Original Date: 02/10/2003
Revision Date: 01/18/2007
Best Practice : Welding Process Improvements
Bender Shipbuilding and Repair Company, Inc. developed and implemented new welding processes and controls to maximize productivity and reduce cost. The company introduced exciting new technical innovations that greatly improve the quality of ship welds while optimizing labor resources significantly reducing labor time in hull completion, and increasing overall welding productivity while reducing costs.
In 1998, Bender Shipbuilding and Repair Company, Inc. implemented an aggressive welding process improvement program to evaluate welding methods and develop and implement more efficient procedures where needed. A welding improvement committee of employees and contractors directly involved with welding was established. They devised methods to measure quality output, and launch accountability standards, and researched and implemented new technology, providing innovative solutions to existing challenges.
Bender’s primary welding processes for plate and attachments are Flux Cored Arc Welding (FCAW) and Submerged Arc Welding (SAW). Prior to 1998, there was no process to identify welds by employees, or by labor shift. Since welder efficiency evaluation procedures were not fully developed, there was no process to measure daily activities of individual welders. Because ceramic backing welding procedures were not fully developed, no Flux Core Welding Procedure Specification (WPS) existed for one-sided welds, and no process was in place for one-sided SAW. Temporary strong-backs, utilized during the welding process, were resulting in excessive re-work.
Bender recruited a new welding manager who was highly skilled and experienced in all types of welding to evaluate existing methods and develop more efficient welding procedures. His wide range of knowledge was utilized in designing and implementing new welding procedures as well as the developing measurement tools for studying welds and individual welders. Welder efficiency work sheets were introduced to the welding foremen as the new method to track weld footage and welder performance. The best welders in the shipyard were evaluated to determine the performance baseline. Difficulty factors were assessed to each weld job in order to determine the time required to complete each task. From this, a spreadsheet was developed to weigh the following factors: size of weld (1/4, 3/16, or 5/16); difficulty factor based on kind of weld and location of weld; vertical versus overhead weld; length of weld; and actual hours worked by the employee. The result was an efficiency rating for each welder. This daily report allowed the welding foremen to evaluate their staff and make changes as required. Welders became accountable for their work quality and quantity.
With changes to tracking a welder’s performance came changes to the welding processes in the shipyard. Aluminum fit-up strong-backs, attached with studs, were incorporated for structure plate fit-up. In 1999, Bender developed both a manual and an automatic oscillator Flux Core Arc Welding WPS for welding groove joints with ceramic backing, increasing efficiency by 33%. In 2000, a one-sided sub arc WPS was developed for welding groove joints 100% from one side, doubling weld footage and eliminating attaching strong-backs to flip plates in order to weld back-sides. A flux covered copper backing supports and forms the back side of the weld, eliminating back gouging. Welder identification procedures were developed for structure and pipe to identify which welder completed a specific weld. In 2001, one-sided SAW procedure specifications were introduced.
American Welding Society (AWS) certification programs were implemented in 2000, and are now tools used for measuring welder skills. These programs are Certified Welding Educator, Certified Welding Inspector (CWI), and Certified Welding Supervisor (CWS). As of September 2002, Bender has 17 CWSs employed in its shipyard. The CWS program teaches industry skills that include material and labor cost management. The CWI and CWS programs educate welding supervisors in both welding quality and quantity issues. Following CWS certification, the first hull unit fabricated in the shipyard was completed in 2600 welding hours, a reduction of 400 hours from pre- CWS. The AWS certification realized an immediate 15% increase in welding productivity.
Lincoln Electric introduced a new technology, Surface Tension Transfer (STT), a controlled short-circuiting transfer process that adapts its waveform to the physics of the welding arc and metal transfer. STT reduces spatter by cutting back the pinch force when the liquid bridge of a short is about to break into an arc. Bender harnessed this technology, and with modifications developed in-house, created an STT/SAW and STT/FCAW process for welding deck sockets on military sealift vessels. Welding the deck sockets, or tie-downs, is an enormous task involving thousands of sockets and countless man-hours of welding labor. Bender’s innovative new process reduced the cost and increased welder efficiency by a significant amount. Its aggressive search for an optimal solution, coupled with technical innovation, generated a cost and time efficient process that is becoming a shipyard standard.
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