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William Bong,

president of Arcmatic Welding Systems

History of Electroslag in USA and how Arcmatic was born

 

  There was a boom in High Rise building fabrication in California during the late 1960's through the 1980's. During that time, One of the principals of Arcmatic Welding Systems developed a method is increasing the speed and quality of welding moment plates (stiffeners) into High Rise building columns. The following structural steel fabricators were using the process extensively:

 

  1. Pittsburgh Des Moines Steel (Santa Clara, CA)
  2. Pittsburgh Des Moines Steel (Fresno, CA)
  3. Bethlehem Steel (Pinole Point, CA)
  4. US Steel - American Bridge Div (South San Francisco, CA)
  5. US Steel - American Bridge Div (Antioch, CA)
  6. US Steel - American Bridge Div (Los Angeles, CA)
  7. The Herrick Corporation - (Hayward, CA)
  8. Kaiser Steel - (Fontana, CA)
  9. Kaiser Steel - (Napa, CA)
  10. And others throughout the United States
      

 

 Between the late 1960's and late 1980s, it is estimated that these fabricators collectively welded over a million stiffeners with the electroslag welding process in Northern and Southern California. Two of the tallest buildings in California were welded, using the electroslag welding process - The Bank of America building in San Francisco, and the twin tower Security Pacific buildings in Los Angeles. Countless smaller buildings were also welded during this period of time in the greater San Francisco bay area, the Los Angeles basin, and the San Diego area. In (1970) I was working with several fabricators that were trying to solve the problem of welding closure weld on a moment plate in box columns. Prior to the advent of electroslag welding, fabricators would weld three plates of a box column together, then insert the moment plates into the box columns and weld all three sides to the three sides of the box. When the final cover plate was attached, the only way to make a full penetration weld was to slot the flange and spend a week filling in the final side of the moment plate. As High Rise building got much taller in California, the box columns on the bottom floors had continuity plates as thick as 6-inches.

 

These welds were generally done with a SubArc Squirt welder, and took weeks to complete. When the electroslag process came along, a gap was left between the stiffener and the final cover plate. A hole was then cut in the top and bottom plates to allow for a sump and run-off - we dubbed this the "keyhole" welding procedure. It was found that the Vertical-Rate-of-Rise (VRR) had to be less than ½ IPM to produce a sound weld. This slower VRR created a weld nugget that was strong enough to support the stress created by the solidification of the weld puddle. One of the principals of Arcmatic was instrumental in setting creating the welding procedures to solve this most troublesome problem. In Asian countries, structural steel fabricators use box columns, instead of rolled H-Beam columns for high-rise building fabrication. To weld moment plates into a box columns, they also use the electroslag "keyhole" methods developed by California fabricators the 70s. Over the last 35 years, every box column in the world has been made using the electroslag keyhole process. The electroslag process isn't anything new. Millions of welds have been made in high-rise buildings all over the world. So far, we don't have a record of any failures. Another popular process for welding continuity plates into building columns was the multipass gasless flux cored wire process. This process was also used for field welding beam flanges to column flanges for field erection. The Northridge Earthquake and the Loma Prieta Earthquakes provided a "real world" test to compare all of the welding processes.

 

The Structural Steel welding industry is well aware that, over one billion dollars in crack repairs were needed, after the Northridge earthquake, to repair weld cracks propagated in welds made with the gasless flux cored wire process. Not one failure or one crack propagation was initiated in any of the hundreds-of-thousands of welds made on continuity plates welded with the Electroslag welding process. In the history of the use of electroslag welding in the United States, to this authors knowledge, only one weld failure has ever occurred in an electroslag weld - where thousands of failures have occurred with the Submerged Arc Welding Process (SAW), The Gas Shielded Flux-Cored Arc Welding Process, and the Gasless Flux-Cored Arc Welding Process during this same period of time. This one failure occurred on bridge flange in tension - subjected to reversal stress loading. Extensive research by a "blue ribbon" committee of University professors, and welding engineers determined that a bad weld repair, not the electroslag welding process, caused this one failure. If the same bad repair had been done with any other process, the weld would still have failed. In the early 1980's, the Federal Government, under the guidance of the Federal Highway Administration (FHWA) set about an extensive investigation of the electroslag welding process with the purpose of increasing the physical properties for welding tension flanges on bridges, subjected to reversal stress loading. During this research period, they placed a moratorium on welding flanges with the process. The process continued to be used for structural applications under the AWS D1.1 Structural Code. Contracts were given to, Northwestern University, Lehigh University, and the Oregon Graduate Institute (OGI). OGI came up with the best ideas to improve the physical properties of the electroslag welding process.

