For more than 50 years, NASA has relied on welding to make the impossible possible. Launching satellites into orbit, sending probes to distance planets, and even landing a man on the moon – none of it would have been possible with advances in the field of welding.
Today, NASA is poised to take their next big step into deep space with the Space Launch System. Standing nearly 400 feet tall, it will be the largest and most powerful rocket ever designed by mankind. It will help take humans back to the moon, and even on newer more exciting destinations like asteroids and Mars. And just like all the rockets and machinery before it, the Space Launch System will rely heavily on a new advancement in welding – the Vertical Assembly Center.
Debuting on September 12, 2014, the Vertical Assembly Center is the largest welding tool in the world. It will help bring together the massive core stage of the SLS one piece at a time.
At 800 miles long, the Trans-Alaska Pipeline has been described as one of the most historic welding and construction projects in history. For three years, tens of thousands of welders braved the harsh climate and terrain of Alaska’s wilderness to weld together the 48-inch diameter of the pipeline. And since then, more than 17 billion barrels of oil have flowed from the Prudhoe Bay oil field in Northern Alaska down to Valdez Bay.
Construction of the massive pipeline began in 1975 – at a time where construction was in a slump throughout the United States. Because of this, the project attracted workers from all around the country. In fact, the men who welded the pipeline came all the way from the Pipeliners Local 798 Union out of Tulsa, Oklahoma. This group specialized in providing welders for large-scale pipeline projects, and the Trans-Alaska Pipeline was probably the largest up to that point.
Because of the immensity and importance of the Pipeline, the hiring process was very intense. Welders were first put through a certification process that involved several test welds. If the welder failed any of the test welds, they were not hired and were not allowed to be tested again for several weeks. The reason for the stringent hiring process was likely due to the fact that welders on the project were welding a new steel pipe thicker and larger than most of them had ever worked on before.
The first step to the pipeline construction involved clearing the 800-mile path laid out by surveyors. Workers slowly trudged their way through forrest, brush, and obstacles using chainsaws and bulldozers. Once the path was cleared and OKed by surveillance officers and engineers, holes were drilled and filled with gravel and water. These served as the foundations for the Vertical Support Members that held up the pipeline using semicircular supports. The VSMs were carried by crane in 40 or 80-foot segments, lowered into the holes, and then welded together. Quality control engineers inspected the welds using X-ray.
With several VSMs already in place, workers officially laid the first portion of the Trans-Alaska Pipeline on March 27, 1975.
Several 40-foot segments were places atop the supports, welded together, and coated in concrete. And so began the two-year long process of welding construction on the pipeline.
Welds on the pipeline were originally expected to meet an average impact value of 20 ft-lb and at least 15 ft-lb. The joints were made using submerged arc welding and a wire that contained 3% nickel. About 80,000 lb of that wire were used throughout the entirety of the Pipeline project.
Mid-way through the construction process, the U.S. Department of the Interior and a pipeline coordinating group representing the state of Alaska instituted more stringent requirements for weld toughness. Instead of the conventional electrode that was originally being used for the majority of field welds, new requirements necessitated a higher quality electrode using an E8010-G filler metal. This electrode had to be flown into Alaska from Germany. It was an electrode the most welders on the project had never used before.
Throughout the project, welders worked inside protective aluminum enclosures that shielded them from the wind and other harsh weather conditions. It also gave them the lighting they needed to work through the night. Similar to the VSMs, pipeline welds were also inspected using X-ray. Inspectors traveled alongside the welding crews in vans where X-ray film was automatically processed and inspected.
On May 31, 1977 the final pipeline weld took place. Pump station and terminal construction still needed to be completed, but the pipeline was able to be put into operation without them being completed. In a sense, the hard work had already been done, and just three months later the tanker ARCO Juneau sailed out of Valdez with the first load of oil that had traveled through the Trans-Alaska Pipeline.
So impressive was the project and the welding done on it, that in 2002 the American Welding Society declared the Trans-Alaska Pipeline an outstanding development in welded fabrication. The Alyeska Pipeline Service Company was presented with an award and congratulated on the immense project they helped create.
By law, Alyeska is required to remove the pipeline once oil extraction in the Prudhoe Bay is complete. Improvements in reducing flow-rates seem to suggest the oil could be flowing through the pipeline until at least 2075 – meaning this welding wonder could last 100 years.
