M \2009 03 04\~$blank pdf BS EN 1474 2 2008 ICS 75 200 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW BRITISH STANDARD Installation and equipment for liquefied natural gas — De[.]
A LNG transfer hose system shall consist of the following
A flexible hose assembly, comprising
associated end terminations and connectors;
hose handling device(s) (padeye or lifting lugs, lifting collar, …), and if required:
insulation system (to minimize build up of external ice);
Connection system to LNGC
Hose extremity connector flanges shall permit the mounting of a QCDC or a spool piece or permit direct connection to LNGC or LNG terminal or another hose assembly
(A description of QCDC is given in EN 1474-1, for transfer system reference is made to EN 1474-3)
Hubs, or other connectors if equivalent or superior to flanges, may be used if agreed between owner and vendor.
Emergency release system
Hose extremity connector shall permit the mounting of an emergency release system with valves and ERC (Emergency Release Coupler)
(A description of emergency release system is given in EN 1474-1 and EN 1474-3).
Handling
Hoses must be equipped with essential fittings to ensure safe handling and facilitate the coupling and uncoupling processes from the LNG carrier (LNGC) or the onshore or offshore LNG terminal system, in accordance with the system design outlined in EN 1474-3.
Power systems
Hose may support (e.g piggy back mounted) hydraulic or pneumatic hoses, electric cables for the powering of the ERS and QCDC systems (refer to EN 1474-1:2008, Clause 6).
Leak detection, monitoring and alarm systems
If required by the owner the hose shall incorporate leak detection system e.g gaseous nitrogen bleeding in the annular space (see 5.11).
Typical construction of LNG transfer hoses
Main hose categories
At present LNG transfer hoses are categorized in two types according to their method of construction:
those based on a reinforced corrugated metal hose construction, hereafter called corrugated metal hose;
those based on a construction in which polymeric films and fabrics are entrapped between a pair of close wound helical wires, hereafter called composite hose;
as the technology develops, other types of hose may become available and are also to be considered covered by this European Standard.
Corrugated metal hoses
The inner layer is made of stainless steel corrugations (sometimes called bellows) This ensures the inner leak- proofness of the structure, as well as sustaining the inner radial pressure
These armour layers support the axial loading whilst providing an initial thermal insulation
This layer ensures that the armours remain in place, as well as providing some thermal insulation
This layer (or series of layers) ensures that the inner temperature is conserved whilst preventing any build-up of ice on the exterior of the hose
Intermediate and outer leak-proof layers
The intermediate sheath of the hose creates a double annulus, enabling immediate detection of any LNG leaks Additionally, the external sheath effectively prevents water from entering from outside.
The hose assembly construction shall ensure that all materials are used within their individual range of temperature
Figure 1 — Typical hose assembly – reinforced corrugated metal hose family
The outer leak-proof layer can be designed as a corrugated stainless steel pipe, similar to the inner pipe, with the annular gap between them potentially evacuated Monitoring the pressure in this annular gap allows for effective leak detection of both the inner and outer pipes Additionally, thermal insulation can be preserved through layers of super insulation within the evacuated annular space.
Figure 2 — Typical hose assembly – Sketch of a LNG flexible hose with vacuum insulation option
The end fitting assembly is made of stainless steel, and ensures 2 primary functions
The flexible termination integrates various layers, maintaining the integrity of each layer at its end This construction enables the prompt detection of any LNG leaks within the inner annulus.
The end connector is connected to the associated piping at each end of the flexible This will typically be a standard ANSI flange.
Composite hoses
A composite hose is made up of several un-bonded layers of polymeric film and fabric, secured between two wire helices that maintain its shape The film layers create a fluid-tight barrier for the transported product, while the fabric layers ensure the hose's mechanical strength.
The construction sequence begins with a bore, featuring an inner metallic wire helix applied at a predetermined close pitch This is followed by layers of polymeric fabric that form the bore material, along with a pack of multiple polymeric film layers that create a tubular structure, ensuring a fluid-tight barrier for the conveyed product Next, a pack of polymeric fabric layers is added to reinforce the hose, and finally, an outer metallic wire helix is applied at a half-pitch offset to the inner wire under tension, resulting in the desired convoluted structure of the hose.
The configuration and quantity of layers in steps c) and d) are tailored to the specific hose size and its intended use Additionally, the chosen polymeric film and fabric materials are designed to ensure compatibility with the conveyed product and withstand extreme operating temperatures.
