COMALCO MINING AND REFINING – MISSION RIVER BRIDGE

During the years 1997 to 2000, Pacific Marine Group has been involved with Comalco on what is believed to be Australia’s largest ever wet welding project and associated underwater inspection programme on the 1080m long Mission River Bridge at Weipa, North Queensland. Up to 20 dive- and support-crew are involved in the project, and up to 950 dives and 2000 in-water hours have been recorded per year. The initial project was mainly devoted to underwater welding repair and reinstatement of the bridge structure, resulting in a partnership with UK specialist underwater welding company “Hydroweld”. This allowed PMG access to the Hydroweld FS 3.2 Wet Welding Electrode, recognised throughout the world for its superior quality.

Later campaigns have also had a large component of underwater welding, but have also included associated inspection and construction specific tasks.

Inspection techniques used include:

	Cleaning, utilising hand tools, grit blasting and water-blasting
	Visual inspection
	Video inspection
	Still photography
	Magnetic particle inspection
	Alternating Current Field Measurement (ACFM)
	Cathodic Potential (CP) readings
	Ultrasonic thickness reading, using both hand-held digital read-out meter and “A” scan
	Detailed corrosion mapping of pile surfaces using the Microset Underwater Replica System

Construction tasks undertaken include:

	Installation of strengthening splints to piles and associated techniques including the use of cementitious and epoxy grouts
	Upgrading of CP system including replacement of existing anodes and installation of reference cells
	Use and fitting of Denso products to further protect piles

In 2001 and 2002 Pacific Marine Group again returned to Weipa to continue upgrading and replacement of CP system components. In 2004 Pacific Marine Group carried out a limited wharf pile inspection on Comalco’s freight transfer facility in Karumba.

During September 2004, Pacific Marine Group once again mobilised to Weipa to continue with underwater inspections and repairs on the Mission River Bridge. The works were completed mid November 2004, and involved a specialised 21 man crew including inspection divers, underwater welders, general divers, technicians, QA and Project Management staff.

CHEVRON NIUGINI / OIL SEARCH LIMITED – KUMUL TERMINAL OIL RIG

Pacific Marine Group has provided services to Chevron Niugini since the installation of the Kumul Terminal facility in 1992. The contracted work includes the provision of personnel and equipment to carry out all inspection and underwater maintenance work associated with this facility in Papua New Guinea. This contract includes a 24-hour on-call service for emergency activity as well as regular inspection and maintenance activity.

Pacific Marine Group carries out a yearly inspection of all submarine equipment including full inspection programs and all required remedial works. The poor visibility, strong tides and floating debris make this a challenging area in which to carry out the underwater activity.

Diving Depths at the site range from 10 – 50m, and surface decompression, through the use of a containerised decompression chamber, is generally utilised.

This facility consists of approximately 40km of 20 inch weight coated pipeline installed in the Kikori / Nakari River system and a further 45km of pipe leading to the platform. The pipeline finishes at the PLEM (Pipeline End Manifold) and SPM (Single Point Mooring) located 3km from the platform.

Typical tasks performed during the yearly inspection program include floating and sub-sea hose change outs, underwater welding, underwater grit blasting and magnetic particle inspection, ultrasonic thickness measurements, cathodic protection measurements, scour assessment, paint coating condition reports, marine growth assessments, chain link wear measurements. In addition to inspection activities, remedial works including single point mooring buoy underwater hull plate replacement utilising wet welding have been completed.

Another project completed at the site was the placing and filling of custom-built grout mattresses at the PLEM and pipeline support forms. This was done to rectify and to prevent further problems with scour, which was undermining and threatening the subject components. A total of eleven mattresses were placed and over 50m3 of grout pumped during the course of this project.

In 2003 Chevron Niugini sold all it’s PNG oil and gas interests to Oilsearch Limited, and Pacific Marine Group has continued to provide services to the new owner.

During the 2005 inspection, a major anomaly was discovered. One of the SPM mooring legs (mooring leg 1) was found to be broken. The 115mm steel wire rope had parted some time in the previous 12 months. Further inspection of the other legs revealed the steel wire rope for mooring leg 6 to have a number of broken wire strands towards the lower chain / wire interface.
As a result of these anomalies, a full wire replacement campaign for wires 1 and 6 was completed during the 2005 PIMP campaign.

Pacific Marine Group’s involvement in the replacement campaign was to provide diving services associated with the campaign.

A number of selected construction tasks carried out by Pacific Marine Group during the course of the programme included:

All diving services associated with the replacement of 115mm SPM wires 1 and 6 including:

	All underwater rigging tasks
	Chain angle surveys using various methods
	Assist on site surveyors with placement of various markers, buoys, transponders etc
	As built measurements and inspections
	Hydrographic survey and underwater magnetometer search works associated with recovery of buried chain 1
	Cathodic Protection surveys + sampling (water and seabed material)

BMA – INSPECTION DIVING SERVICES TO HAY POINT OFFSHORE LOADING FACILITY

Pacific Marine Group carries out underwater inspection campaigns, generally on a yearly rotation, on BMA’s steel piled offshore coal loading facility at Hay Point – 50km south of Mackay – Qld.

The overall condition of the piles, concrete caissons, cathodic protection system, scour mats and fender system is assessed and reported on. A range of non destructive inspection techniques are employed including Ultrasonic Thickness (UT) measurements (check steel pile thickness), Cathodic Protection (CP) measurements (check effectiveness of CP system) and Magnetic Particle Inspection (MPI) (check for node weld defects), as well as visual inspections including general visual and close visual inspections.

Anomalies are reported daily to client representatives, allowing mitigative measures to be completed ASAP.

Pacific Marine Group has completed numerous marine structure inspection campaigns including the following:

	Lucinda Bulk Sugar Offshore Facility
	Townsville Port berths
	Half Tide Tug Harbour
	Alcan Gove Offshore Facility
	Cape Flattery Silica Mine Offshore Facility
	Dalrymple Bay Offshore Facility
	Comalco - Mission River Bridge and Karumba loading wharf

CAPE FLATTERY SILICA MINE OFFSHORE LOADING WHARF PILE REPAIRS

During 2001, Pacific Marine Group completed a pile underwater repair program for Transfield, on Cape Flattery Silica Mines offshore loading wharf located at Cape Flattery, North Queensland. Cape Flattery is approximately 50km north of Cooktown, and is very isolated with no usable road access.

142 steel piles were pressure tested, with 437 holes found, and subsequently repaired. The holes were located by fitting a stainless steel socket to the top of all 142 piles comprising the contract. An air hose was then fitted to the socket, the pile pressurised, and any holes found were then easily identified by the air rushing out. Once holes were identified, a diver was sent in to photograph and log the hole dimensions and location.

The holes were repaired by wet welding rolled steel patches, generally 100mm x 100mm, over the holes. Tapered steel plugs were also utilised on smaller holes. Hydroweld FS 3.2 Wet Welding Electrodes were used exclusively on the project.

A pile was deemed to be complete once it could hold 70psi pressure for 30 minutes.

Water depth was to a maximum of 30m for the project. This required a decompression chamber to be on site for all dives where in water decompression was to be used. All plant and equipment for the project had to be shipped in by barge.