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Exothermic Welding for CVN

Utilizing exothermic welding for splicing large diameter power cables on CVN 78 is expected to reduce labor hours for installation, as well as preventive and corrective maintenance. Erico Products photo

Objective

The objective of this Navy Metalworking Center (NMC) project was to thoroughly evaluate the proposed exothermic welding and insulation processes for splicing the Electromagnetic Aircraft Launch System (EMALS) shipboard power cables and other applications on CVN 78 Class carriers. A shipboard installation and repair procedure was also developed and approved for use.

Background

The Future Aircraft Carrier Program Office supports the use of thermite (exothermic) welding for performing multi-cable, copper conductor splices for Navy shipboard power applications as a means of reducing total ownership cost. Thermite welding requires no external source of heat or current and is expected to reduce the total number of man-hours required for installation, as well as man-hours required for preventive and corrective maintenance. However, the process was not approved for Navy shipboard applications. The effects of shipboard environmental conditions on weld quality were not fully understood, and Navy and shipbuilder experience with the process was very limited.

Technical Approach

This NMC project identified applicable ship and system requirements for the Electromagnetic Aircraft Launch System (EMALS) power cables, as well as other applications on CVN 78 Class carriers, and determining via testing whether the proposed exothermic welding process identified for use during installation of the shipboard power cables meets system and shipboard performance requirements.

Benefits

Although life-cycle cost benefits associated with a more efficient multi-cable connection method are expected, there is no comparison data available to understand any cost impacts at the acquisition level. Qualitative benefits include reduced risk to quality and schedule; reduction in man-hours expected for installation as well as preventive and corrective maintenance of the EMALS cable system; increased system reliability and availability; and the creation of enhanced, repeatable, cost-effective installation and repair procedures. This project will potentially lead to a Fleet-wide process for splicing power cables, which is especially applicable to high-current applications, such as electric propulsion and pulse-energy systems.

Implementation

The CADWELD® Exolon exothermic welding process has been shown to be very robust; overall performance and quality of these splices are not affected by the environmental conditions at the time of fabrication of the splice. In addition, insulation of these splices using the recommended 3M insulation products is not affected by the environmental conditions at the time the insulation is applied. The project test program has verified that the electrical and mechanical properties of splices made using the developed installation procedure meet the test plan requirements for splicing EMALS power cables aboard CVN 78 Class carriers. Huntington Ingalls Industries - Newport News Shipbuilding (NNS) will implement the NAVSEA-approved procedure to complete installation of the EMALS on CVN 78 Class carriers in the third quarter of fiscal year 2013.

In June 2015, the Navy conducted a "dead-load" test of the new EMALS aboard Pre-Commissioning Unit Gerald R. Ford (CVN 78). A video of the dead-load test is available on YouTube.

Status

Completed

Stakeholder

Nicholas McGregor
PMS 378

Partners

Naval Air Systems Command (NAVAIR)
Naval Sea Systems Command (NAVSEA)
Naval Surface Warfare Center, Carderock Division
Newport News Shipbuilding
PMS 378 Future Aircraft Carriers