13.1. General
13.1.1 The requirements specified are the minimum requirements of the Purchaser but the Vendor shall be ultimately responsible for all aspects of the equipment supplied regardless of source and shall be responsible for ensuring compliance with all relevant local and national codes and regulations, etc.
13.1.2 The specification complements the equipment data sheets in which the operating conditions and other requirements are listed in detail. In case of conflict the order of priority shall be:
1) Data sheets
2) The Purchaser’s technical specification including Section 13, Design specification 3) The piping and instrumentation diagrams (P&ID's)
4) Other referenced specifications, codes and standards including OCIMF 3rd and/or BS EN 1474
Any conflict in the documents listed above should be reported by the Vendor and should be agreed with Purchaser in writing.
13.1.3 Definition of terms and abbreviations used in this specification related with arms shall be in accordance with OCIMF, 3rd and/or BS EN 1474.
13.1.4 All other requirements specifically not mentioned in this specification shall be in accordance with OCIMF, 3rd and/or BS EN 1474.
13.1.5 The term "Loading Arms or Unloading Arms", as used in this specification, shall mean all arms included in this specification.
13.1.6 All loading arms shall be self-supported marine loading arms with articulated swivel joints inclusive of, where specified, quick connect/disconnect couplings, power system, operating controls, range control system, purge system, emergency release system, jacks and other related accessories required by this specification.
13.1.7 The design pressure as specified in the data sheet is the maximum pressure in the loading arm taking into account occurrence of surge due to quick closing valves be it in the shore piping or in the ship's piping.
13.2. Design and construction
The unloading arms design shall be suitable for unloading LNG liquid from LNG tankers in the capacity range between 123,000 and 270,000 m3 of LNG. Refer to Section 3.4 and the Data Sheets for details of LNG Tankers.
13.2.1 Each loading arm shall be of the pantograph cable type, fitted with self levelling triple swivel assembly and equipped with an emergency release system and a hydraulically powered connect/disconnect coupling.
The structural part of the cryogenic arms shall be independent from the one of the product carrying pipe to allow for thermal shrinkage
The Loading Arms shall be fitted with inboard and outboard arms counterbalanced empty in all positions.
13.2.2 The Loading Arms shall be working at no more than 80% of their safe working range anywhere within the working area specified on the data sheets.
13.2.3 The design of the unloading arm emergency shutoff and release system shall be designed to a high level of reliability. The Vendor shall demonstrate by fault free analysis that the fraction dead-time of the overall loading arm shutdown system shall not exceed 0.001.
13.2.4 The Loading Arms shall be hydraulically operated, slewing/inboard/outboard, dock mounted with articulated ball or roller bearing swivel joints.
13.2.5 The design of each arm is to be such that there is no clash with piping or adjacent structures.
13.2.6 In the stored position no part of the arms shall extend beyond the jetty face.
13.2.7 The range of arm movements shall allow the triple swivel assembly to be positioned on the jetty for maintenance using dummy manifold. Vendor shall indicate the intended location.
13.2.8 The arms will be purged with nitrogen. Vendor shall provide a valve connection with purge lines and flexible hoses to a coupling at the shore end of the loading arm.
13.2.9 Vendor shall supply and guarantee the pressure drop versus flow rate data for all the arms.
13.2.10 All unloading arms are to be designed to permit reverse flow. This will allow LNG transfer from the terminal to a ship at a reduced flow rate via the liquid arms and vapour from/to a ship to pass the terminal vapour recovery system via the vapour arm.
13.2.11 Description of the different components of the loading arm follows in other sections of this specification.
13.2.12 The design and construction of the Loading Arms shall generally be in accordance with the specifications listed in Section 4.
13.3. Materials
13.3.1 Materials for construction proposed by vendor shall be suitable for the operating and design conditions specified in the Data Sheets and Specifications, Codes and Standards defined in Section 4.
13.3.2 For welding purpose the carbon contents of the carbon and carbon/manganese steels for structural/mechanical loading arm components shall not be higher than 0.23% unless otherwise specified; the carbon equivalent according to:
15 5
6
Ni Cu V Mo Cr C Mn
Ceq shall not be higher than 0.45
13.3.3 Swivel joints and fluid carrying parts of couplings shall be constructed of materials which do not cause galvanic action with the pipe used in the arm.
13.4. Swivel joints
13.4.1 All swivels and structural bearings, where lubrication is required, shall be capable of being lubricated without dismantling and shall be designed to prevent over-pressurization from lubrication.
