-bottom stability for flexible flow lines

(2) Static and dynamic analysis for flexible riser

(3) A system dynamic analysis to ensure:

(A) Maximum tension and minimum radius of curvature are within the manufacturer’s recom- mendations

(B) Suspended portions of the flexible pipe are not allowed to bounce on the sea floor or expe- rience compression that might cause kinks

(C) Suspended flexible pipes are not allowed to chafe against each other, the installation body or mooring lines

(4) Flow-induced motion analysis

(5) Flexible pipe layer stress analysis

(6) The stresses in the flexible pipe layers are to comply with the requirements of API Spec 17J for the applicable design load cases

(7) Mechanical gripping devices should not cause damage to the weaker exterior layer

(8) Service life analysis

(9) Corrosion protection system design

3. Design limits established for the riser system are to be determined in accordance with API RP 17B and confirmed by performance testing during the manufacture of the flexible riser and the asso- ciated components. Where sufficient test data and service history exist to confirm a component’s capability, the Society may consider the acceptance of this documentation in lieu of performance testing.

204. Floating hose

In cases where floating hoses are used to transfer the crude oil from the production unit to carrier or another units, such floating hoses are to comply with the following requirements.

(1) Breakaway couplings are to be provided with shut off valves in each floating hose string in or-

der to minimize the hazard of oil pollution in emergency situations.

(2) Floating hoses are to comply with recognized standard (OCIMF, API, hold appropriate certificates for necessary tests and inspections.

(3) The construction of connections between hoses and the unit (bolting,

suitable for their intended service.

MARPOL, etc.), and to

gaskets, etc.) are to be