Figure 3 — Typical hose – composite hose family
5 Design features of the LNG transfer hoses and transfer hoses assemblies
General
The hose is a crucial component of the LNG transfer system, with its design dictated by specific requirements such as static load and dynamic movements, as detailed in EN 1474-3 The following outlines the design process and necessary information.
Application data required
The application data required should be determined by the owner and/or the system vendor according to the guidelines given in Annex A.
Selection of hose length
The total length of the hose is determined by the system design and must adequately accommodate both storage and operational requirements, including the motion envelopes specified in EN 1474-3 (refer to Annex A).
The hose can be provided as a continuous length or in discrete sections, depending on factors such as its length, system design, type, and shipping requirements.
The hose length used in the system shall be such that the motion envelopes as defined in EN 1474-3 are met (see also Annex A)
Hose length shall take into account the elongation of the hose under pressure and its own weight This elongation shall be consistent with the transfer system design.
Service life
The required service life shall be agreed between the owner and the vendor
The service life of a hose is determined by various factors, including the cumulative impact of flexure, tensile, pressure, and temperature cycles during operation, as well as environmental aging and the effects of emergency disconnections and internal pressure surges.
The safety ratio between service life, fatigue life and fatigue test duration shall be agreed by the owner and the vendor and shall be documented.
Selection of hose size
The owner must define the flow rate, maximum allowable working pressure, temperature, product composition, and maximum allowable head loss Additionally, the number of hoses can either be predetermined by the system or customized to meet specific size and flow rate requirements.
The vendor shall confirm the Maximum Allowable Working Pressure (MAWP) of the hose assembly to allow the owner to size pressure relief devices etc.
Selection of buoyancy
The transfer system must ensure that the hose is either floating or aerial, or the owner must specify the required degree of buoyancy, including any submersion requirements.
If buoyancy is required, it shall be agreed between the owner and the vendor.
Selection of insulation
If required the hose shall have sufficient insulation to minimize build-up of ice on the exterior of the hose itself and to limit heat leak.
Basic design parameters
The MBP (Minimum Burst Pressure) ratio to the MAWP is given in Clause 6
The FAT (Factory Acceptance Test) pressure is given in Clause 6
The maximum flow velocity in the hose shall be agreed by the owner and the vendor
Maximum allowable applied twist shall be specified by the vendor
The hose shall be designed ensuring the compatibility of each component (layer) of the hose with its function (e.g LNG and NG service and testing values).
Component details – End fitting
General
The end fittings of any hose comprise of two main parts:
Illustration of an end fitting (typical, may vary depending on the hose design):
Figure 4 — Typical end fitting assembly – composite hose family
Termination
The termination shall ensure the following functions:
mechanical attachment of all component layers of the hose which resist against internal pressure, traction and torsion;
provide a leak-proof seal against the transported fluid and/or gas;
provide a leak-proof seal against ingress of humidity or water from the outer environment
The end fitting shall comply with the system fatigue criteria
In the case of a burst test for proof purposes, the end fittings shall not separate from the hose.
Connector
The connector must be either machined into the end termination or welded according to a qualified procedure The owner and/or system requirements will specify the type of connector needed.
Bending stiffener/restrictor (optional)
An optional component, which can be either embedded in or mounted onto the hose at one or both ends, serves to ensure a smooth transition of bending forces from the end fitting to the hose structure This feature enhances the hose's resistance to over-bending, thereby improving its durability and performance.
The inclusion of a bend stiffener is at the vendors discretion following review of the operational conditions.
Hose handling / lifting device
The design of additional components like hose handling devices (pad eyes or collars), QCDC, and ERS must align with the specific system requirements and comply with EN 1474-1 and EN 1474-3 standards Furthermore, detailed hose handling instructions should be provided as an integral part of the system.
Appropriate hose handling instructions shall be supplied with each order to allow correct handling during transport and at others times prior to inclusion in the system
A hose handling and lifting device must be engineered and rigorously tested to ensure the safe management of the entire hose Upon request and with mutual consent between the vendor and the owner, the device can also be customized to accommodate additional equipment that may be connected to either end of the hose.
Appropriate arrangements are to be provided to securely keep the hoses in stored position when not in service or whilst being transported.
Safety systems
Gas detection systems, when installed, serve as a crucial warning mechanism for hose leaks, enabling timely and appropriate responses The system must comply with specified standards.
