Mastering Demanding Ductwork

(ALL PHOTOS): Extra durable, 11-gauge steel duct was used to endure the continuous effect of sandblasting, which results from asphalt production. 

David MacDonald, project manager for Black & McDonald in Scarborough, Ontario, has extensive experience with industrial air handling systems, including removing explosive dust from woodworking facilities. 

But a recent industrial project presented him with a challenge he’d never faced before. “We built a fire suppression system inside the fume collection ductwork for this job,” MacDonald says. “The ducts are not explosion-proof, but there’s a potential buildup of tar, which can catch fire. We tapped holes every 10 feet and inserted sprinkler heads inside the ductwork.” The unique system prevents the tar from burning through the duct from the inside out.

IKO Industries Ltd. manufactures asphalt shingles in Canada, the U.S., and Europe. When it was time to enlarge their major Brampton, Ontario plant, IKO trusted Black and McDonald’s wholly owned subsidiary, Roberts Onsite, with the millwrighting and mechanical needs for the entire expansion. Roberts Onsite then subcontracted the air movement parts of the contract to Black & McDonald because of their specialized experience with ductwork. The facility includes three air systems, the base building system for heating and cooling, the dust collection system to control granular dust, and the fume collection system to remove chemical fumes from the workspace.

Besides the need to prevent tar fires inside the ducts, Black & McDonald also prepared the system for the destructive action of sand flowing through the ductwork. “Asphalt shingles are topped with a sand-like material, so the dust collection and air movement systems have to be corrosion resistant,” MacDonald explains. “Just imagine the effects of sandpaper going through the duct at all times.” 

Black & McDonald provided extra-durable duct in 11-guage steel to compensate for the equivalent of continuous sandblasting. The sheer size and the mass of the material presented installation challenges. “With all of the duct being 11-gauge steel,” MacDonald says. “The most unique challenge was getting the very large diameter, heavy gauge duct routed though many interferences to make it look good and function as required.”

Each angle was reinforced with quarter inch plate steel, but even plate steel can’t stand up to sand forever. “Every time the dust collection ductwork takes any kind of turn, the outside part of the elbow has to be removable so it can be replaced before it wears out,” MacDonald says. Black and MacDonald installed flatback elbows throughout the plant. “We don’t use these every day. My foreman only used these in one previous project, and he’s been around for 30 plus years. The back part of the elbow is a flat piece of metal that you can unbolt while the inner part of the elbow stays in place. When it’s worn, you simply unbolt and replace that back plate.” 

The Brampton, Ontario IKO plant is three stories high with two giant five-story silos behind the building that carry the asphalt material. Black & McDonald installed about 65,000 pounds of round ductwork in the $100 million, 200,000 square foot facility. 

Because the client already had a functioning asphalt shingle manufacturing facility, the project was briefly delayed as a Covid precaution. With delays, the project took over a year to complete, adding that Black & McDonald used some of their most experienced personnel for this demanding, one-off project. “The timeline wasn’t condensed down, so we didn’t have a big crew,” MacDonald explains. “The field team maxed out at four, and a full-time welder and a full-time fabricator worked at the project every day in our shop. We had a small CAD/BIM crew of two and two indirect team members, a project coordinator and me.” 

IKO’s inhouse team designed the systems, and Black & McDonald fabricated all components and duct inhouse. “We pulled the information off the plan IKO provided us, then used SMACNA Industrial Standards and our AutoCAD/BIM team to generate spools,” MacDonald says. “These detailed sections of the ductwork contained all the information we needed. We would send a spool off to the shop, and they built a piece to the correct specifications.”

Black & McDonald used the newest technology to design and coordinate the work. “We have all kinds of different software systems,” MacDonald says. “We used Procore for the construction management side of things and AutoCAD and Revit modeling with Trimble for the design. The computer team tells me what we need, gives me the information, and we decipher and build it.” 

This is a huge change from the days when his crew would work problems out on paper, but MacDonald was pleased with the results they were able to deliver. “It worked out really well. We had a super good team on that job.”