Author: Shawn Henderson, P.E.
Henderson & Associates provides project management and Professional Engineering drawings for Classed ship refit. We combine years of practical at-sea experience with formal training in ocean engineering. Henderson & Associates has pioneered innovative techniques for conducting refit of components and hull structure beneath the waterline. Professional Engineers are registered and licensed through the Florida Board of Professional Engineers as well as maintain active memberships with specific engineering societies (the Society of Naval Architects and Marine Engineers, the American Welding Society, the American Society for Non-Destructive Testing).
Project: ABS aluminum hull retrofit
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Tight coordination between the Professional Engineer, certified welders, qualified divers, ABS and the Client can be challenging but with good foresight and communication can be accomplished efficiently.
NAVAL ARCHITECTURE – meet all design criteria Codes and Standards
A weld plan is developed to ensure high quality and give direction to the welders. Aluminum hulled vessels require careful development of ABS approved welding procedures for welding to the hull. ABS pre-approved and traceable pipe, plate, welding filler, welders and welding processes is required. Additional hydrostatic testing may be required in-situ for through hull penetrations. Aluminum has a higher specific heat capacity and thermal conductivity than carbon steel. Due to this it is critical to have a hyperbaric barrier between the hull and the surrounding seawater to inhibit quenching of the weld zone and subsequently higher levels of entrapped porosity within the welds. Typical welding processes for aluminum are GTAW (gas tungsten arc welding) or GMAW (gas metal arc welding) with a mandatory pre-heat of the base metal to remove moisture. ABS approved design drawings are issued by the professional engineer for modification of the hull structure. ABS will require NDE (non-destructive examination) of the hull welds to ensure quality levels are met.
SHIP-FITTING PROJECT MANAGEMENT – ensure ABS approved design drawings are followed
Different plate locations within the same hull can require more aggressive cleaning to produce a pure weld puddle. Electrode batch quality can vary. GTAW can produce higher quality welds because the process demands greater control of the welding, however GTAW also requires more welder skill and has a lower deposition rate.
Please contact us for your next ship structural refit beneath the waterline.
Shawn Henderson, P.E.