Cryogenic swivel joints shall be equipped with connections to permit purging with nitrogen.
During operation of the arms the cryogenic product swivel joints shall be pressurised with nitrogen.
13.4.2 Except for the outboard joint (triple) swivel, all swivel joint assemblies shall have devices to permit re-packing without dismantling major sections of arms.
13.4.3 The swivel joints shall have ball (minimum two races) or roller bearings. The sealing system of cryogenic swivel joint shall have at least two main seals and one external seal.
13.4.4 The outboard joint (triple) swivel, including the emergency system, hydraulic Quick Connect Disconnect Coupling (QCDC) etc., shall be balanced so that the outboard flange remains in the vertical plane for all arm attitudes.
13.4.5 All swivels in the loading arm shall be designed so that external water cannot penetrate and freeze in the joints between rotating parts of the swivel.
13.4.6 Swivels shall permit temporary vacuum conditions and reseat properly afterwards.
13.4.7 All swivel joint design shall be such that non-Destructive Examination (NDE) of the ball races is possible. Hardness of ball or roller raceways must be over 40HRc.
13.4.8 Heat treatment or surface treatment of the ball races is not acceptable.
13.5. Quick-connect/disconnect cargo coupling (QCDC)
13.5.1 A hydraulically operated Quick Connect/Disconnect Cargo Coupling shall be provided for each arm to facilitate the loading arm connect/disconnect operations.
13.5.2 Aligning and centering devices shall be furnished for each diameter of flanges to which the coupling must connect.
13.5.3 Vendor to provide arm connection flange as specified in the data sheet.
13.5.4 Lubrication of all moving parts shall be possible without dismantling the coupling.
13.5.5 The coupler mechanism shall ensure that the coupling clamps operate simultaneously and evenly distributed forces are applied to the ships manifold flange during the connection and disconnection operation, thus avoiding overstressing of any part of the flange. This shall be achieved by means of spring support on each hook assembly.
13.5.6 The coupler shall incorporate an overcenter mechanical lock. Couplers relying on friction locks such as cams for primary or secondary locks will not be acceptable.
13.5.7 A single hydraulic double acting cylinder shall operate all the coupler clamps.
13.5.8 The hydraulic cylinder and primary moving parts of the coupler shall be insulated from the fluid carrying body so as to avoid icing of these components.
13.5.9 The coupler shall be capable of releasing from the ships manifold flange under maximum unbalanced loads induced by the loading arm and when clamp tips are covered with 25mm solid ice.
13.5.10 The coupler shall be equipped with a blanking plate designed for an internal nitrogen gas pressure of 0.7MPa.g. The blanking plate shall remain attached to the coupler when the coupler is opened accidentally. A suitable lifting davit shall be fitted to the loading arm to support the blanking plate when removed from the coupler.
13.5.11 The coupler design shall include for external centering guides which align on the outside diameter of the ships manifold flange.
13.5.12 It shall be possible to manually disconnect the coupler in the event of electric/hydraulic power failure of the loading arm power pack by means of a portable hand pump.
13.5.13 The strength of coupler shall be based on the requirement of OCIMF.
13.5.14 The coupler shall be designed in order that the interface connection is leak free during full cargo transfer and during cool-down of the loading arm.
13.5.15 As the quick connect/disconnect coupler is utilized in combination with the double ball valve/emergency release coupler then it shall be supplied with the device which disconnect automatically the hydraulic lines to the coupler following an emergency release. There shall be no leakage of hydraulic oil on release.
13.6. Emergency release system (ERS)
13.6.1 The ERS shall be initiated in the following ways:
Automatically : by over-extension angle signals (via proximity switches)
Manually : by push-buttons at the control station and other defined shore location under healthy power condition.
Manually : during total power failure by pulling knob/lever at ERS solenoid. No signal to logic will then be given.
13.6.2 The entire ERS shall be hydraulically operated with separate solenoid valves for the
emergency release coupling and operation of ball valves, unless the ball valves and ERC are activated by one cylinder.
13.6.3 The two ball valves shall be mechanically interlocked to guarantee simultaneous closure. The interlocking device shall easily disconnect when the arm is uncoupled at emergency release conditions.
13.6.4 Facilities shall be provided, either hydraulic or manual, for re-opening of the valves after emergency closure. Such facilities, when hydraulically operated, shall be designed as to allow opening of the valves only after the respective ERS components have been re-connected.
13.6.5 Closure time of the ball valves shall lie in the range of 3-40 seconds and be adjustable with tamper-proof flow regulators in the hydraulic system for each valve.
