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Twice a day, Mike Clark drives past Tinker Air Force Base in Oklahoma City as he goes to and from his job at Matherly Mechanical Contractors LLC. 

The sprawling base has been a part of the city for so long that many commuters may not pay much attention. But Clark always notices. That’s because, for Clark, the 66-year-old vice president of operations at Matherly, Tinker AFB isn’t just a bunch of military planes and hangars. It’s been an important Matherly client for a long time. 

“They know us,” Clark says. “They know our work.”

Many area companies could say the same about Matherly Mechanical. It was founded by Jack Matherly in 1962. With an initial headcount of just four workers, today the third-generation industrial and commercial HVAC, architectural, plumbing, pipefitting and fabrication company has 200 employees and is one of the larger sheet metal contractors in Oklahoma. 

Since the 1960s, Matherly has fabricated and installed numerous HVAC systems and components at Tinker, which has long been the site of military aircraft maintenance, repair and refurbishment projects.

Tinker Air Force Base dates to 1941, when it was established as the Midwest Air Depot. It was the site of a Douglas Aircraft Co. factory, producing military transport aircraft during World War II. Workers at an on-site industrial plant repaired B-24 and B-17 bombers. In 1942, it was renamed Tinker Field after Clarence L. Tinker, the first Native American U.S. Army major general. Following the founding of the Air Force in 1947, it became a U.S. Air Force Base. 

Today, Tinker is a major force in Oklahoma’s economy, with an estimated annual impact of over $3.5 billion, according to government officials. Located just five miles from downtown Oklahoma City, it encompasses 5,000 acres and has more than 700 buildings. The largest single-site employer in the state, more than 26,000 people (military and civilian) work at the base. The Navy and Department of Defense also have major presences there. 

Matherly’s most recent work at the base was a $3-million ventilation project at a hangar at the base’s southeast corner. The sheet metal contractor was hired to replace four 100,000-cfm blowers; fabricate and install large, round, industrial exhaust ductwork; and install a new filter bank. The ventilation upgrades were needed because the hangar is used for aircraft stripping and repainting, which can generate toxic fumes. Ventilation is critical. 

“It has to have full-blown ventilation, plus the hangar’s cross flow ventilation,” Clark says. “It's push-pull ventilation. So one side's bringing the air, and they're kind of bringing it up high, probably 30 to 40 feet. Then it cross flows down to the filters on the ground.”

And those filters are large, Clark added: (350) three-stage, 24-by-24 inches. They feed into large, ducted exhaust plenums outside the hangar. The ductwork was all negative 10-inch static pressure, made of 12-gauge metal. Discharge duct was mostly 70-inch round, but some went up to 84 inches, Clark says. 

The 100,000-cfm fans Matherly installed had 5.5-inch external static pressure and 150-horsepower motors. Each weighed up to 15,000 pounds, driven by variable frequency and variable speed drives. Matherly workers also rebuilt an existing plenum at the hangar. 

The ductwork — all 35,000 pounds — was manufactured at Matherly’s sheet metal shop, located about 1.5 miles from the base. Fabrication took approximately 3,100 hours, plus another 200 hours for drafting work in the shop. Eight workers were assigned to the project.

Installation required extensive coordination, Clark says. 

“It was all done by airlift and crane because it’s too big,” he says. “There was nothing you could install by hand on this.”

Pressure testing was also required. The duct had to tie into the existing plenum and bracing was necessary.

“Because we went from 6-inch, negative 10, we had to put these braces on 20-inch centers,” Clark says. “They were four-by-four hat channels. Those all had to be attached to the existing plenum. Then we had to pressure test all that to make sure that when we fasten all those channels and the seams that we met the �鶹��� duct air leakage testing standards.”

Altogether, field installation took around 8,000 hours. 

Clark says he likes working on projects at the base, although Air Force work isn’t for everyone, he adds. They’re demanding clients and don’t tolerate delays. 

“It’s a tough place to work,” he says. “Air Force officials are there every single day. The standards are tougher, more stringent. This is not a job for the weak to take on because of the size of it. They can't be down for too long because the Air Force has to be cranking those planes out constantly. We didn't have a whole heck of a lot of time to do it. It all had to be prefabbed, and we had to design it to where it all fit in place perfectly.”

But that kind of scrutiny doesn’t bother Clark. 

“We had no issues on this job,” he says. And unlike some projects where owners can be slow to pay — dragging it out for 60, 90 or more than 120 days — the Air Force pays promptly. “They usually pay in approximately 30 days.”