For 30 years, the Space Shuttle stood as the beacon of American spaceflight. Between 1981 and 2011, a total of 135 missions were launched from Kennedy Space Center in Florida. Thanks to the Space Shuttle, numerous satellites and interplanetary probes were launched (including the Hubble Space Telescope), important science experiments were conducted in orbit, and the International Space Station was constructed.
And all of this was made possible thanks to the welding wonders that brought the Shuttle’s external tank to life.
The external tank was designed by the Martin Marietta Corporation, and manufactured and assembled by the Lockheed Martin Space Systems Company at NASA’s Michoud Assembly Facility in New Orleans, Louisiana. It was the largest and heaviest component of the Space Shuttle. It contained the liquid hydrogen fuel and liquid oxygen oxidizer which were supplied to the three Space Shuttle Main Engines during lift-off. It was also the only Space Shuttle component that was not recovered after launch. The tanks simply broke apart before impacting the ocean.
Since its first mission in 1981, the tank went through two important upgrades. Starting with the Standard Weight Tank and ending with the third-generation Super Lightweight Tank, the changes made were done to reduce the weight of the tank and increase the Shuttle’s payload capacity.
The original tank, which was built until 1983, weighted about 76,000 pounds when loaded with fuel and oxidizer. The basic structure was made of aluminum alloy 2219. Tank sections, which were comprised of many thicknesses of aluminum sheeting, were assembled using gas tungsten arc welding.
This tank lasted for just six Space Shuttle missions, with the last of the Standard Weight tanks being flown on Challenger’s STS-7 mission in 1982.
The year before that, Michoud had begun production on the Lightweight Tank, which trimmed about 10,000 pounds from the tank that preceded it.
The weight reduction was accomplished through several different methods. First, the thickness of several aluminum skin panels was reduced, and several stringers in the liquid hydrogen tank were eliminated. Dome caps which were chemically milled on one side only, were now milled on both sides to reduce weight without reducing strength. A new titanium alloy, which was stronger, lighter and less expensive, was also used by the Solid Rocket Booster attachments.
New welding processes also made the Lightweight Tank production more labor and cost efficient. In 1984, the Marshall Spaceflight Center adopted Variable Polarity Plasma Arc welding as the method used in the tank construction. Terry Hibbard, Lockheed Martin’s vice president for the external tank program said: “In the early 1980s, we developed with NASA Marshall the variable polarity plasma arc welding process. We used those processes for the 2195, plus a hybrid process where the plasma arc alternates current and does some cathodic cleaning at the torch,”.
The Lightweight Tank flew on 85 Space Shuttle missions, with its last flight being aboard STS-99 in 2000.
In 1993, NASA had asked Lockheed Martin to develop a new high-strength, light-weight replacement for the aluminum alloy Al 2219 being used on the External Tanks. After years of research, Lockheed Martin, Reynolds Aluminum, and the labs at Marshall Space Flight Center were able to successfully develop a new alloy known as Aluminum Lithium Al-Li 2195 – which reduced the weight of the External Tank by another 7,500 pounds.
This Super Lightweight Tank gave the Shuttle the chance to carry heavy components for the assembly of the International Space Station. However, the new alloy used in the tank’s construction did not come without problems.
NASA and Lockheed Martin Engineers faced several difficulties as they learned to form, weld, and repair the new material. Myron Pessin, former Chief Engineer for the External Tank Program, noted that weld repairs were a significant challenge.
Many weld lands on the Super Lightweight Tanks were increased in thickness by up to 0.35″ to allow more margin for potential weld repairs. A “second generation” of the Super Lightweight used a different alloy in the intertank thrust panels. The change allowed for even more weight savings – though they were offset by the conversion back to Al 2219 for the dome gores – which were easier to weld, and which drastically reduced repairs.
With repair welds becoming more difficult to make, and production costs increasing on the tank, NASA began researching alternative welding techniques. Project Managers eventually chose the friction stir process, which produced a stronger joint than the fusion arc welding used in the earlier Lightweight Tank. Another significant benefit of friction stir welding was that it had far less elements to control. For example, in fusion welding you must control purge gas, voltage, amperage, wire feed, travel speed, shield gas, and arc gap. However, in friction stir there are only three process to control: rotation speed, travel speed, and pressure.
