8.1.1 Where the cargo transfer system between two units is fitted with a
linked emergency shut-down (ESD) system, see
Pt 7, Ch 1, 7.4 Linked ESD systems, and an emergency release system (ERS), ensuring
the coordinated operation of both ESD and ERS functions and the prevention of
overpressure in the transfer system, the requirements of this Section are to be
complied with. The design of ERS systems is to comply with the requirements of
EN1474-1 and 3, Installation and equipment for liquefied natural gas – Design and
testing of marine transfer systems or alternative relevant International or
National Standard and this sub-Section.
8.1.2 The function of the ERS protects the offloading configurations by
disconnecting them, should the units drift out of their operating envelope.
NOTES
- Examples of offloading configurations are the following:
- Marine transfer arms systems.
- Rigid supported hose systems.
- Aerial flexible hoses.
- Floating flexible hoses.
- Operating envelope is the maximum spatial area in which the
presentation flange of an offloading configuration system can operate
safely.
8.1.3 Means are to be provided to activate the Emergency Release System (ERS)
manually from the central control station and locally, where the cargo transfer
process is monitored or visually observed. Should the marine transfer arm/hose
extend outside its operational envelope, this is to be detected by sensors, leading
to automatic activation of the emergency release system (ERS).
8.1.4 Manual ERS activation points are to be protected against inadvertent
operation.
8.1.5 In an emergency, when the offloading configuration requires to be
disconnected, this should occur as a two-stage process:
The design of the systems should be such that the second stage cannot be
activated unless the functions of the first stage have commenced.
8.1.6 The ERS activation sequence is as follows:
- simultaneous closure of the interlocking ERS isolating
valves;
- activation of the Emergency Release Coupler (ERC);
- disconnection of the arms/hoses;
- retraction to safe position.
Each stage in the sequence must be complete before the next
commences.
8.1.7 ERS activation procedures are to be clearly posted at the ERS operating
location(s).
8.1.8 The emergency release system (ERS) is to be independent and separate from
the linked ESD system. Although the ERS system is to be independent from the ESD
system, it may share a common power source, provided that a failure in either system
does not render the other system inoperable, e.g. failure in hydraulic or pneumatic
control lines.
8.1.9 All relevant initiation signals at either end of the link shall be
processed and transmitted through an established ERS link, as a single ERS signal
and not as individual signals.
8.1.10 The overall design of the offloading configuration, ESD and ERS systems
should consider offloading environmental conditions and locations. The design of
this system shall take into account possible ice build-up.
8.1.11 The ERS operating system shall be designed to retain sufficient stored
energy to release all transfer arms/hoses in the event of unit blackout and the
non-availability of provided utilities. Loss of power should not result in automatic
activation of the ERS.
8.1.12 An uninterruptible power supply is to be provided to supply power to the
logic and control systems.
8.1.13 Electrical, electronic and programmable components which are part of the
safety system shall comply with IEC 61508, Functional safety of
electrical/electronic/programmable electronic safety related systems.
8.1.14 Access to the system is to be restricted so that software may only be
modified by suitably authorised personnel.