3D Model of Refrigeration System Permits Prefabrication, Cuts Piping Time by 30%

When Shambaugh & Son sets out to complete a project on time, it is a guarantee. Recently, by modeling a refrigeration system in 3D, Shambaugh was able to prefabricate most of the piping, reducing on-site construction time by 30 percent. This was also accompanied by significantly reduced installation costs. The refrigeration system was done for Hanson Cold Storage, a Benton Harbor, Michigan-based company with nine plants and almost 33 million cubic feet of refrigerated and general merchandise warehouse space. Shambaugh was awarded the $2 million refrigeration expansion for a Hanson Cold Storage warehouse in Lafayette, Indiana. The existing ammonia refrigeration system had been installed many years ago and suffered from numerous failures. Shambaugh's role involved the addition of three new freezers as well as the complete replacement of the existing refrigeration system with a new 912-ton ammonia system incorporating the latest technologies. The overall scope of the design included: a new refrigeration compressor room, three 350 horsepower and two 250 horsepower compressors, three, new, 30,000 square foot –20 degree freezers, 28 evaporators (coolers and freezers), and new refrigeration equipment and piping for existing freezers, coolers, and docks totaling more than 200,000 square feet of refrigerated space.

Meeting a Fast-Track Schedule

For this large refrigeration system, the scheduled construction time was very aggressive. "Because Hanson had committed the use of the new freezers and docks to customers, they hired a general contractor who gave us a very tight time frame to complete our work," says Tom Aurich, Senior Project Engineer at Shambaugh & Son. "We wouldn't have made it if we had done the design work in 2D."

When a system like the Hanson project is designed using traditional 2D drawings, one of the challenges is the complexity of the piping. In this case, most of the piping was on the roof of the building to keep the refrigerant away from the product and to allow for the easy service of the control valves. Pipes traveled down through the roof to connect with the evaporators on the plant floor. Laying out the piping in 2D, a designer would have had to indicate the elevations with 90-degree elbow (fittings) symbols, visualizing the third dimension in his head each time he started a new view. This aspect of the project alone could have been time consuming enough for Shambaugh to miss its deadlines.

After a 2D piping layout is done, additional plan, elevation, and isometric drawings are needed to convey the layout to the construction team. Each of these drawings must be created from scratch. This can be one of the lengthiest aspects of a project; construction can't start until it is done. Another drawback to doing a project such as this in 2D is that it is very difficult to detect interferences or other problems. When a length of pipe continues from one drawing to another, for example, the elevations on both drawings must match. If there is a mismatch and it isn't caught until construction, it could delay the project by requiring rework in the field. Finally, when a design is done in 2D, the construction process generally follows the conventional "stick build" approach. "Construction materials would have been delivered to the site in random lengths, then a site crew would have had to cut the pipe and installed it piece by piece," explains Aurich. "It's a much slower approach. You can't pre-weld or pre-bundle pipes unless you are very confident in your design."

Benefits of 3D Design

Recognizing the limits of the 2D design approach, Shambaugh converted to 3D designs on large projects 10 years ago. Shambaugh uses the 3D plant-modeling program, AutoPLANT from Rebis, Walnut Creek, California. This is an add-on to AutoCAD that creates "intelligent" plant models containing both the 3D geometry of the facility and textual information such as specifications. "We have stayed with this program because Rebis continues to enhance it with state-of-the-art CAD, database, and visualization technologies," says Aurich. Shambaugh uses many of the AutoPLANT modules including Piping, Structural Steel, Equipment, the automatic isometric generator, and a module that creates P&IDs.

With the AutoPLANT software, the Shambaugh engineer and piping designer created a 3D model of the refrigeration system, showing all of the piping, equipment, pipe supports and structural steel. The model was thoroughly checked for interferences by rotating and viewing it from all angles. When the digital model was clash free, they felt confident enough to begin assembling pipe in their fabrication facility. "If we had erected the pipe piece by piece at the site, it would have taken six months," says Aurich. "The head start we got through prefabrication allowed us to complete the major portion of the construction in only three months and meet the owner's demanding schedule."

The design team began creating the digital plant model by placing equipment in 3D space. A piping designer used the AutoPLANT equipment module to create 3D models of components such as compressors, freezers, coolers, and so on. "They didn't go into great detail," says Aurich. "All we really needed were overall dimensions and nozzle locations." The next step was designing and locating the 75 major pipe supports that were needed on the roof of the building. The contractor had given Shambaugh 2D drawings showing the location of the structural steel. Senior piping designer, Roby Geiger, added the grid to the AutoPLANT model of the system, helping to see where to attach the supports.

