Structural Fairing Process Improvement

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Project Participants: Huntington Ingalls Industries, Inc.

Project Start: July 2014

Thermal and mechanical straightening are the current processes used to correct distortion in shipbuilding. Although effective, these processes are largely trial and error-based with vague operational guidance available. Lack of specific guidance on processes lead to the following effects: significant structural damage, costly rework, process delays, and unknown quantities of residual stress in structural members. Instances of crippled structures due to overheating distorted thin material have not only caused increased rework but has also instilled engineering concerns about these levels of unknown stress buildups caused by the current process.

The objective of the Structural Fairing Process Improvement project is to investigate the current procedures used to straighten deck plate, gain an understanding of the limits to which distortion can be safely brought into tolerance without compromising material strength, and revise the guidance procedures used by fairing personnel.  The goal is to revise current flame straightening patterns and determine the most effective pattern for various steel grades and thicknesses that applies the lowest amount of heat into the plates to achieve the flatness requirements. The revised patterns will be included in handbooks, which will be distributed to the straighteners and supervisors, and will also include  application  methods  and  instruction  on  temp  stick  readings,  limits,  and  the process steps where fairness checks will be required.

The improved process, once implemented, could potentially save an estimated $776K per DDG 51 Hull. These savings will result from reductions in hull rework, flame straightening labor, compartment completion labor, and coating rework.

Project Related Reports & Documents