13.6.6 The response time of the electric/hydraulic circuit between initiation of an ESD and the start of the ERS valves closure shall be less than 1 second.
13.6.7 The control of the ERS shall guarantee ball valve closure prior to emergency release. The emergency release coupling shall have been disconnected automatically within 2 seconds maximum upon completion of valve closure, during ESD-2. (Refer to Section 13.11.7.)
13.6.8 The emergency coupling shall easily disconnect at the minimum design temperature (frost) and maximum forces exerted by the ship on the outboard arm.
13.6.9 The arrangement of the ERS assembly near the outboard end of the swivel shall be such that parts of the ERS assembly remaining on board of the ship after emergency release will not fall on ship's deck or manifold service platform.
13.6.10 The hydraulic cylinder operating the emergency release coupling shall be of the double acting type. Independent operation of double ball valves and emergency release coupler shall be provided by means of this separable double acting hydraulic actuator.
13.6.11 The emergency release coupler shall be a fully spring energized design to ensure
disconnection with a solid ice build up of 25mm minimum around the clamps of the emergency release coupler. The release shall be possible with or without full operating pressure and maximum external design forces.
13.6.12 The emergency release coupler shall incorporate separate clamps to suitable. The clamps shall not fully enclose the flanges.
13.6.13 The emergency release coupler shall incorporate an overcenter mechanical lock. Devices that require tightening of nuts or equivalent item are not acceptable.
13.6.14 The strength of ERS shall be based on the requirements of OCIMF.
13.6.15 The operation of double ball valves & emergency release coupler shall be hydraulically interlocked to prevent disconnection of the emergency release coupler before the ball valves are fully closed. The interlock valve shall meet in full the OCIMF specification.
13.6.16 It shall be possible to fully test the hydraulics of the emergency release system including the actuators without disconnection of the emergency release coupler or dismounting of hydraulic actuators.
13.6.17 The double ball valves shall be provided with an alignment/lifting and reassembly bolting system to assist in the reassembly of the equipment following an emergency release.
13.6.18 Fire Safe Testing of ERS components
1) The ERS valves and components located around the triple swivel joints such as flexible hoses, cylinders, etc. shall be fireproof so that they remain fully operable when exposed to fire, and shall comply with the requirements of ISO 10497.
2) Vendor shall submit full details and specification of recommended fire proofing with his bid.
13.6.19 At the swivel between the ball valve and the presentation flange a facility shall be provided to keep the ship side ball valve in an upright position following an emergency decoupling.
However, sufficient rotation freedom shall be given to align the loading arm presentation flange and the ship's manifold flange to allow for ships motion.
The design of the swivel shall absorb the shock load on the ships manifolds due to the rotation of the bottom part of the ERS unit after a disconnection of the ERS.
13.7. Accessories 13.7.1 Storm locks
Storm locks shall be provided for all loading arms designed for the worst wind conditions. The locking mechanism shall be mechanical for inboard arm, mechanical or hydraulic for outboard arm. Detail shall be as per OCIMF, 3rd, 1999.
When the arm parking lock is not properly engaged a light shall flash at the control panel.
13.7.2 Support jacks
Permanently attached adjustable jack, with two legs, shall be provided for all loading arms to reduce the stress on tanker manifolds.
13.7.3 Stray current protectors
1) An insulating flange or an integral joint shall be inserted near the triple swivel assembly of the arms to electrically isolate the ship from the loading arms.
2) The insulating resistance and other details shall be in accordance with OCIMF, 3rd, 1999.
3) The insulation flange/joint shall be designed to a strength safety factor of at least two.
13.7.4 Dummy manifold
Vendor shall provide movable cradle type dummy manifold skid. It shall be equipped with swing casters and retractable feet of copper alloy. Support jacks of triple assembly shall be able to be rested on the cradle skid. Triple assembly shall be fixed by dummy flange and turnbuckles on the cradle skid. All screws, turnbuckles and connecting hardware shall be stainless steel.
13.7.5 Spotting line indicator
In front of each loading arm or bank of loading arms a stainless steel instruction plate indicating the spotting centre line shall be provided by Vendor on the jetty head.
13.8. Hydraulic power system
13.8.1 The hydraulic system shall be designed and sized in accordance with Section 9.1, OCIMF, 3rd with following additional requirement:
1) Following ERS operation, the released arms shall be retracted inside berthing line 13.8.2 Arm manoeuvring shall be possible in two operating speed modes. The “Fast Speed” shall be
0.15m/s, and the ”Slow Speed“ shall be half the “Fast Speed”.