Friction stir welding works by rotating a dowel between 180 to 300 revolutions per minute depending on the thickness of the material. The tip of the dowel is forced into the material, and as it continues rotating, friction heat softens the area around the pin and forces it to forge and create a bond with the other material.
STS-132 in 2010 was the first mission to fly using an External Tank that was constructed using friction stir welding. It featured friction stir welds on two of the liquid hydrogen tank barrels. STS-134 was the first mission which featured friction stir welds on all four liquid hydrogen tank barrels and the liquid oxygen barrel.
In the end, welding played a huge part in the decision-making for certain alloys and construction methods used on the Space Shuttle’s external tank.
After it’s retirement in 2011, NASA was left without a working spacecraft to take it’s astronauts into space. The Russian Soyuz spacecraft is now the main vehicle used by NASA astronauts to get to and from the International Space Station. But the lessons learned during its construction – from alloys to welding to construction methods – will live on in future NASA efforts.
“Like a grand and miraculous spaceship, our planet has sailed through the universe of time. And for a brief moment, we have been among its many passengers.” So goes the opening line for the nearly 32-year-old attraction at Disney’s Epcot Center: Spaceship Earth.
At 182 feet tall, Spaceship Earth stands as one of Disney Imagineering’s most iconic structures ever built. And at the time of its construction, it was just seven feet shy of being the tallest attraction at Walt Disney World. That record went to Cinderella Castle in Magic Kingdom.
Spaceship Earth was meant to symbolize the park’s theme of “bringing the world together through technology” – and they certainly accomplished that goal throughout the construction process.
“This was a very dramatic architectural statement Walt Disney Productions wanted to make,” explained Phil Lengyel, a publicity representative for Walt Disney World during the construction of Epcot in the early 1980s. “It was the first time we designed a structure first and then a ride system to go inside it. Disney has always built the attraction first, and Spaceship Earth is the first of its kind to be done this way. Then, again, Spaceship Earth is the only geosphere of its kind in the world.”
Disney designers originally planned Spaceship Earth as a geodesic dome – but after significant research, the project was expanded to a geosphere. Building a sphere brought with it some engineering challenges – specifically because the entire structure would have to be raised 20 feet off the pavement below.
The head designer for the Spaceship Earth project, Gordon Hoopes, said “‘we knew that having the entire sphere raised above the ground would cause substantial engineering problems but the psychological uplift for our guests would be worth it.”
In order to avoid excessive stress in the sphere, the three main structures were engineered separate from each other. These included: 1) the sphere structure, 2) the ride and show structure and 3) the utility structure. The sphere is constructed from steel wide-flange struts of A572 Grade 50 steel in three sizes. Its frame is penetrated by six support legs, an elevator shaft, and the ride tube. The ride itself is a spiraling floor unit consisting of concrete slabs on metal decks, all supported by steel beams and shop-welded plate girders. A support system in the attraction’s utility structure transfers all the loads from the sphere and most from the ride to the structure’s six legs.
In terms of welding for the project, most was done off-site.
“Whenever possible, structural steel assemblies were prefabricated in the shop or assembled on the ground prior to erection due to quality control and better working conditions,” said Jon Hine, WED project engineer for Spaceship Earth.
The structural steel fabricator and erector for the project was Tampa Steel Erecting, Co. And although Spaceship Earth is unique in design and construction, the project did not involve unusual welding processes. The techniques used for welding pieces of the giant geosphere were similar to those used in standard construction projects. In fact, the project was described as being similar to “putting up an erector set.”
“We just kept adding one piece on to another,” said Jon Hine.
The criteria for welding inspection, however, was very strict. Kanu Patel, Disney Imagineering’s chief structural engineer on the project said “our criteria were similar to those of Nuclear Power Plant Category I structures.” Because of this, semiautomatic submerged arc welding was the process selected for the full peneration weldments. For the plate girder fabrication, fully automatic submerged arc welding was used. In the field, however, shielded metal arc welding was used because of the fixed position welding required and the fact that there were so many welders skilled in that process at the time.
