FEED for Elimination of Stray Voltages In Dukhan Plant, Qatar

QP Gas Recycling (RG) Plant processing facility in Dukhan recovers the condensate and NGL content of the gas cap of the Arab-D reservoir.

Cables for various signals such as command, status and control purposes are installed between LV switchboards in sub station-G and LER-G in RG plant at Dukhan. These cables are unarmoured and run over cable trays and ladders in open atmosphere in the cable cellar below the floor slab of sub station-G and LER-G.

Stray voltages up to 150V DC have been detected in the control, status and command cables that might be the cause of frequent malfunctioning of command, status and control signals. In the present case the stray voltage phenomenon is appearing at random and typically it affects one set of motor at a time. The effect of stray voltage is quite random and unpredictable. It can cause the shutdown of AGRU, ERU and Injection booster compressors, if it affects a large number of motors.

The objective of this project is to avoid frequent malfunctioning of command, status and control signals, which may lead to unplanned plant shut downs caused by the stray voltages.

The modification works are as follows:

• Replacement of all existing command, status, control cables with EMI shielding cables.
• New / Replacement / Reinstallation of cable trays and resolving installation issues such as bonding and grounding.
• Sorting and rerouting installed cabling to achieve the correct separation distance thus preventing stray voltages.

Services provided

• Surveys and site investigations of existing facilities associated with the services:
  • Survey existing facilities, including underground, with respect to all disciplines as appropriate.
  • Identify and verify all interfaces, tie-in points and interlocks between existing and new facilities under the subject of the SERVICES.
  • Identify preliminary locations for both possible temporary and likely permanent works
  • Verify availability and adequacy of all required utilities and services.
  • Topographical survey and underground services survey and prepare reports and drawings.
  • Identify and retrieve existing geotechnical survey reports for the area to establish foundation design criteria.

• Preparation of Design Basis Memorandum, including:
  • Design Basis,
  • Proposed variation to specifications and standards
  • Outline of operating and control philosophy
  • Constraints & Areas of concerns
  • Constructability, including shutdown requirements
  • Corrosion prevention and material selection
  • Utilities requirements
  • Safety and loss prevention philosophies, e.g. fire detection protection and alarm for all new equipment including power isolation in the event of fire or any kind of emergency

• Preparation of EPIC Tender Package:
  • Prepare EPIC Scope of Work (SOW) document based on the SOW template for all disciplines.
  • Prepare a consolidated, itemized Bill of Quantities for the EPIC work.
  • Prepare a consolidated Level II Planning Package commencing from issue of EPIC Tender until EPIC Close-Out.
  • Prepare a consolidated Cost Estimate for EPIC Scope of Work,
  • Prepare Contract Execution Plan.
  • Prepare Procurement Lists.
  • Compile Appendices A (Scope of Work), B (Schedule of Prices), F (Drawings) and H (Contract Execution Plan).
• Complete Front-End Engineering Design (Civil/Structural, Electrical, l&C, Loss Prevention and Environment)
• Design Studies.

Client

Qatar Petroleum (QP), Qatar