13.8.3 Separate flow control valves shall be provided to control:
- “Fast" operating speed - “Slow" operating speed
- Return speed after ERS disconnection
13.8.4 Each hydraulic circuit, or section which can be isolated, shall have relief valves of sufficient size to protect the loading arms, including the hydraulic system, from damage during normal operation and emergency release or due to operator error, malfunctioning, and hydraulic or electric power failure.
13.8.5 Hydraulically powered arms shall have an independent flow control valve installed in each cylinder line, each of which shall have a lockable tamperproof cover.
13.8.6 Adequate main line pressure protection shall be provided.
13.8.7 Pressure gauges with surge dampeners shall be provided in circuits having different pressures.
13.8.8 Hydraulic power pack
1) A 25 micron filter with replaceable cartridge shall be provided in the discharge of the pump and in the return line to the reservoir. Strainers capable of removing particles over 150 microns shall be installed in the suction line to the pump.
2) The power pack shall be supplied with duplicate pump sets. Each pump shall be supplied complete with a motor. The pump sets shall operate as 1 duty/1 standby.
3) To avoid moisture entering the hydraulic circuit the hydraulic reservoir shall be provided with a diaphragm to accommodate differing oil levels without allowing the ingress of air.
4) Hydraulics power pack pumps shall be designed and constructed for a minimum service life of 50,000 hours.
13.8.9 Hydraulic piping
1) Hydraulic lines, including tube and fittings, shall be 316 stainless steel. Minimum bore shall be 10 mm. Suitable flexible hose may be used as required to provide articulation or electrical insulation. Hoses shall be of smooth bore. Oil reservoirs shall be kept to a minimum to reduce the number of places of potential leaks.
2) The hydraulic piping system shall be assembled by means of compression joints.
Welding or threaded joint of pipes will not be allowed in the hydraulic system.
3) The hydraulic tubing shall be clamped and fitted with synthetic sleeves avoiding SS/CS contact.
13.8.10 Accumulators
1) For each loading arm an accumulator shall be provided to operate the ERS and QCDC, and shall be located as close as practical to the ball valves and coupling. This
accumulator shall be floating on the system and the hold up time of the pressure required to operate the ERS shall be at least 3 hours, when both AC + DC power failure occur.
2) A separate “manoeuvring" accumulator shall be provided to manoeuvre all arms back to stored position during an AC + DC power failure under all operating conditions. The retention time of pressure required to perform above activities shall be at least 3 hours.
13.8.11 For manoeuvring of the arms cylinders with double rod shall be supplied. Cylinder rod shall be hard chromized stainless steel rods.
13.8.12 The hydraulic directional valves shall be manually operable as well as solenoid operable.
13.8.13 For flushing and venting purposes the hydraulic circuit shall be provided with sufficient drains, vents and temporary by-passes.
13.8.14 To avoid ingress of air in hydraulic circuit, which will affect the response time of the ERS, a pressure control valve shall be installed in the return line to the tank in order to keep the system at all times pressurised to a minimum pressure of 0.3 MPa.g.
13.9. Operating control and emergency system
13.9.1 The control system for the hydraulic manoeuvring operations of the arm may be to manufacturer's standards, subject to Purchaser’s approval.
13.9.2 The control power for the loading arms shall be electro/hydraulic.
13.9.3 Controls for manoeuvring shall be through either the loading arms control panel located in the unloading arm control house (UACH) or through a pendant box (Local control) or through a wireless control (as a subsidiary). The control panel, pendant box and wireless pendant box shall not be operable at the same time. The selector switch for control panel or pendant box or wireless pendant box shall be located at the control panel.
13.9.4 The loading arms control panel (pressurized explosion-proof type) shall contain the following:
- Power to control on/off, key-locked.
- Hydraulic pump(s) on/off.
- Loading arm selector switch.
- Control panel/pendant selector switch.
- Loading arm manoeuvring controls, including QCDC activation.
- Slow/fast manoeuvring selector switch.
- ESD-1 (ESD 111.01) push button, fitted under a red flap-over cover. (I-4.1 Unloading shutdown)
- ESD-2 (ESD 111.06) push button, fitted under a red flap-over cover. (I-4.2 Marine shutdown)
- Reset ESD 1 & 2 (111.01 & 111.06) - Override selector, key locked.
- Reset ESD 1 & 2 (111.01 & 111.06) - Override selector, key locked.