The leak detection system focuses solely on the inner pipe If a break occurs in the inner pipe, the supervision system triggers an alarm signal to the terminal; however, natural gas (NG) can still escape into the environment.
leak detection only at the end fitting to provide detection of seal failure;
The leak detection system monitors only the inner pipe, triggering an alarm at the terminal in the event of a break For minor leaks, the escaping gas is released through the annular gap, which cannot withstand the Maximum Allowable Working Pressure (MAWP) of the hose.
Leak detection is crucial for both the inner and outer pipes If a leak occurs in the outer pipe, an alarm is triggered at the terminal In the event of a leak in the inner pipe, the terminal also receives an alarm, while the escaping gas is contained by the outer pipe The outer pipe is designed to withstand the Maximum Allowable Working Pressure (MAWP) of the hose.
Not all hoses have an annulus running along their entire length In these cases a leak detection may be provided in the vicinity of the transition
Fire safety requirements, if specified shall be mutually agreed between owner and vendor, see also
Electrical continuity requirements shall be mutually agreed between the owner and the vendor, see also EN 1474-3:2008, 7.6.
Connection to the ship
The connection to the ship will be established through the manifold by utilizing the LNG hose assemblies, which are linked via their specific connections in the hose system, as outlined in EN 1474-3:2008, Clause 8.
Hydraulic and electric control systems
Any requirements for hydraulic and electric control system affecting the hose shall be specified by the owner (refer to EN 1474-1:2008, Clause 7)
All qualification test results shall be recorded in a written report that shall be presented by the vendor to the owner
This clause outlines the essential tests required, without providing a comprehensive description of the testing procedures, which can differ among various hose manufacturers and technologies.
As a general principle, all parameters / characteristics shall be verified by testing
Annex B (normative) "Prototype and factory acceptance tests for LNG hose assemblies" gives a summary of the tests to be performed
In Clause 6 the following definitions apply:
Non-destructive [ND] – a test that is not expected to cause permanent damage to the hose assembly, so that the hose may be used in subsequent tests
Destructive testing (D) involves procedures that lead to irreversible damage to the hose, necessitating dissection for evaluation This assessment focuses on the impact of the test on the hose's structural integrity and the reliability of its end terminations.
The Maximum Allowable Working Pressure (MAWP) refers to the highest gauge pressure that a hose can safely handle across its specified temperature range Terminals utilize this measurement to establish the pressure capabilities of their cargo systems, which includes factors such as pump shut-in pressure and static head or safety valve relief settings While the MAWP does not account for dynamic surge pressures, it does consider normal pressure fluctuations that occur during cargo transfer operations, in line with the IMO IGC Code.
1993 chapter 5.7.3” (complete reference is given in Bibliography) the specified MAWP shall not be less than 10 bar gauge Reference is made to Annex C for surge pressure considerations
Proof Pressure (PP) refers to the pressure at which a hose is tested to ensure its structural integrity under internal pressure, typically during a Factory Acceptance Test According to the IMO IGC Code, this pressure test must be conducted at ambient temperature and should be no less than 1.5 times the Maximum Allowable Working Pressure (MAWP) and no more than 40% of the hose's bursting pressure.
The Minimum Burst Pressure (MBP) refers to the lowest internal pressure at which a hose with sealed end caps will rupture, and it must be at least 5.0 times the Maximum Allowable Working Pressure (MAWP) at the highest service temperature.
NOTE This is in accordance with the IMO IGC Code (complete reference is given in Bibliography)
All test procedures and their parameters shall be in accordance with the vendor’s written test procedures
1) Ambient mechanical properties of all materials – ascertain that the mechanical properties of the materials are suitable for their intended application and within specification limits;
When selecting materials for applications at cryogenic temperatures, it is essential to evaluate their mechanical properties to ensure they are suitable for the intended use This assessment may be enhanced by incorporating data from suppliers, providing a comprehensive understanding of how materials perform under cryogenic conditions.
The impact of LNG exposure on materials operating at cryogenic temperatures must be evaluated to ensure that their mechanical properties remain unaffected or to quantify any changes within acceptable limits.
The impact of ambient climatic exposure on materials must be evaluated to ensure that such exposure does not negatively influence their performance throughout the hose's design life.
NOTE This test could be combined with test 5
The marine environment can significantly impact the corrosion of metallic components, affecting all exposed layers It is crucial to ensure that these environmental effects do not negatively influence the performance of materials throughout the hose's design life.
