5.1    General

The flare stack is considered “Essential Equipment” and needs to be in operation continuously to prevent shutdown of the compressor station. Hence, the flare stack is provided with a cold spare unit to allow normal maintenance during plant operation. The stand-by flare stack is out-of service during normal operation.

When requires maintenance of normal flare (scheduled activity), the cold stand-by flare stack will be activated and then switch over manually and then the normal flare stack will be isolated for the required maintenance activity.

The VENDOR shall supply, per each station, the following Tank, LP & HP flare units for normal operation and Tank, LP & HP flare units for cold stand-by in compliance to the reference documents in clause No. 4 to satisfy design and operational requirements under the conditions described in this specification

5.2    Equipment

The scope of supply shall include, but not be limited to the following, for each flare:

• Flare tip
• Flare stack (Tank, LP & HP) and guyed wires
• Purge reduction device (Velocity Type)
• 3 nos. of Pilots (vendor to certify if more number required) with dual type thermocouples, including conduit wiring (junction box, high temperature cable up to the VENDOR supplied LCP)
• Two (2) thermocouples per pilot shall be used.
• Burn back detector (thermocouple inside the flare tip)
• Package PLC system (common for both primary and secondary ignition system) and SIL-3 rated safety certified relays.
• High energy ignition system shall be provided for normal operation. Fault detection of ignition system to be provided. The primary high energy ignition system shall include:

 

1. Control panel (automatic / manual operation), shall be fully wired, including lamps, push buttons, timers, instrument air and pilot gas valve trains, ignition transformer, etc.
2. The sweet gas will be used as normal fuel gas for pilot, which will be taken from existing sweet gas header. The sweet gas for the pilot shall be provided by a 3” line.
3. Pilots with thermocouples (Duplex, type –K).
4. In the case of failure of Primary Ignition System, Continuous Spark Ignition system shall be provided as back-up system It shall be started automatically and necessary instruments to detect the failure shall be provided.

• The flare package shall be complete with all instrumentation and control system, as per Package Type 1B of package instrument specification.
• The flare package control system (that is provided as part of the local control panel skid) shall be microprocessor based PLC system which is common for high energy ignition system and continuous spark ignition system. The flare package control PLC shall be interfaced with the ICS system through redundant serial communication interfaces for remote monitoring, control and alarm purposes. The package system shall also be provided with SIL-3 rated safety relays for interfacing plant ESD system for initiating the remote shut down.
• The flare package PLC system provided as part of the LCP skid shall be configured in such that the following signals, as a minimum, are made available to the ICS system:
  1. Main flame ON indication
  2. Main ignition system fault
  3. Pilot gas pressure low
  4. Total pilot flame failure
  5. Back-up ignition failure
  6. Pilot flame ON (each pilot)

Further, the PLC system shall be configured to receive “remote manual ignition start command” from ICS system”.

1. Ignition Control Panel electrical components such as switching protection devices, thermostatically controlled space heaters with control switches.

