Section 1 Cargo or Product Transfer Systems

Ch 4

101. General

The requirements of this Section are applicable to the cargo or product transfer system and asso- ciated components of single point moorings. The cargo or product transfer system includes all sys- tem components from the seafloor connection to a pipeline to the first flange on the loading tanker or other type of unit. Pipe Line End Manifolds (hereinafter referred to as "PLEM"), if provided, are to comply with the requirements of this Section.

102. Conditions applicable to pipeline connection

The following conditions apply to the PLEM or connection between the undersea pipeline and the underbuoy hoses/flexible risers.

1. It is to be anchored to the sea bottom to resist forces due to waves, current, and forces im

posed by the SPM and the undersea pipeline.

2. A means of closure is to be provided to permit isolation of the SPM from the undersea pipeline.

103. Materials

Materials for cargo or product transfer systems are to comply with the requirements of Ch 2, 104.

of the Guidances.

104. Hoses/flexible risers

1. General

The length of the hose/flexible riser system, provision for buoyancy, spreaders between hoses/flexi- ble risers, external restraints (if required) and angle of connection to the pipeline end and the SPM are to be established taking into account at least the following.

(1) Maximum excursion of the SPM structure both under the operating conditions with a moored vessel and the design conditions without a moored vessel.

(2) Motion of the components of the system.

(3) External forces on the hose/flexible riser system.

(4) Range of specific gravity of the contents of the hose/flexible riser system including the various cargoes anticipated and sea water.

2. Underbuoy hoses/flexible risers

The system is to be designed to avoid chafing of underwater hoses/flexible risers due to contact

with the SPM hull or buoy, anchor legs or applicable mooring system, seabed, ses/flexible risers (if any). System designed with wear protection against incidental in design storm condition will be specially considered. Checking of designs for

and other ho- seabed contact interference is

required. Adequately reinforced hoses/flexible risers in areas of maximum hose/flexible riser flexing are to be provided. The procedures for installation, removal (if applicable), and maintenance are to

be submitted for review.

3. Floating hoses

Lifting arrangements are to be provided at the end of the floating hose. Special hose is to be pro- vided at the vessel end to accommodate the bending of the hose over the vessel rail (Tanker Rail Hose). The vessel end of the hose is to be provided with a blind flange to avoid contamination of the sea water. Consideration is to be given to providing swivels, specially reinforced hose, or both, at the connection of the floating hose with components of the SPM system. Consideration is to be given to providing a breakaway coupling with shut off valves in each floating hose string to pro- vide surge and axial overload protection to the hose string, and to minimize pollution in the event of an excessive pressure surge or tanker breakout.

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4. Construction

All hoses are to comply with the OCIMF "Guide to Purchasing, Manufacturing and Testing of Loading and Discharge Hoses for Offshore Moorings" (hereinafter referred to as "OCIMF Guide") and is to be manufactured to the Society. Prototype hose approval in accordance with Part B of this standard is required.

Variances from the OCIMF Guide as required to satisfy the system's operating conditions will be considered on a case by case basis. Adequate justification for such variances will be required. The bolting and gasket materials and design are to comply with an applicable design standard deemed by the Society and be suitable for their intended service.

Flexible risers, if utilized, are to meet the requirement found in API RP 17B "Recommended Practice for Flexible Pipe".

5. System design pressure

Design pressure is defined as the larger of:

(1) The shut-off head at the vessel's manifold at zero flow, plus the gravity head of the contents to the part of the SPM pipe or hose in question.

(2) The head calculated due to surge pressure, resulting from design valve closing times.

6. Testing

Each length of hose is to be subjected to hydrostatic and vacuum tests in accordance with require- ments of 1.11.6 and 1.11.8 respectively of the OCIMF Guide. These tests are to be witnessed by a Surveyor. In all cases where the design pressure of the system exceeds 15.5 bar, the hydrostatic test is to be carried out at not less than the design pressure. Where flexible risers are used, they are to be tested using standards deemed by the Society.

105. Cargo or product swivels and related systems and equipment

1. Cargo or product swivels

(1) Design

Cargo or product swivels are to be of steel construction with flanged or welded connections. Details of the swivel connecting stationary SPM piping with rotating piping are to be submitted for approval. Such details are to include fixed and rotating parts details, plate thicknesses, noz- zle locations and arrangement seal and bearing design, and welding. The swivel design is to consider the most adverse combination of applicable loads. At least the following loads are to be considered:

(A) Breakaway torque required for each swivel at maximum design pressure

(B) Weight of swivel and its structural components

(C) Dynamic loads due to vessel motion

(D) Piping loads

(E) Mooring forces

(F) Pressure loads

(G) Thermal loads

Pressure

retaining components of the swivel are to be designed in with a standard deemed

appropriated by the Society such as the ASME Boiler and Pressure Vessel Code. Structural

components of the swivel and driving mechanism are to comply with Ch 3, Sec 3 of the Guidances, the ASME code or other structural design standard deemed appropriated by the Society.