All test procedures and their parameters shall be in accordance with the vendor written test procedures
The ambient pressure and leak test [ND] is the initial test conducted to verify that the unrestrained hose assembly, equipped with end caps, can withstand its proof pressure without any leaks at ambient temperature.
A hydrostatic test at ambient temperature must be conducted for 4 hours after stabilization, with both temperature and pressure values recorded Any pressure changes that are directly related to temperature fluctuations are permissible Additionally, both temporary and permanent elongation should be documented.
The cryogenic pressure and leak test [ND] verifies that the unrestrained hose assembly, equipped with end caps, can withstand its proof pressure without any leaks at the lowest service temperature Additionally, both temporary and permanent elongation measurements will be documented.
Liquefied nitrogen test held for 4 h A leak detection monitoring device shall be used
Stiffness characterization tests, conducted at both ambient and cryogenic temperatures, are essential for evaluating hose performance Axial stiffness tests, which may be included in tests 9 and 14, measure the hose's axial stiffness across varying temperatures Additionally, bend stiffness tests, potentially part of tests 10 and 15, assess the hose's bend stiffness and confirm the minimum bend radii for both storage and working conditions at these temperatures.
The bending radius of a hose is measured at its center line Additionally, torsional stiffness tests can be performed to assess the hose's performance at both ambient and extreme low service temperatures.
The pressure cycle test (ND) conducted at ambient temperature verifies that the unrestrained hose assembly, equipped with end caps, can endure 200 pressure cycles, ranging from zero to at least double the specified Maximum Allowable Working Pressure (MAWP).
NOTE 2 This is in accordance with IMO IGC Code (complete reference is given in Bibliography)
5) Burst test [D] at ambient temperature (may be combined with test 1) – ensure that the minimum burst pressure is at least 5 times the MAWP
The hydrostatic burst test on the unrestrained hose assembly with end caps shall be carried out with a steady pressure increase to rupture A leak detection monitoring shall be used
6) Cryogenic burst test (may be combined with test 2) [D] – the minimum burst pressure is at least 5 times the MAWP
The cryogenic burst test on the unrestrained hose assembly with end caps shall be carried out with a steady pressure increase to rupture, using liquefied nitrogen
7) Ambient impact testing [D] – to quantify an impact load that the hose is capable of withstanding
8) Ambient crush testing [D] – to quantify a crush load that the hose is capable of withstanding
9) Ambient tensile test to MWL (Maximum Working Load) [ND] – confirm that the hose is capable of supporting its maximum working load whilst at MAWP
Laboratory testing
All test procedures and their parameters shall be in accordance with the vendor’s written test procedures
1) Ambient mechanical properties of all materials – ascertain that the mechanical properties of the materials are suitable for their intended application and within specification limits;
When selecting materials for applications at cryogenic temperatures, it is essential to evaluate their mechanical properties to ensure they are suitable for the intended use This assessment may be enhanced by incorporating data from suppliers, providing a comprehensive understanding of how materials perform under cryogenic conditions.
The impact of LNG exposure on materials operating at cryogenic temperatures must be evaluated to ensure that their mechanical properties remain unaffected or to quantify any changes within acceptable limits.
The impact of ambient climatic exposure on materials that are exposed to the atmosphere must be evaluated to ensure that such exposure does not negatively influence the materials' performance throughout the hose's design life.
NOTE This test could be combined with test 5
The marine environment can significantly impact the corrosion of metallic components, affecting all exposed layers It is crucial to ensure that these environmental effects do not negatively influence the performance of materials throughout the hose's design life.
Prototype hose testing
All test procedures and their parameters shall be in accordance with the vendor written test procedures
The ambient pressure and leak test [ND] is the initial test conducted to verify that the unrestrained hose assembly, equipped with end caps, can withstand its proof pressure without any leaks at ambient temperature.
A hydrostatic test at ambient temperature must be conducted for 4 hours after stabilization, with both temperature and pressure values recorded Any pressure changes that are directly related to temperature fluctuations are permissible Additionally, both temporary and permanent elongation should be documented.
The cryogenic pressure and leak test [ND] verifies that the unrestrained hose assembly with end caps can withstand its proof pressure without any leaks at the lowest service temperature Additionally, both temporary and permanent elongation measurements will be documented.
