A longtime Hammco employee met owner Charles Helscel as he entered a 10,000-square-foot industrial warehouse sheltering tons of pipe, either already machined or waiting to be. Helscel chuckled as he heard that four semis full of pipe had been turned away that morning - for lack of space.

"That's how busy we are," he said. "All this you see here, all this is for projects already paid for."

Today's rising oil prices have created a roaring bull market for Owasso-based Hammco Air Coolers, maker of 80,000-pound heat exchangers for oil refineries and offshore oil rigs. But even as he prepares to build one 20,000-square-foot addition to his 90,000- square-foot complex, with plans for a second, 66-year-old Helscel approaches the surging business with caution. Having lived through the '80s oil bust, he vividly recalls what overextending operations can do.

"Business is growing faster than I've ever seen it," said the 36- year industry executive, who foresees his revenue approaching $30 million this year - up from $18 million-plus last year.

With a six-month backlog of contracts, Helscel refused to speculate on next year's revenue, noting he has already turned away deals that could force him to grow too quickly.

"I can do that when I know the economy is strong," he said with a smile. "We can be as big as we want to be with the volume of business that's out there.

"I have never been one to try and grow too fast," he added, "because it's difficult to get the quality of people that Hammco has."

While oil prices have driven the energy market, Helscel credits much of Hammco's growth to tougher Environmental Protection Agency regulations that spur refinery demand for his huge heat exchangers. This, along with refinery expansions planned to accommodate energy market growth, promise a long era of prosperity.

"They say we have 10 years of business like this in front of us," he said.

Building on garbage

Helscel entered the heat exchanger sector somewhat by default. Emerging from high school without the means to go to college, and not knowing exactly what he wanted to do, he found a job with a now- deceased manufacturer of heat exchangers. He soon decided that he needed a much stronger education if he was going to succeed in that field, so he attended night classes for two years as he pursued his office work, rising to the level of draftsman.

Moving to The Happy Co., another Tulsa-based manufacturer of heat exchangers, Helscel continued his night courses at Tulsa University. Through 13 years at Happy, Helscel rose through the ranks from chief draftsman to chief engineer to plant manager - the post he held in 1970 when Happy was bought out by an East Coast conglomerate. While his career continued its upward movement, he came to dislike how the new owners "treated people like a number."

For Helscel, the turning point came when he was invited to meet with company officials in Florida. Asked to become president of Happy, Helscel realized the move involved accepting business practices that conflicted with his religious beliefs as a member of the Assembly of God. So he turned down the promotion and, while remaining at Happy, opened a fabrication shop in a dairy barn east of Owasso.

"We were paying $50 a month rent," he said with a laugh, running the firm a night as he continued his day job at Happy. As its contracts grew - eventually to include not just Happy Co. but also competitors - Helscel built a second line of business selling containers for refuse haulers.

"They would put down a 10-percent down-payment and then pay 10 percent a month on the balance plus 1 percent interest," said Helscel.

That revenue stream grew to where Helscel found himself making money just from those "revolving charge accounts." It also led him to build a sister company, Commercial Containers Inc., to produce roll-off containers for the garbage trucks.

By January 1974, business demands left Helscel no time to spare for Happy. Still, it took six months before he could find his replacement and leave that firm, even as he established Hammco in a 20-by-60 building on five acres along the east side of U.S. Highway 169 in Owasso - where it remains to this day.

"I made a deal with the owner to buy the property for $300 a month for eight years," he said, "and I thought to myself, 'Lord, how am I ever going to pay this off?'"

Assembled through auctions

As the 1980s approached, Helscel decided to start offering his own line of heat exchangers, which would give Hammco control of its own destiny. The move proved beneficial as the '70s energy boom turned into the '80s energy bust.