Underwater Pipeline at Port Kembla
A new 10 inch wharf line has recently been completed by V. G. Saunders Pty Limited for BP Australia Limited at its Port Kembla installation. The line runs for a distance of 4,700 feet (1.4km) from the installation to the tanker mooring berth on the north side of the harbour.
The new pipeline replaces a previous 8 inch line.The whole of the pipeline was cement lined, the underwater and underground sections by spin lining, the remainder by the “in-situ” method of lining. The underwater section of line has a Polytec coating and 1.5 inch of gunite for mechanical protection and dead weight.
The underwater section of the pipeline was fabricated into 90 feet (27m) flange lengths at V. G. Saunders’ Sydney workshop and, following testing, etc., was built up around steel boxes to form a truss for transport to the site at Port Kembla. The design of the pipe truss and subsequent handling was based on limiting the stresses in the pipe due to bending. All single lengths of pipe were handled with a special truss.
All underwater work, which included excavating a trench, laying and testing of the pipes and subsequent back filling, was carried out by the Commercial Diving Service of Wollongong. The pipe lengths were laid approximately 4 feet (1.2m) below the harbour bottom in a trench opened up using an air lift pump. This was the only means of excavation available without damaging existing pipelines against which the new line was laid.
Each of the lengths of underwater pipeline was handled with a 60 foot (18m) long 24 inch diameter tube which was divided into six compartments. When attached to the pipes and inflated, the tube and pipe were easily handled and positioned by the diver.
As each section of pipe was joined up with flanges, the section was pressure tested from the shore.