One of Chicago’s most popular tourist attractions is the John G. Shedd Aquarium, found downtown on Lake Shore Drive. It is one-third of the Chicago Museum Campus that includes the Field Museum of Natural History and the Adler Planetarium. During the day, the Shedd Aquarium has two million museum visitors a year. In the evening, it hosts white tie charity events.
When the aquarium decided to expand its display area with the addition of a US$45 million dollar “Wild Reef” exhibit, it was not a project for the faint of heart. More than 30 sharks would be swimming above and around the visitors in a curved 400,000 gallon habitat in a building constructed over 75 years ago. Moreover, the Shedd Aquarium was built in a landfill area mere feet from the shore of a turbulent Lake Michigan. In winter, waves crashing against its foundation can reach a height of thirty feet. To construct a 27,000 ft2 addition it was necessary to extend the property further into the raging surf. A coffer dam was constructed, and twenty-five feet below street level, hundreds of steel I-beams were pounded into the earth until they struck bedrock.
The three-dimensional revolution
In the past, three-dimensional (3D) drawings were the exclusive purview of spacecraft engineers and luxury automobile designers. It was hard to justify the expense of mainframe capability and custom software except for the most demanding engineering applications. However, things have changed in the last decade. Engineering firms using AutoPLANT piping design software can accurately visualise a complete system, as complex as any refinery, in 3D accuracy. These drawings allow layout without the possibility of interference, along with temperature/flexibility and weight calculations, parts estimates, takeoffs, and links to detail drawings.
PDC Engineering, Inc. is a Chicago-based consulting firm that specializes in piping design. Contractors, end-users and larger engineering firms often hire PDC for their specialty skills. To begin the design process in this project, PDC determined the precise location of these pylons using a Leica laser system. This was necessary because maintaining the perfect uniformity of driven pilings is not an exact science. Yet the location of these load bearing pylons would be used to support the two-level structure containing the exhibits and all the process equipment. Floor-to-ceiling acrylic windows would allow visitors to view a total of twenty-six interconnected aquatic habitats containing a grand total of 750,000 gallons of sea water.
The pylon location information and two-dimensional (2D) architectural plans were superimposed and built into a 3D model, including piping design. Clicking on any tiny element of the final design pulls up drawings, specifications and complete details of individual components. More important, however, is the ability of 3D designs to completely eliminate any possibility of the structural interference of different systems. A set of 2D architectural drawings can be easily misread or misunderstood, concealing interference errors. 3D computer generated plans are virtually foolproof.
Safe piping design
Complex piping design and site installations have never been easy. Often the design elements are merely shown as schematics, with the installation details left up to the pipefitters and field superintendent. Union fitters often work from sketchy elements of architectural prints. The existing piping at chemical plants and refineries, and the lack of as-built drawings, had previously made piping design a haphazard event. In this case, a proven method provided definitive answers to complex 3D problems I with cost-savings.
Spool drawings - detailed drawings of smaller pipe elements - allow pipe sections to be pre-assembled and match-marked in a shop, then shipped to the job site for quick assembly. This feature alone has been proven to reduce installation costs by 50% in some cases. Shop prefabrication of piping spools can reduce on-site staff, field coordination and weather considerations. The Shedd Aquarium installers needed to field-fabricate only sixteen spools for final fit-up. Savings on field labour alone were US$80,000, and warming tents and wind breaks were largely eliminated.
High quality piping design, like that available from a consulting firm like PDC, can slash engineering costs, because these services are available on an as-needed basis. Fabrication costs can also be reduced, because the system is so accurate, almost all the pipe sections can be pre-fabricated in the shop. Installation costs can also be reduced, because pre-fabrication of over 95% of the pipe sections greatly simplifies and reduces on-site labour and supervision. 3-D views allow verification of all clearances and greatly facilitate construction meetings and quick understanding of the design.