From May to October 2015 Nautec worked with PT Hutama Karya (Persero) Indonesia to provide strengthening of corroded marine piles at Berthing Dolphin 1 (BD1), Berthing Dolphin 2 (BD2) and Mooring Dolphin 5 (MD5) at Ramba Jetty in order to extend the service life of the structures. The Port of Ramba is a crude export facility serving the Ramba Field in South Sumatera, Indonesia. The Jetty is utilised for handling over 360,000 bbls of oil and condensates to be transported to Storage Tanker Corridor at Selat Bangka. 

The Scope 

The scope of work provided by Nautec included:

  • Site Survey: Detail site Inspection and Soil Investigation
  • Engineering Analysis and design of piles to be strengthened
  • Setting up site camp for 6 months operation
  • Fabrication of clamp and mould
  • Cleaning of the piles with Ultra High Pressure water Jet and inspection using downhole camera for interior and exterior of piles
  • Clamp & Mould installation
  • Filling annulus and infill piles with Ultra High Performance Cementitious (UHPC) materials.

The Services

  • Inspection by the team suggested the berthing dolphin and mooring dolphin had experienced a dent near the splash zone and heavy corrosion of the marine piles.
  • Nautec carried out Marine Pile Strengthening services through infill grouting and clamp installation with annulus grouting method.
  • The team grouted 23 internal piles and 19 external piles for BD1, BD2 and MD5 with NaX® Q140 UHPC materials.
  • Nautec’s engineering team carried out detail clamp and mould design. The fabrication of the clamps and mould was performed by a steel fabricator in Jakarta, Indonesia under supervision of Nautec.

The Challenges

  • Most of the pile damage zones were found at MSL and under water at depths of 6 to 8m.
  • The Ramba Jetty is situated on the Dewas River in crocodile and other marine life infested waters, hence there are restrictions in place for deploying divers for underwater pile requalification work.
  • The Berthing dolphins were closely located near the oil loading jetty and hot work is strictly prohibited in such areas.

The Solutions

  • By designing clamps, which can be inserted down to -2m below riverbed without the assistance of divers, Nautec provided a diverless solution for the pile strengthening and structural subsea requalification work.
  • Strengthening of marine piles using grouting method is the most suitable solution for structural reinstatement of members and life span extension in this type of environment, as it does not require any hot work.

Client Benefit

  • NaX® Q140 UHPC grout, which has been developed and is manufactured by Nautec, is the ideal material for pile strengthening work and has been designed specifically for subsea strengthening and repair applications.
  • The UHPC materials are commonly used for infill of tubular joints and braces and unstressed grouted subsea clamps, where a very high compressive strength and E-modulus is needed.

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