BS/EN 1473-2016 pdf download.Installation and equipment for liquefied natural gas – Design of onshore installations.
The safety management during design and construction shall include design considerations and continuous reviews as outlined respectively in 45.2 and 4.5.3.
4.5.2 DesIgn
4.5.2.1 Common safety design features
4.5.2.1.1 Equipment and piping design for low temperature
Design pressures and temperatures of piping and equipment shall be selected to cover all anticipated operation and upset conditions. Suitable materials are listed in EN ISO 16903.
The stresses in pipe-work and equipment are affected by contraction/expansion phenomena due to temperature changes, the possibility of thermal shock and the method of insulation. Physical phenomena such as: liquid hammer, cavitation, flashing and two-phase flow shall be taken into consideration. The recommendations of Clause 9 are applicable. It is recommended that the main pipes are maintained In a cold condition, e.g. by circulating of LNG, line weathering.
4.5.2.1.2 Hazardous area classifications
All installations shall be subjected to a hazardous area analysis (see [121 and j13J). The terms of reference for such an analysis shall be laid down in accordance with EN 1127-1 and EN 60079-10-1 and EN 60079- 10-2.
The form and the extent of each zone may differ slightly depending on the national or professional code used but shall be in line with the methodology set forward in EN 60079-10-1 and EN 60079-10-2. Consideration shall be given to EN ISO 28460 for the jetty, particularly for the hazardous zones generated when the LNG ship is alongside.
The selection of equipment for use in particular locations shall be determined from the hazardous zone classification of these locations in accordance with EN 1127-1 and EN/IEC series (parts 0 to 25).
4.5.2.1.3 Internal over-pressure protection
Safety devices shall be provided to cover all internal over-pressure risks including those due to fire.
It is recommended that the discharges from conventional safety devices (safety valves, relief valves) are routed to the flare/vent system or the storage tank. Tank and vaporiser safety valve releases, if not routed to the flare/vent systems, should be routed to a safe location as defined by hazard assessment.
If low and high pressure releases are routed to the same system, the risk of excessive back pressure shall be avoided, If excessive back-pressure could occur in low pressure release system due to high pressure release, then separate flare/vent systems may be considered for high and low pressure releases.
— avoid the risk of failure of LNG, hydrocarbon refrigerant or gas filled pressure vessels and piping from external radiation.
Devices for depressurizing high pressure equipment shall allow the pressure of one or more item of equipment to be reduced quickly (see [3]). These gases shall be sent to the flare system which shall be capable of handling the low temperatures generated during depressurizing.
Isolation valves, activated from a control room or other remote location or automatically, shall be provided so that the unit can be isolated into several sub-systems and where it is required to isolate sensitive equipment. This will make it possible to depressurize only one part of the plant, while limiting the entry of hydrocarbons into a fire containing zone.
4.5.2.1.5 Safety control system
A safety control system (see Clause 14) shall be provided to identify, inform and react appropriately to hazardous events. The safety control system shall be independent of the process control system and identify the hazard and, were appropriate, automatically bring the plant to safe conditions.
4.5.2.1.6 Inherent safety
The inherent safety protection shall be provided to:
— contain LNG spills within the fence, and minimize the credible scenarios where there could be the risk that vapour clouds spread beyond the plant periphery fence;
— minimize the possibility of a fire in any one area of the plant spreading to another area;
— minimize damage in the immediate area of a fire by the use of separation distances, minimizing the hydrocarbon inventory feeding a possible fire (by segregating the plant in different lire-zones, by isolation valves).
The inherent safety is to be encouraged over the use of complex systems.
Inherent safety protection measures are detailed in 13.1.
4.5.2.1.7 Passive fire and embrittlement protection
The passive fire and embrittlement protection shall be provided to:
— protect equipment and main structural supports from localized fire incident minimizing escalation and endangerment of emergency response personnel;
— protect the main structural members from cold-splash brittle failure and resulting overall collapse. Passive protection measures are detailed in 13.2.BS/EN 1473-2016 pdf download.