Throughout the construction process, both shop fab and field erection inspections were required – with a large emphasis on nondestructive testing. Disney Imagineering contracted the Atlanta-based LAW Engineering Testing Company to act as a consultant during materials testing.
“In some cases, due to the complex configurations of the many welded connections, radiography, ultrasonics, magnetic particle, and penetrant inspection were all used to ensure full coverage,” stated David Pacacha, project metals engineer for LAW Engineering Testing Co. “Continuous visual inspection on critical weldments was also required at some time. Approximately 4000 radiographic exposures were made on Spaceship Earth.”
During the construction process, up to 20 technicians were involved with the inspection process, and as many as six of those were conducting field inspections.
“In addition to nondestructive testing,” Pacacha said, “inspection of high-strength A325 bolted connections was required, which made for many ‘Spiderman’ adventures with the inspection wrench.”
Once the metal structure of the sphere was completed, 9 ft panels of galvanized sheet metal covered with neoprene rubber were fitted into the open space. These sheets were then sealed with a rubberized material, before the outer later of polished aluminum was put into place. These are the white tiles we see today that make up the exterior of Spaceship Earth.
“Fabrication started in October, 1980, and the first legs hit the site around December 1,” said Pacacha. “Field erection continued through all of 1981 and we were still erecting the exterior roofing panels around March or April of 1982.”
On June 1, 1982, 20 months after the start of fabrication, the exterior lights of Spaceship Earth were turned on for the first time. “It started at 9:00 p.m.,” Pacacha remembered. “It took eight minutes to get all the lights fully up, and that wasn’t including the very top of the sphere. The lights came on in stages . . . and then we started getting UFO reports!”
The construction of Spaceship Earth did not go unnoticed. In 1981, Frank J. Heger and Glenn R. Bell, both of Simpson Gumpertz and Heger – the firm hired to develop the pavillion’s design – received a Silver Medal from the James F. Lincoln Arc Welding Foundation for the design of the attraction’s support hub weldments. And in 1982, the sphere was honored as one of the top engineering projects of the year by the National Society of Professional Engineers.
Today Spaceship Earth stands as one of the most iconic theme park attractions in the world. Epcot draws in roughly 11 million visitors a year – and each of them have stared in wonder at the geosphere, never knowing the work and the welding that went into building it.
Standing thirty-three feet high and sixty-six feet long, Cloud Gates has become one of Chicago’s most iconic structures. Known by many as “the bean” (because of it’s resemblance to the tiny legume), the sculpture was designed by British artist Anish Kapoor. But it was brought to life thanks to the hard work of more than 100 metal fabricators, engineers, technicians, and yes, even welders.
Kapoor says the sculpture was inspired by liquid mercury, and so it is forged of a seamless series of highly polished stainless steel plates. In order to bring “the bean” and it’s outer shell to life, two companies on opposite sides of the country were hired. Performance Structures Inc. (PSI), in Oakland, California, and MTH, in Villa Park, Illinois.
Having in-depth experience creating shell structures, initially on ships and later on other art projects, PSI’s Ethan Silva was uniquely qualified for the shell structure fabrication task. Anish Kapoor asked the physics and art graduate to provide a small-scale model.Standing thirty-three feet high and sixty-six feet long, Cloud Gates has become one of Chicago’s most iconic structures. Known by many as “the bean” (because of it’s resemblance to the tiny legume), the sculpture was designed by British artist Anish Kapoor. But it was brought to life thanks to the hard work of more than 100 metal fabricators, engineers, technicians, and yes, even welders.
Kapoor says the sculpture was inspired by liquid mercury, and so it is forged of a seamless series of highly polished stainless steel plates. But underneath the plates is where the majority of the work took place.
In order to bring “the bean” to life, two companies on opposite sides of the country were hired. Performance Structures Inc. (PSI), in Oakland, California, and MTH, in Villa Park, Illinois.
Construction of the shell structure was lead by PSI’s Ethan Silva, who had previous experience in creating similar structures for ships and art projects.
Speaking to thefabricator.com, Si.va said “we basically worked on that project, making those parts, for about three years. It was a major task. And a lot of that time was spent figuring out how to do it and working out the details; you know, just perfecting it.”
The unique shape of the structure posed various problems for the fabricators during the making of the outer plates. Among them was the daunting task of plasma cutting the 1/4 – 3/8 inch thick 316L steel plates. Some of the largest plates weighed as much as 1,500 pounds.
