Copper piping resolves fabrication challenge for children’s hospital
By Andy G. Kireta Jr.
Hospitals can be scary places for both children and families. In efforts to be the exception, the Nemours/Alfred I. duPont Hospital for Children in Wilmington, Delaware — one of the best rated children’s hospitals in the nation by U.S. News and World Report — recently underwent a $215 million expansion as a way of increasing its appeal to families.
The 500,000-square-foot expansion included two leafshaped wings, designed to look like the inside of a turning kaleidoscope, featuring a five-story atrium with a 144-bed building, private rooms and sleeping accommodations for parents, a new emergency department, and retail and dining facilities. The building’s unique curvature, while visually engaging, presented unforeseen challenges for the contractor.
The pipes won’t bend
The semi-circular, high-ceiling design of the expansion required a lightweight, malleable material for its large-diameter piping system that needed to perform roughly a six degree radius around the building while still maintaining its durability. Black steel pipe — the material originally specified for the project — did not meet the criteria and was proving to be difficult for the job.
According to Michael Duffy, the project manager for Binsky Snyder Mechanical Contractors, the installation team performed tests off-site in a pre-fabrication facility prior to construction. It was there that they determined that black steel would not be suitable for the project. He said that if the installation team had proceeded with steel, a significant amount of fittings would have been needed adding to the potential for leaks down the road.
An engineer on the project requested information from the Copper Development Association (CDA) in regards to bending copper tube in sizes up to 2 ½ and 4 inches. He was looking for a material that could wrap around the two leaf-shaped additions. Following discussions with the engineer and the installing mechanical contractor, it was determined that the minimal amount of bend required would be well within the limits for copper tube and could easily be accomplished by several local pipe bending companies.
“The copper is a lot easier to work with; you cut it, you ream it, you make the connection with pro-press or brazing and you move on,” said John Dimaio, general foreman at Binsky Snyder Mechanical Contractors.
The metal’s performance, versatility, resistance to corrosion and light weight, as well as its ease for bending and fabrication, ultimately made it the preferred option for the domestic hot and cold water service, HVAC systems as well as for medical gas distribution for this project.
“We have to perform, roughly, a six degree radius, due to the design of the building and we could not do that with any other product besides copper. We’re able to bend this product to where we need it to,” said Marty Corrado, project executive/prefabrication manager at Skanska USA Building, Inc.
“The buildings that we usually work in are rectangular or square, and you measure off columns, and you lay things out on the floor or ceiling to get your measurements, and put your hangers in,” Dimaio said.
The plumbing modules were prefabricated in a warehouse 10 miles away from the hospital. The modules included a large piping loop that runs around the outside of the patient rooms, followed by a more standard plumbing layout, a main outer loop that supplies the domestic hot and cold water. Also, in a patient’s room there is an inner loop for the staff and nurses’ sinks.
“[Copper is] the only product, to my knowledge, that we can run through a plenum ceiling,” Corrado said. “It also meets all of the NFPA requirements we need for penetrations one-hour, two-hour, three-hour, four-hour walls that are required for fire escape chambers in most buildings.”
Duffy said that prefabrication allowed the team to work in smaller crews and allowed them to keep up with the fast-paced construction schedule, especially considering that the large pipe had to be sent to a bending company so that it could wrap around the leaf-shaped additions.
Copper’s workability cut installation time and reduced labor cost all while adding to system integrity. Tubes and fitting were easily joined by soldering, press-connect and brazing.
Soldering is the most common method of joining copper piping systems with the widest range of fitting types and components, offering long-lasting, leak-free joints in systems operating to temperatures up to 250 F. Today’s solder joints are lead-free, and while they require heat to make the joint, they can be made with a standard torch or with flameless heating methods.
Brazing is similar to soldering, utilizes all of the same fittings and components, but is accomplished with a different joining material that melts at a higher temperature than solders. Brazing is typically used for systems operating at higher temperatures (up to 350 F) and pressures; where excessive vibration or other stresses are expected (HVACR equipment and systems, compressed air systems); and is the preferred and required joining method for medical gas piping.
Press-connect joining is the new kid on the block of copper joining. This mechanical joining method utilizes special fittings containing a gasket seal that are mechanically compressed onto the exterior tube surface, providing a durable, long-lasting, leak-free joint that can be made quickly with no heat or flame. Press-connect joining has steadily begun to replace the use of soldered joints in many systems due to its speed and ease of installation, which translates into reliable copper systems at reduced costs.
All of these joining methods were used on the Nemours/Alfred I. duPont project, each being selected to maximize performance while minimizing installation time and system cost. No matter which joint type was used, Binsky Snyder followed the recommended practices for making all of these joints outlined in the CDA Copper Tube Handbook.
In order to continue to provide exceptional care, the hospital — which has been in operation for over 75 years — also installed copper piping behind the walls and above ceilings to supply critical medical gases.
“Copper is largely the industry standard in the health care construction industry in the U.S. for many reasons. It is antimicrobial for one, and it has just been proven to be the best product to use for life support systems that are inherent in a hospital facility,” Corrado said.
One of the advantages of copper over other materials is that it does not burn. Its comparatively high-melting point (1981 F) makes it much less likely to spread flames or smoke throughout the building.
Medical gas installation
Copper in medical gas systems is joined to fittings and components by brazing, a process that requires heating the components being joined to temperatures in excess of 840 F (usually in the range of 1,200-1,550 F) and adding a brazing filler metal to the joint. To ensure the tube and components remain clean and free of oxides on the inner surfaces of the tube during and after brazing, an inert gas “purge” is required during the entire installation process of the system. During this installation and brazing process, a high potential exists to render the specially cleaned tube no longer suitable for service.
Several factors can contribute to contamination:
- Failure to purge, or purge correctly
- Loss of purge gas during brazing
- Failure to continue to purge until the system is cool
- Failure to protect open ends and unbrazed joints in the system until the system is completed
Once the system is installed and reaches the point of final verification testing, there is virtually no way of identifying how or why an odor may have been created within the system. Therefore, the following steps should be followed.
Use only ASTM B819 copper tube and wrought copper fittings that have been cleaned and delivered in accordance with the NFPA 99 requirements.
Inspect all tube, fittings and components upon delivery and throughout installation to ensure ends/openings remain sealed to protect the internal cleanliness of the components.
During initial installation, visually inspect the internal surfaces of the tube and fittings to ensure cleanliness and that protective tube plugs have been removed.
When the tube, fitting or component is installed — and prior to fabricating the brazed joints — tape or seal all joints and open ends to ensure that oxygen (ambient air) or other contaminates are not drawn into the system.
Use only oil-free dry nitrogen NF, intended for use as a medical gas during all testing and installation. Nitrogen supplied for medical purposes is created using equipment and processes to ensure it is clean, dry and oil-free. It is stored and transported in cylinders and containers that are cleaned to maintain the purity of the gas. Nitrogen not processed, stored and transported in this manner may contain trace amounts of medically unacceptable impurities that can deposit on the interior surfaces of the piping system and create odors in the system.
An award-winning hospital
Since its completion, the hospital has received numerous awards for its exceptional quality and patient safety. The use of copper allowed for the unique curvature of the design to become a reality and allowed the hospital to become a welcoming environment for both children and families.
To view the video showcasing the plumbing installation project at the Nemours/Alfred I. duPont Hospital for Children, visit www.youtube.com/watch?v=RSn18st-ylQ.
Andrew G. Kireta Jr. is the vice president of the Copper Development Association Inc. (CDA). Kireta is responsible for the use of copper and copper alloy systems and products in building construction applications, including plumbing, mechanical and architectural systems.