When that was done, Geiger began routing pipe. Working in 3D, verses 2D, allowed him to view the impact of his work immediately, rather than flipping through 2D drawings and trying to follow the entire line. "The 3D makes the piping layout real," he says. "It also goes faster than working in 2D." This layout had approximately 150 lines. Geiger estimates that if he had done the work on 2D drawings it would have taken twice as long as it did with AutoPLANT. Due to his past experience as a pipe fitter, he knew where it would be difficult to have pipes meet exactly. "I built allowances for that into the model," Geiger explains. "I left an extra six inches of trim where I knew there might be problems."

Project Completion

While the design was in progress, the Shambaugh engineers would periodically rotate the model to view their work from different angles. This let them spot interferences and fix them in the software, reducing the likelihood that a problem would show up during construction and cause delays. Once the model was free of errors, the next step was the production of construction drawings. Rather than creating section and plan views by hand one at a time, Geiger and his colleagues picked the desired views of the 3D model and used the software's tools to spin off drawings automatically. This eliminated hundreds of hours of drafting time. Piping isometrics were created in a similar manner using AutoPLANT's automatic isometric generator. This module created ISOs with elevations and dimensions tagged and located, with materials for purchasing automatically derived from AutoPLANT’s database.

Shambaugh began assembling the piping for the new portion of the facility while the contractor was pouring the footings. "At least sixty percent of the welds were done before we hit the site," says Aurich. As soon as the roof of the building was finished, Shambaugh started bringing up the prewelded pipe pieces by crane. "In addition to being ready to assemble the minute the building was done, another benefit of having done so much prefabrication is that we were able to reduce material handling costs by nearly 40%," explains Aurich. "Instead of taking bare lengths up and hauling the waste down, the only scrap we had was the trim. And because we had assembled 40-foot lengths instead of 20-foot random pieces, we needed less picks with the crane." The portion of the assembly that had to be done on the roof was completed in three months. In the entire construction process, there were no delays caused by errors in the design or prefabrication.

While the on-site work was being done, Hanson continued to operate using the existing refrigeration system. As soon as the new system was ready, the plant was switched over to it. Then Shambaugh removed the old equipment from the existing facility and performed the necessary renovations. This phase took six weeks. There was not a moment when the plant was completely shut down. "Hanson was extremely happy because we were able to keep them in operation while we put the new system together. They also benefited from having the revenue stream from the new system coming in sooner," says Aurich.

The new refrigeration system has performed flawlessly for two years. But Hanson is not the only one who is pleased. Shambaugh considers this one of its most successful projects. "It was a large job, we did a great deal of prefabrication, and everything went together perfectly," Aurich says. "AutoPLANT 3D modeling is a big part of why it went so well. It enabled us to work quickly and create a very accurate design"

About Shambaugh & Son

Shambaugh & Son, a division of Comfort Systems, USA, is a nationally recognized construction-engineering firm specializing in design/build and fast-track project delivery. In business for 75 years, the 1,500-person firm has offices in Fort Wayne, Indianapolis, Lafayette, and South Bend, Indiana; Detroit and Kalamazoo, Michigan; Chicago, Illinois; Toledo, Ohio, and Livermore, California. The company has worked in more than 40 states and six foreign countries. It is currently the largest contractor of its type in Indiana and ranked the third largest specialty contractor in the United States. Shambaugh & Son handles the full range of new and retrofit construction for industrial, food, pharmaceutical, commercial, and institutional projects, completing approximately $260 million total volume per year, including projects from $2,000 to $40 million. Nearly 70 percent of its work is the Design/Build, negotiated type on a "single-source," turnkey basis. Shambaugh is staffed with 110, in-house engineers who specialize in Mechanical, Electrical, Process, Refrigeration, Process and Temperature Controls, Fire Protection, and Material Handling/Packaging Systems! Their automated prefabrication facility plays a crucial role in their success in reducing project costs, meeting accelerated schedules and assuring quality control. Shambaugh & Son has been national recognized with 3 coveted U.S. Food Plant of the Year awards, National Contractor of the Year, and numerous safety, productivity, project and quality assurance awards.

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