1. In addition, residual earth fault protection shall be provided for the space heaters and lighting circuits.
2. Explosion proof IP 66 SS junction boxes as necessary.
3. HEI cable, TC cables for HEI, continuous spark ignition (CSI) shall be independent for each pilot
4. High energy ignition cables as a minimum Mineral Insulated Metal Sheathed (MIMS) from pilots at top of flare tip to first junction box.
5. Electrical cables, cable trays/ conduits, installation items etc. as necessary.
6. Electric winch with motor for retractable back-up ignitors. Rectractability package shall include wire harness, track assembly, electric winch & pulley assembly.
7. Riser fabricated in sections compatible with transport limitations,
8. Piping for pilot gas, flame conduit, etc with necessary supports,
9. Other utility piping and support brackets,
10. Access ladders and platform at flare tip base and at other elevations, as required.
11. Spare parts for pre-commissioning, in accordance with the requirements of of this specification,
12. Lifting lugs/ lifting devices for flare erection and for tip dismantling, lifting lugs for ignition panel skid, etc.
13. Template for flare stack base plate
14. Tailing lugs
15. Export packing and weather protection for shipping,
16. Saddles for shipping and site erection,
17. Stowage block, cradles, stiffeners and other special supplies for the handling, transport and erection of the equipment, if applicable,
18. Surface preparation and primary coating as required, on equipment and piping to be further heat insulated,
19. Final painting,
20. Pickling and passivation for stainless steel welded parts
21. Local nozzle load analysis as per ????,
22. Air Craft Warning Lights (ACWL), as per aviation regulations, including the supply of ACWL control panel and cabling for the package. Track & retractable equipment provided for back-up igniters may be used for ACWL retractability.
23. Top Davit with manual winch for retractability & electrical winch for tip retractability,
24. Radiation shield at top platform by providing ‘chequered plate’ (instead of grating) on top platform. This will facilitate in optimizing the resultant temperature profile along the length of flare stack,
25. Radiation shield shall be provided as per the VENDORs recommendation to cover the igniters’ pulleys and the igniter support wire rope (top portion).
26. Nameplates and tag plates,
27. Earthing bosses and earthing cables for the complete flare package. The package shall be provided with an earthing and bonding system. Each package shall be bonded with at least two (2) diagonally opposed points of connection to the plant earthing system using a standard earthing boss design,
28. Anchor bolts and nuts including anchor bolts for guy wired supports,
29. Guy-wired tensioners,
30. Supply of materials, Fabrication, All required Testing/NDE, Inspection, Rust prevention during transportation & site storage, Painting up to finish, Protection & seaworthy export packing, Inland transportation, Process performance & Mechanical guarantees for the equipment

 

5.3    Services and Documents

The VENDOR shall provide the following services and documents:

• Complete design of the flare and its associated equipment,
• Pressure drop calculation notes
• Noise level calculations
• Dispersion calculation for flame out conditions and flaring conditions
• Radiation isopleths for all operating cases
• Minimum purge rates (Nitrogen) to prevent air ingress
• Utilities consumption list: Nitrogen, Fuel gas for pilots (Sweet Gas), instrument air, electric power.
• P&ID showing clearly the VENDOR’s scope and the Battery Limits
• Electrical single line diagram, wiring and interconnection diagrams
• Technical data sheets for the Ignition Control panel, HV cables, Ignition transformers and LV power, control & lighting cables.
• Data sheets for instruments and control valves
• Cable routing details
• Data sheets for electric winch motor for retractable Back-up Ignitors
• Specification for all instruments, valves and control system
• Electrical wiring diagrams for ACWL control panel
• Electrical power rating and consumption details
• Logic Diagram
• I/O list
• Instrument Index
• Modbus mapping list
• All documents required for local authorities approval of equipment,
• Any other document requested in the Material Requisition,
• All tests, analysis and acceptance of materials, welding procedures, electrodes, rods and welder qualification for shop welds,
• Shop tests for the flare control panel,
• Flare package PLC communication interface test with ICS at flare package VENDOR’s works.
• Required services and coordination with Local Authorities for all necessary agreements, authorizations, certifications,
• Recommendation for extensive storage of equipment and materials,
• Instructions for erection and detailed welding specifications,
• Instructions for start-up, normal operation and shut down as well as those regarding prevention and suppression of failures, if any,
• Site Acceptance test (SAT) for flare package system in coordination with the ICS system vendor at site.
• Supervision for erection and assistance during start-up.
• Availability computations

5.4    Details of Battery Limits

The limits of supply are:

On flare stack:

• On flare riser: Flare gas inlet flange connection at riser bottom (in accordance with the applicable piping class) with the diameter given on the flare data sheet
• Pilot (Sweet Gas) lines for high energy ignition system, individual flanged connections at flare bottom

On Ignition control / high energy ignition panel:

• Fuel gas and Instrument air: at flanged connections at limit of panel
• Pilot lines: at flanged connections at limit of panel
• Electrical power connection: CONTRACTOR will provide single point power supply. Further distribution shall be done by VENDOR.
• CONTRACTOR will provide single point power supply to ACWL control panel. Further distribution shall be by VENDOR to ACWL, winch motor etc.

Instrumentation:

• Skid mounted package PLC – for interfacing the VENDOR supplied PLC with the ICS system through redundant serial communication interface.
• Skid mounted Package Panel – with SIL-3 rated relays for interfacing phase PLC with plant ESD system.

 

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