 

They accomplished this by reducing the weld gap from 1-1/4", down to ¾" wide. The reduction in gap reduced the size of the Heat Affected Zone (HAZ) and increased the speed of the process. The second major advance was to use a Metal-Cored Welding Wire, instead of a Solid Wire. Using a Metal Core welding wire made it much easier to change the wire chemistry. Nickel (Ni) was added to the chemistry of the wire to help increase the impact properties of the weld metal. The density of a Metal-Core welding wire is much less than a solid wire. This decrease in density allows the wire to melt as soon as it comes in contact with the 3500-degree molten weld puddle. The fast melting of the weld wire resulted in a shallower molten weld metal pool that lowered the resultant weld "form factor" - reducing or eliminating the potential for weld cracking. The process greatly improved the mechanical properties of an electroslag weld.OGI conducted the initial research between 1980 and 1985. By the end of 1985 most of the basic research had been completed. The task then undertaken by FHWA was to convince the bridge industry of the superiority of the newly developed process. To accomplish this goal, they gave a contract to OGI to go to every State and demonstrate the process to Department of Transportation (DOT) Management. They called this new HIGH QUALITY electroslag welding process, Narrow Gap Improved - ElectroSlag Welding (NGI-ESW). In 1993 Arcmatic Welding Systems was formed to take advantage of this superior welding process.

 

Since the principals of Arcmatic had already designed and put into production the Continuity Plate welding process, using the original electroslag welding process (ESW); they felt that the advantages of welding Continuity Plates with the new NGI-ESW process would give better physical weld characteristics to an already superior welding process. Welding Continuity plates with multipass gasless, or gas shielded flux-core welding wire process has inherent problems that the NGI-ESW process eliminates. First, the weld has to be made into a backup bar that, in most cases should be removed and back gouged to insure a sound weld on the top and bottom of the moment plate. Second, each time a pass is made in a multipass weld, the base metal is first heated by the weld bead and then cools and stresses the weld joint. This puts the weld in tension. Each time a weld pass is made, tension in the weld joint is increased. The "K-Area" of the column is already work hardened and highly stressed because of the multiple rolling actions created when the column is formed. When a multipass weld passes over the "K-Area" of the column, the stress/strain increases. If this stress/strain becomes excessive, small cracks occur. Then either by fatigue or large stress/strain (as in the case of an earthquake) the small cracks will propagate and a weld failure will follow. The 3500-degree molten flux puddle floating on top of the molten weld metal preheats the parent material, eliminating the need for preheating. The weld is done in one pass.

William Bong,

president of Arcmatic Welding Systems

History of Electroslag in USA and how Arcmatic was born

 

  There was a boom in High Rise building fabrication in California during the late 1960's through the 1980's. During that time, One of the principals of Arcmatic Welding Systems developed a method is increasing the speed and quality of welding moment plates (stiffeners) into High Rise building columns. The following structural steel fabricators were using the process extensively:

 

  1. Pittsburgh Des Moines Steel (Santa Clara, CA)
  2. Pittsburgh Des Moines Steel (Fresno, CA)
  3. Bethlehem Steel (Pinole Point, CA)
  4. US Steel - American Bridge Div (South San Francisco, CA)
  5. US Steel - American Bridge Div (Antioch, CA)
  6. US Steel - American Bridge Div (Los Angeles, CA)
  7. The Herrick Corporation - (Hayward, CA)
  8. Kaiser Steel - (Fontana, CA)
  9. Kaiser Steel - (Napa, CA)
  10. And others throughout the United States
      

 

 Between the late 1960's and late 1980s, it is estimated that these fabricators collectively welded over a million stiffeners with the electroslag welding process in Northern and Southern California. Two of the tallest buildings in California were welded, using the electroslag welding process - The Bank of America building in San Francisco, and the twin tower Security Pacific buildings in Los Angeles. Countless smaller buildings were also welded during this period of time in the greater San Francisco bay area, the Los Angeles basin, and the San Diego area. In (1970) I was working with several fabricators that were trying to solve the problem of welding closure weld on a moment plate in box columns. Prior to the advent of electroslag welding, fabricators would weld three plates of a box column together, then insert the moment plates into the box columns and weld all three sides to the three sides of the box. When the final cover plate was attached, the only way to make a full penetration weld was to slot the flange and spend a week filling in the final side of the moment plate. As High Rise building got much taller in California, the box columns on the bottom floors had continuity plates as thick as 6-inches.