Liquefied nitrogen test held for 4 h A leak detection monitoring device shall be used
Stiffness characterization tests, including both ambient and cryogenic conditions, are essential for evaluating hose performance Axial stiffness tests, which may be integrated with tests 9 and 14, measure the hose's axial stiffness at various temperatures, including extreme low service temperatures Additionally, bend stiffness tests, potentially part of tests 10 and 15, assess the hose's bend stiffness and confirm the minimum bend radii for both storage and working conditions at ambient and extreme low temperatures.
The bending radius of a hose is measured at its center line Additionally, torsional stiffness tests can be performed to assess the hose's rigidity at both ambient and extreme low service temperatures.
The pressure cycle test (ND) conducted at ambient temperature verifies that the unrestrained hose assembly, equipped with end caps, can endure 200 pressure cycles, ranging from zero to at least double the specified Maximum Allowable Working Pressure (MAWP).
NOTE 2 This is in accordance with IMO IGC Code (complete reference is given in Bibliography)
5) Burst test [D] at ambient temperature (may be combined with test 1) – ensure that the minimum burst pressure is at least 5 times the MAWP
The hydrostatic burst test on the unrestrained hose assembly with end caps shall be carried out with a steady pressure increase to rupture A leak detection monitoring shall be used
6) Cryogenic burst test (may be combined with test 2) [D] – the minimum burst pressure is at least 5 times the MAWP
The cryogenic burst test on the unrestrained hose assembly with end caps shall be carried out with a steady pressure increase to rupture, using liquefied nitrogen
7) Ambient impact testing [D] – to quantify an impact load that the hose is capable of withstanding
8) Ambient crush testing [D] – to quantify a crush load that the hose is capable of withstanding
9) Ambient tensile test to MWL (Maximum Working Load) [ND] – confirm that the hose is capable of supporting its maximum working load whilst at MAWP
Hoses must be gradually filled to the Maximum Working Level (MWL) and pressurized hydrostatically to the Maximum Allowable Working Pressure (MAWP) During this process, hoses should be inspected for leaks while maintained at MWL and MAWP for 15 minutes Both temporary and permanent elongation must be documented, and there should be no visible damage.
The ambient bend test for Minimum Bend Radius (MBR) ensures that the hose can support its Maximum Allowable Working Pressure (MAWP) at the specified working MBR, which is measured to the center line of the hose.
Hoses must be gradually bent to the Maximum Bend Radius (MBR) and then pressurized to the Maximum Allowable Working Pressure (MAWP) During this process, the hose should be inspected for leaks while maintaining pressure for 15 minutes at the MBR Upon returning to pre-test conditions, no damage should be visible.
When a hose is not produced as a single continuous length, it is essential to test the connection between the hose and coupling under load conditions This testing should involve a hose coupling, ideally positioned at the midpoint of the hose length, to ensure accurate results The test must also induce the Minimum Bend Radius in the section of the hose that is closest to the flange.
11) Ambient twist to MAAT (Maximum Allowable Applied Twist) [ND] – confirm that the hose is capable of supporting its maximum working load whilst at MAAT
The hose must be hydraulically pressurized to its Maximum Allowable Working Pressure (MAWP) The twist angle should be adjusted to the Maximum Allowable Angle of Twist (MAAT), and the hose should be inspected for leaks while maintained at MAAT for 15 minutes There should be no visible external damage.
12) Cryogenic impact testing [ND] – To ensure that the specified ambient impact load that the hose is capable of withstanding without damage is still applicable at the minimum service temperature
13) Cryogenic crush testing [ND] – To ensure that the specified ambient crush load that the hose is capable of withstanding without damage is still applicable at the minimum service temperature
14) Cryogenic tensile test to MWL [ND] – confirm that the hose is capable of supporting its specified working load whilst at MAWP
The hose is pressurized with liquefied nitrogen to its Maximum Allowable Working Pressure (MAWP) The axial load is then increased to the Maximum Working Load (MWL), with the pressure adjustable for expansion During a 15-minute hold at MWL, the hose is inspected for leaks, ensuring no external damage is visible Both temporary and permanent elongation measurements are recorded.
15) Cryogenic bend test to MBR [ND] – confirm that the hose is capable of supporting its specified working load whilst at working MBR
The hose must be gradually bent to the MBR, cooled, and pressurized with liquefied nitrogen to its Maximum Allowable Working Pressure (MAWP) During this process, the hose should be inspected for leaks while maintained at MBR for 15 minutes Upon returning to ambient pre-test conditions, there should be no visible damage, including ovality or residual deformation.