(2) Testing

Testing is to be conducted at the manufacturer's plant in accordance with an approved test pro- cedure in the presence of a Surveyor. The procedure is to address acceptable leakage criteria

and is to specify the following tests as a minimum:

(A) Hydrostatic pressure test to at least 1.5 times the design pressure for at least 2 hours.

(B) Hydrostatic pressure test to design pressure through 2 complete revolutions in each direction at a rate of approximately ten 10 minutes per revolution.

(C) Hydrostatic pressure test tion is to be clockwise,

to design pressure through 4 complete revolutions. The first revolu- and the final counterclockwise. Each rotation is to be in stages of

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30 degrees at a rate of approximately 30 seconds per 30 degrees with a 30 second pause between each 30 degree rotation. For each 30 degree rotation, the breakaway torque and the rotating torque are to be recorded. Where fluid assembly swivel rotates in unison with mooring swivel, this test is to be conducted on the combined system.

2. Leak monitoring, recovery and pressurization system

All piping for leak recovery and pressurization systems is to be of steel construction or equivalent and designed in accordance with ASME B31.3. A pressure balanced, or over-pressured, isolation seal is to be used between the primary seal and the product in gas or gas containing production fluid swivels.

3. Bearings

(1) Mooring bearings

Bearings which carry the operating hawser load, rotating structure load and mooring load are to be designed with a safety factor of not less than 2 without destructive yielding of the bearing surfaces.

Bearing mounting bolts are to be designed in accordance with standards deemed by the Society. For high tension bolts stress corrosion cracking is to be considered.

(2) Swivel bearings

Swivel bearings that do not carry the hawser load are to be designed in accordance with AFBMA (anti friction bearing manufacturers association) Codes or other industry standards

deemed appropriated by the Society.

4. Corrosion protection

The swivels are to be coated on the outside with a suitable corrosion resistant coating. This coating will not be required for parts made of corrosion resistant material. The possibility of corrosion due to the presence of CO2, O2, or H2S in the cargo or product fluid is to be considered in the swivel design.

106. Cargo or Product Piping Systems

1. Piping

All pipings for the cargo or product transfer system mounted on the SPM are to be of steel with welded or flanged connections. Piping is to be securely mounted on the SPM and anchored to re- sist the forces resulting from internal pressure and flow in the system and loads induced by the hose/flexible riser system connected to it. Provision is to be made for expansion. Piping is to be

shop tested after fabrication to a ence of the Surveyor.

Cargo or product piping installed less than standard weight should

minimum pressure of 1.5 times the design pressure in the pres-

on the SPM is to comply with ASME B31.3 except that piping not be used. Standard weight pipe is defined as the American

National Standards Institute Schedule 40 up to a maximum wall thickness of 9.5 .

2. Valves

A shut-off valve is to be provided on the SPM for each cargo transfer line. Valves are to be of steel construction and capable of manual operation. Valves are to be constructed and tested in ac- cordance with standards deemed appropriated by the Society such as those of the American National Standards Institute. Non-standard valves are those valves that are not certified as comply- ing with a standard deemed by the Society. The use of non-standard valves is subject to special consideration and drawings of such valves showing details of construction and materials are to be submitted for review, as well as the basis for valve pressure rating, such as design calculations or appropriate burst test data.

3. Flanges and fittings

Flanges and fittings are to be constructed and tested in accordance with standards deemed appro- priated by the Society such as those of the American National Standards Institute. Non-standard

flanges and fittings are those components that are not certified with a standard deemed appropriated by the Society. The use of

by the manufacturer as complying non-standard flanges and fittings is

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subject to special consideration and drawings of such components showing details of construction, materials and design calculations or test results are to be submitted for review.

4. Expansion joints

Expansion joints are to have a maximum allowable working pressure of no greater than one third of the hydrostatic bursting pressure of the joint. For non-metallic expansion joints, cross sectional

drawings of the joint showing construction of the joint including end fitting

attachment and a bill

of materials

are to be submitted for review. For metallic bellows expansion

joints, cross sectional

drawings of

the joint along with a bill of materials are to be submitted for review. Calculations

verifying that the expansion joint has been designed in accordance with the Expansion Joint

Manufacture's Association (EJMA) Standards or other applicable codes or standards deemed appro- priated by the Society, and is suitable for its intended use are also to be submitted for review.

5. PLEM piping

The requirements of Par 1 to 3 above are also applicable to the piping, valves, flanges and fittings forming the PLEM.

6. Corrosion protection

The cargo or product piping, valves and fittings are to be coated on the outside with a suitable corrosion resistant coating. This coating will not be required for parts made of corrosion resistant material. The possibility of corrosion due to the presence of CO2, O2 or H2S in the cargo or prod- uct fluid is to be considered in the piping design.