Goro Nickel Mine Ocean Outfall

The Goro Nickel Mine subsea outfall upgrade involved replacing a 3.6km section of 800mm diameter HDPE ballasted pipeline. The pipeline serviced Vale’s Goro Nickel Mine and needed to be installed within a narrow offshore corridor, requiring tight lateral control during placement.

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The installation was completed from the surface in 10 pre-assembled pipe segments, with minimal dive support. An ROV was used to guide the precise placement of the pipeline, reducing reliance on diver intervention and improving control during offshore installation.

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Key Project Elements

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Pipeline Design and Installation

• Detailed design of the 800mm diameter HDPE subsea outfall pipeline
• Replacement of a 3.6km section of ballasted pipeline
• Installation in 10 pre-assembled segments
• Surface-based installation with minimal dive support
• ROV-guided placement within a constrained offshore corridor

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Temporary Works and Barge Systems

• Guide frame fixed to the side of the barge to provide lateral control of the floating pipe and ballast blocks
• Barge-mounted davits to lift the end of the pipe string
• Davit system used to hold the pipe elevated while connections between pipe strings were made
• Guide barge arrangement designed to achieve lateral tolerances beyond those normally required for similar installations

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Sinking Methodology

• Controlled sinking by introducing water into one end of the pipeline
• Air vented from the opposite end to manage the sinking sequence
• Pipeline overpressure of 4.5 bar released as water was introduced
• Detailed installation procedure developed to guide the contractor through the sinking and connection process

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Structural and Strain Analysis

• Extensive analysis of pipeline strain during sinking
• Checks undertaken to confirm allowable pipe stresses were not exceeded during installation
• Installation sequencing refined to manage pipe behaviour, ballast effects and connection loads

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This gives the profile more engineering weight. It shows the real complexity: long HDPE pipeline, tight corridor, barge guide system, davits, controlled flooding, overpressure release, strain checks and ROV positioning.