16) Cryogenic twist to MAAT [ND] – confirm that the hose is capable of supporting its specified working load whilst at MAAT
The twist angle will be raised to the Maximum Allowable Ambient Temperature (MAAT) The hose will be pressurized with liquefied nitrogen to the Maximum Allowable Working Pressure (MAWP) and inspected for leaks while maintained at MAAT for 15 minutes, ensuring no damage is present.
The ambient to MAWP (Maximum Allowable Working Pressure) and minimum temperature cycle test is designed to verify the hose assembly's ability to endure temperature and pressure fluctuations This test requires a minimum of 20 combined cycles of pressure and temperature to ensure reliability and performance.
18) Cryogenic bending cyclic fatigue testing [ND/D] to demonstrate the fatigue resistance of the hose to bending cycles A minimum of 400 000 cycles shall be carried out
Tests 17 and 18 above could be combined into one test
Factory acceptance tests
General
All listed tests are non-destructive The results of these tests shall be recorded in a written report.
All hoses
1) Ambient pressure leak test including approved drying procedure
Measurements to include pressure, ambient temperature and humidity Temporary and permanent elongation checks)
2) Electrical testing (for electrical continuity)
3) Dimensional checks (length, diameter (OD and ID) connectors etc.)
5) Inspection of marking and identification plate (marking requirements defined elsewhere).
FAT tests on one hose per order
To be mutually discussed and agreed between owner and vendor.
System testing
The system vendor, which may or may not be the hose vendor, is responsible for conducting tests to verify the performance of the hose within the overall system These testing requirements are outlined in the EN 1474-3 standard.
General
The quality system must adhere to EN ISO 9000 and EN ISO 9001 standards A competent certifying authority will conduct validation of all design and testing through comprehensive review and/or type approval.
Material selection
The selection of materials and equipment for cryogenic hoses must be clearly defined and validated by a qualified certifying authority through material specification data sheets These sheets should comprehensively detail each component layer, its specific function, approved suppliers, and the levels of quality control.
The material specification data sheet shall also include auxiliary materials e.g nuts, bolts, seals, welding materials.
Marking
Each end fitting shall bear a permanent identification, showing, as a minimum:
internal diameter of the hose;
the hose shall be permanently marked with the date of the proof pressure testing, its specified MAWP and its maximum and minimum service temperature;
NOTE This is in accordance with IMO IGC Code (complete reference is given in Bibliography)
overall weight of the hose and end fittings assembly;
date of factory acceptance test;
certifying authorities stamp (if applicable).
Manufacturing
Type approval must encompass a comprehensive overview of the manufacturing process, detailing the manufacturing equipment, welding procedures, assembly controls, and quality assurance/quality control interventions All these elements should be validated as part of the overall production process Additionally, a review will be conducted by the relevant certification authority, as mutually agreed upon by the owner and the vendor.
Documentation related to an approved certification process
As part of an approved quality system, the Vendor shall provide the following documents:
approved certification authority 3 rd party type qualification/certification;
As-built documentation
The as-built documentation shall include, as a minimum the following:
references to design specifications and drawings;
all non-conformances identified during manufacture, and repairs performed;
welding procedure specifications and qualifications;
NDE operator qualifications and NDE test records;
Operation manual
An operating manual must be created for the system, detailing all maintenance tasks, restrictions, and emergency procedures, including specified repair procedures from the vendor or owner At a minimum, the manual should encompass these essential elements.
weight per meter and weight of end fittings, accessories;
MAWP and test pressures, allowable vacuum if applicable;
design minimum and maximum temperatures;
design water depth if applicable;
handling, storage, winding/unwinding procedures;
reference for as-built documentation
If specified by the owner, a separate installation manual shall be supplied, and this shall document the installation procedures
This table gives data for the LNG hose assembly and whether it is relevant to EN 1474-2 and EN 1474-3
Owner’s technical contact: Enquiry date:
Conformance to Required response date:
Tolerance required on length ( ± mm):
Hose structural requirements (MBR, bend stiffness):
DESIGN LOAD CASES (1 year, maximum operational, normal disconnect/reconnect, emergency disconnect)
Weight requirements (kg/m) in air empty:
External protection requirements: Normal operation:
Service life (years): Specification of normal and abnormal load cases, including accidental loads, and definition of load combinations to be used in the design:
GENERAL FLOW RATE AND THERMAL
CALCULATIONS (liquid or vapour) Flow rate (m 3 /h):
Maximum Allowable Working Pressure (MPa):
Operating pressure (MPa): Required outlet pressure (MPa):
Vacuum conditions (MPa): Fluid heat capacity (kJ/kg/°C):
AIR TEMPERATURES Water depth (m): Minimum temperature (°C):
Minimum tidal variation (m): Maximum temperature (°C):
Maximum tidal variation (m) Minimum storage/transport/installation temperature (°C):
Maximum storage/transport/installation temperature (°C):
Marine growth to be considered?