 

These welds were generally done with a SubArc Squirt welder, and took weeks to complete. When the electroslag process came along, a gap was left between the stiffener and the final cover plate. A hole was then cut in the top and bottom plates to allow for a sump and run-off - we dubbed this the "keyhole" welding procedure. It was found that the Vertical-Rate-of-Rise (VRR) had to be less than ½ IPM to produce a sound weld. This slower VRR created a weld nugget that was strong enough to support the stress created by the solidification of the weld puddle. One of the principals of Arcmatic was instrumental in setting creating the welding procedures to solve this most troublesome problem. In Asian countries, structural steel fabricators use box columns, instead of rolled H-Beam columns for high-rise building fabrication. To weld moment plates into a box columns, they also use the electroslag "keyhole" methods developed by California fabricators the 70s. Over the last 35 years, every box column in the world has been made using the electroslag keyhole process. The electroslag process isn't anything new. Millions of welds have been made in high-rise buildings all over the world. So far, we don't have a record of any failures. Another popular process for welding continuity plates into building columns was the multipass gasless flux cored wire process. This process was also used for field welding beam flanges to column flanges for field erection. The Northridge Earthquake and the Loma Prieta Earthquakes provided a "real world" test to compare all of the welding processes.

 

The Structural Steel welding industry is well aware that, over one billion dollars in crack repairs were needed, after the Northridge earthquake, to repair weld cracks propagated in welds made with the gasless flux cored wire process. Not one failure or one crack propagation was initiated in any of the hundreds-of-thousands of welds made on continuity plates welded with the Electroslag welding process. In the history of the use of electroslag welding in the United States, to this authors knowledge, only one weld failure has ever occurred in an electroslag weld - where thousands of failures have occurred with the Submerged Arc Welding Process (SAW), The Gas Shielded Flux-Cored Arc Welding Process, and the Gasless Flux-Cored Arc Welding Process during this same period of time. This one failure occurred on bridge flange in tension - subjected to reversal stress loading. Extensive research by a "blue ribbon" committee of University professors, and welding engineers determined that a bad weld repair, not the electroslag welding process, caused this one failure. If the same bad repair had been done with any other process, the weld would still have failed. In the early 1980's, the Federal Government, under the guidance of the Federal Highway Administration (FHWA) set about an extensive investigation of the electroslag welding process with the purpose of increasing the physical properties for welding tension flanges on bridges, subjected to reversal stress loading. During this research period, they placed a moratorium on welding flanges with the process. The process continued to be used for structural applications under the AWS D1.1 Structural Code. Contracts were given to, Northwestern University, Lehigh University, and the Oregon Graduate Institute (OGI). OGI came up with the best ideas to improve the physical properties of the electroslag welding process.

 

They accomplished this by reducing the weld gap from 1-1/4", down to ¾" wide. The reduction in gap reduced the size of the Heat Affected Zone (HAZ) and increased the speed of the process. The second major advance was to use a Metal-Cored Welding Wire, instead of a Solid Wire. Using a Metal Core welding wire made it much easier to change the wire chemistry. Nickel (Ni) was added to the chemistry of the wire to help increase the impact properties of the weld metal. The density of a Metal-Core welding wire is much less than a solid wire. This decrease in density allows the wire to melt as soon as it comes in contact with the 3500-degree molten weld puddle. The fast melting of the weld wire resulted in a shallower molten weld metal pool that lowered the resultant weld "form factor" - reducing or eliminating the potential for weld cracking. The process greatly improved the mechanical properties of an electroslag weld.OGI conducted the initial research between 1980 and 1985. By the end of 1985 most of the basic research had been completed. The task then undertaken by FHWA was to convince the bridge industry of the superiority of the newly developed process. To accomplish this goal, they gave a contract to OGI to go to every State and demonstrate the process to Department of Transportation (DOT) Management. They called this new HIGH QUALITY electroslag welding process, Narrow Gap Improved - ElectroSlag Welding (NGI-ESW). In 1993 Arcmatic Welding Systems was formed to take advantage of this superior welding process.

 

Since the principals of Arcmatic had already designed and put into production the Continuity Plate welding process, using the original electroslag welding process (ESW); they felt that the advantages of welding Continuity Plates with the new NGI-ESW process would give better physical weld characteristics to an already superior welding process. Welding Continuity plates with multipass gasless, or gas shielded flux-core welding wire process has inherent problems that the NGI-ESW process eliminates. First, the weld has to be made into a backup bar that, in most cases should be removed and back gouged to insure a sound weld on the top and bottom of the moment plate. Second, each time a pass is made in a multipass weld, the base metal is first heated by the weld bead and then cools and stresses the weld joint. This puts the weld in tension. Each time a weld pass is made, tension in the weld joint is increased. The "K-Area" of the column is already work hardened and highly stressed because of the multiple rolling actions created when the column is formed. When a multipass weld passes over the "K-Area" of the column, the stress/strain increases. If this stress/strain becomes excessive, small cracks occur. Then either by fatigue or large stress/strain (as in the case of an earthquake) the small cracks will propagate and a weld failure will follow. The 3500-degree molten flux puddle floating on top of the molten weld metal preheats the parent material, eliminating the need for preheating. The weld is done in one pass.