Design of Shiploader Access System for Shark Bay Resources in Western Australian, which involved FEA structural analysis, selection of all major components and design of control system.
The Shiploader Access system is located on the side of a ship loader platform. It is a pivoting gangway that is moved by two hydraulic cylinders connecting the gangway to the ship platform. The gangway can pivot up 30 degrees and down 20 degrees from horizontal. On the end of the gangway is a pivoting stairway and platform. A single hydraulic cylinder positions the stairway relative to the gangway and is used to maintain the stairs in a level position. A storm lock is used to support the gangway in the level position when not in use.
The access system allows access to bulk carriers from 17,000 tons to 40,000 tons over a range of loading heights. The walkway conforms to AS 1657-1992 “Fixed platforms, walkways, stairways and ladders” and is capable of operating over a vertical height range of 10.8 meters. The access system is designed for a maximum operational wind speed of 23 meters per second. The design configuration utilises a gangway and stairway hinged together. The gangway is 16 metres long and is pivoted to the fixed shiploader structure by two luffing cylinders. It has a continuous WEBFORGE tread system and can be used for access over an angle range of minus 20 to plus 20 degrees.
The angle of the gangway and stairway are continuously monitored by two rotary encoders measuring the operating angles. These encoders form part of the speed control and self-levelling functions. An ultrasonic proximity sensor at the outer end of the stairs is used for feedback to the boom-luffing control circuit, to slow and then stop the stairs and gangway when approaching the deck. Control signals from the two rotary encoders and the ultrasonic sensor are sent to the PLC for processing. The control system is integrated into the ship loader controls system.
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