Ice effects to be considered?
If yes, attach details Sunlight exposure?
Yes No Current data attached?
Attached current data should be given as a function of water depth, direction, and return period
Wave data attached? Wind data attached?
Attached wave data must include significant wave height, maximum wave height, equivalent periods, spreading functions, and scatter diagrams, all presented as a function of direction and return period Additionally, for irregular seas, it is essential to specify the wave spectrum data.
Attached wind data should be given in terms of maximum 3 s, 1 min, 10 min, and 1 h wind speeds, as a function of direction, height above water level, and return period
Electrical continuity required? Leak monitoring system?
If yes, give details of requirements
Thermal insulation required? Connector type (flange, pipe):
Impact resistance to accidental loads
Required hose attachments (bend restrictors, clamps):
Yes No Attach drawings of all items
INTERFERENCE Interference/clashing check required?
Yes No VESSEL MOTION DATA
Attach details of all possible interface areas, such as; other hoses, mooring lines, fenders etc
Vessel or manifold motion data attached?
The attached motion data must be detailed according to the relevant loading conditions, including a general layout drawing that indicates the vessel's heading, the North point, and the mooring lines.
Static and dynamic offset for all conditions
First- and second-order motions, in terms of heave, surge, sway, yaw, roll and pitch
Motion phase data and specification
Materials required in addition to EN 1474-2 ?
Manufacturing required in addition to EN 1474-2 ?
FAT required in addition to EN 1474-2 ?
Markings required in addition to EN 1474-2 ?
Additional national authority/government regulations?
General requirements in addition to EN 1474-2 ? Yes No
DELIVERY, INSTALLATION, AND MAINTENANCE REQUIREMENTS
Shipping, packing and storage requirements:
Prototype and factory acceptance tests for LNG hose assemblies
PROTOTYPE AND FACTORY ACCEPTANCE TESTS FOR LNG HOSE ASSEMBLIES for full details of all tests refer to EN 1474-2:2008, Clause 6
6.3 Composite Corrugated metal hose DESIGNATION
Pressure cycle tests (ambient) 200 x Y Y 4 N/A N/A IMO/IGC code
Cryogenic fluid compatibility Y Y N N Lab test
Ambient pressure and leak test Y Y 1 Y Y
Cryogenic pressure and leak test Y Y 2 N N
Cyclic temp and pressure testing Y Y 17 N/A N/A
PROTOTYPE AND FACTORY ACCEPTANCE TESTS FOR LNG HOSE ASSEMBLIES for full details of all tests refer to EN 1474-2:2008, Clause 6
6.3 Composite Corrugated metal hose DESIGNATION
Dimensional checks (length, ID, OD) Y Y Y Y
Items marked as N can be requested by the owner, but are not standard FATs
Surge pressure considerations for LNG hoses
The Maximum Allowable Working Pressure (MAWP) is a critical parameter used by terminals to establish the pressure capabilities of their cargo systems, encompassing pump shut-in pressure, static head, and safety valve relief settings While the MAWP does not account for dynamic surge pressures, it does consider nominal pressure variations during cargo transfer operations As per the IMO IGC Code, the MAWP must be at least 10 bar gauge.
During the Factory Acceptance Test, the hose must undergo pressure testing to ensure its structural integrity under internal pressure, with the test pressure set between 1.5 times the Maximum Allowable Working Pressure (MAWP) and no more than 40% of its bursting pressure.
The proof pressure, calculated as five times the Maximum Allowable Working Pressure (MAWP), accounts for the extra pressure generated by surge events, such as when cargo fluid is abruptly halted due to the rapid closure of a marine vessel or terminal valve This surge pressure adds to the existing pressure within the cargo system and varies based on the specific cargo transfer system in use, necessitating a thorough assessment for each marine terminal's cargo transfer operations.