“The real challenge was to get the mammoth plates to the precise-enough curvature,” said Silva. “And that was done by very accurately forming and fabricating the rib-system framework for each plate. That way we could accurately define the shape of each plate.” The immensity of this project meant a three-dimensional rolled has to be designed and built specifically for the Cloud Gate plates.
Afterwards, welders flux-core stitch-welded the curved plates onto the rib-system. Silva explained his liking of the flux-core process, saying “Flux-core is really a wonderful way to create structural welds…it gives you a great-quality weld and it’s very production-oriented and it has a good appearance.”
The work on the outer plates wasn’t done yet. For their picture-perfect appearance, the sheets were hand-ground and machine-milled to the thousandths-of-an-inch so they would all fit together perfectly. Fabricators used laser scanning equipment to check their dimensions, and then polished the plates and applied a protective film.
Once completed, the superstructure and plates were loaded onto semi-trucks and sent across the country to Chicago. A group of PSI workers were also sent to work with MTH staff in Chicago, who were now in charge of installing the sculpture and joining the pieces.
According to Lou Cerny, vice president of engineering and the project manager for MTH, the 30,000 pound substructure that supported the sculpture was one of the most difficult items they worked on.
“We started installing the truss system with two large fabricated 304 stainless steel O-shaped rings,” Cerny said. The photo above shows the structure’s rings help together by criss-crossing pipes. The frame between them is field-bolted and reinforced with GMAW and stick welding.
A suspension system was then used to assemble the shell over the substructure. Each of the 168 plates had its own hanging support system as it was put into place. It was set up this way to avoid over-stressing any joints on the system. Remarkably, the plates fit together on the structure perfectly.
“PSI did a tremendous job of fabricating the plates,” Cerny said. “I give them all of the credit for that, because in the end, it actually fit. The fit-up was excellent, which to me was amazing. We’re talking about, literally, thousandths of an inch. The plates came together with a closed edge.”
Silva said many people thought the work was done when the plates were put in. But the most important work of all had not been done – the welding of the plate seams. Plasma welding was done to provide the strength needed for the structure, and to avoid as much risk to the plates.
“The welds had to be full-penetration welds, but we had to weld from one side only—all from the exterior,” Cerny said. In order to achieve full weld penetration, workers used a custom-built chamber on the back-side of the plate. As the welder made his welds, the channel was flooded with inert gas and fed directly into the joint from the inside.
“We’re not talking about new technology—we’re talking about using the technology in a field condition under strange circumstances and modifying it to work,” Cerny said. “The heads were modified, cut at certain angles, and everything else was changed slightly. We did a lot of experimentation to get it to work, because it was all-position welding within the same run—meaning it’s right in front of you, vertically up, vertically down, and overhead. So you’re constantly adjusting your gas feed, your wire feed speed, how fast you’re traveling It’s something that the guys had to develop as they were working with it. There is no book that tells you that, unfortunately.”
With the welds completed, workers got started on the final phase of the project – polishing of the structure. The seam welds left many visible marks, which needed to be ground down using 60-grit zirconium paper on semiautomatic belt sanders. The next step called for the use of a special 400-grit ceramic sandpaper.
“It’s something you don’t really see in our industry,” said Cerny. “It’s usually for surgical instruments. But it works very well on stainless.”
With the support in place, the plates welded together, and the seams sanded down – the last step was applying a highly reflective polish. The substance used was a waxy substance called rouge
To achieve the gleaming, highly polished, reflective mirror finish, the finishers used a kind of jewelers’ polish, a waxy substance called a rouge. Three types of rouges contain three grades of abrasives.
“Everyone will tell you that if you skip a step, you have to go back,” said Cerny. “We had 24 or 25 people working at once just on the outside—we had to make sure all the steps were taken. We didn’t polish a 3-foot square all the way to mirror and then move over. We would do a certain step on large areas of the surface and then do the next step.”
After 5-plus years in the making, Cloud Gate was finally completed on August 28, 2005, and officially unveiled on May 15, 2006. The sculpture is seen by millions of people every year, all marveling at the odd shape and the mirror-like finish. It truly is a welding wonder brought to life for all to enjoy.