Welding Wonders

Welding Wonder: Epcot’s Spaceship Earth

“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.

Epcot Construction

Construction of the iconic geosphere took 26 months.

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.

Sphere structure, ride and show structure, and utility structure as seen through the north-south section of the sphere. Courtesy of Simpson Cumpertz and Heger.

Sphere structure, ride and show structure, and utility structure as seen through the north-south section of the sphere. Courtesy of Simpson Cumpertz and

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.”

Disney contracted MIT to conduct wind tunnel tests on a 1/16” = 1’ scale model of the attraction.

When the aluminum exterior panels were installed, erection was started from the roof and worked down.

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.

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