Hydraulic hammer actions occur due to excessive overpressure caused by the abrupt stopping of a pump or the closure of a valve To accurately assess these actions, a method validated through LNG experimentation should be employed For initial calculations, simplified formulas can be utilized to determine the overpressure values resulting from valve closure, expressed as LNG column height, denoted as \$D_h : t L\$.
L length of pipeline in m; t closing time of the valve in s; v shock wave speed, v = 1 500 ms-1 for LNG;
Dh height of the LNG column equivalent to the over pressure in m;
Vo flowing velocity of LNG before hydraulic hammer in ms-1; g acceleration due to gravity in ms-2
The shock wave velocity is dependent also on the characteristics of the pipe
Higher pipe elasticity leads to a slower shock wave A shock wave speed of \$v = 900 \, \text{ms}^{-1}\$ for LNG in hoses is deemed optimal, yielding more conservative closing time values.
The hose length for offshore application is expected not to exceed 50 m The term t L
>2v then becomes t > 0,11 s The closure time of the emergency release coupling valve should be more than 5 s and therefore clearly indicates the use of the second equation
The velocity Vo in the loading hoses will not exceed 12 ms-1 according to this European Standard
With a maximum LNG density of 480 kg/m³, this translates into a surge pressure of 1,17 bar
When loading an LNG carrier, the pump head typically remains below 120 m, while unloading can reach pump heads of up to 165 m Notably, the pump curve can increase by 20% at zero flow, resulting in a maximum head of 198 m (or 9.50 bar).
Triggering the closure of the emergency release coupling valve should is expected to be a rare effect The normal sequence prior to this event will be:
• closing of the ESD valves (closure time is in the range of 20 s to 30 s, therefore resulting surge pressure will be much lower than calculated above);
• activation of the emergency release coupling
The emergency release coupling will only activate under full flow conditions if both the pumps fail to shut down and the ESD valves fail to close In such a scenario, the pump's zero flow pressure and surge pressure could accumulate during LNG unloading, potentially reaching a total pressure of 10.67 bar, which remains safely below the proof pressure of 15 bar for a hose with a maximum allowable working pressure (MAWP) of 10 bar.
Surge pressure can occasionally exceed the Maximum Allowable Working Pressure (MAWP) of a hose, reaching up to the proof pressure, which is 1.5 times the MAWP This is justified by the rare nature of surge pressure occurrences and the specified minimum burst pressure of five times the MAWP The frequency and duration of such surge events should be mutually agreed upon by the owner and the vendor.
[1] Accident Prevention (IP no 4): the Use of Hoses and Hard Arms on Marine Terminals Handling Liquefied Gases – SIGTTO
[2] Flexible Hoses of Metallic Material No 2.9 Type Approval Programme 5-791.80 – DNV
[3] Flexible Hoses of Non-Metallic Material No 2.9 Type Approval Programme 5-791.70 – DNV
[4] International Code for the Construction and Equipment of Ships Carrying Liquefied Gases in Bulk – IGC Code and Amendments – IMO
[5] Liquefied Gases Handling Principles on Ships and in terminals –SIGTTO
[6] Safety Guide for Terminals Handling Liquefied Gases in Bulk – OCIMF
[7] Ship to ship transfer of liquefied gases – SIGTTO
[8] EN 1473:2007, Installation and equipment for liquefied natural gas — Design of onshore installations
[9] EN 12434, Cryogenic vessels — Cryogenic flexible hoses
The EN 13766:2003 standard specifies the requirements for thermoplastic multi-layer (non-vulcanized) hoses and hose assemblies used in the transfer of liquefied petroleum gas (LPG) and liquefied natural gas (LNG) This standard is divided into two classes, catering to both onshore and offshore applications, with hose diameters ranging from DN 25 to 250 mm and working pressures between 10.5 bar and 25 bar.
[11] EN ISO 6708, Pipeworks and Components — Definition and selection of DN (nominal size) (ISO
[12] EN ISO 10380, Corrugated metal hoses and hoses assemblies (ISO 10380:2003)
[13] EN ISO 10806, Pipework — Fittings for corrugated metal hoses (ISO 10806:2003)
[14] ISO 21028-1, Cryogenic vessels — Toughness requirements for materials at cryogenic temperature — Part 1: Temperatures below –80 °C
[15] ISO 23208, Cryogenic vessels — Cleanliness for cryogenic service