Reports of the death of heavy metal in Napa have been greatly exaggerated.

While Napa Pipe ceased production three months ago, next door, in a former Kaiser Steel fabrication plant, Trans Bay Steel Corp. continues to turn out orders that dwarf their human creators.

Inside buildings big enough to house a fleet of Goodyear blimps, the crew at Trans Bay cranks out structural supports and pilings for the new Bay Bridge.

Business is so good that Trans Bay wants to double its work force to 100 by year's end.

Trans Bay has the brawn of a big-time steel fabricator, yet the community is largely unaware of its existence. In Napa, big steel creates less of a ripple than the latest boutique winery.

During the day, sirens at the plant let loose a blood-curdling scream. Stand back, they warn. A crane hoisting a 100,000-pound bridge support is moving over the construction floor.

Trans Bay is a place of industrial superlatives. It has the largest steel lathe on the West Coast, equipment that can bend a 6-inch plate of cold steel into a circle and the crane capacity to lift almost half a million pounds.

The Bay Area was once ringed with heavy steel fabricators such as this. They built the bridges, refineries, tunnels and pipelines essential to California's infrastructure, said Bill Kavicky, a Trans Bay owner.

Not today.

This industrial capability has nearly disappeared. Two major exceptions are Trans Bay in Napa and XKT Engineering on Mare Island -- both started by former Kaiser Steel employees after Kaiser folded in 1987.

"If this place ever disappeared for any reason, you'd never be able to put it back together," Kavicky said. Not in the Bay Area, where prime water-front real estate tends toward offices or houses.

Trans Bay rents five acres under roof from Oregon Steel Mills. Kavicky's office is in the oldest structure, a steel-framed building dating from 1941 when Basalt Rock began to build a wartime shipyard.

Inside the plant, plates of steel thicker than a Quizno's sub are being carved by computer-guided torches. Sparks fly as welders practice their craft on steel fabrications far bigger than the trucks they drove to work in.

"You don't walk into too many places like this," Kavicky said. Not in the Napa Valley. Not anywhere.

Workers at Trans Bay gripe that their expertise goes unrecognized. "Napa doesn't even know we exist. We don't make noise. We're not high profile," said Bill Kroplin, a Trans Bay owner.

"Not even our own families understand what we do," Kroplin said. "Even my wife has no idea of what we're fabricating down here."

Will Tallman, a Trans Bay employee who began with Kaiser Steel in 1956, remembers when Kaiser fabricated steel on a heroic scale.

He was part of projects involving nuclear submarines, missile systems and the space shuttle. "You look back at some of the things we did over the years ... you think, 'How did I get involved in all that?'" Tallman said.

Kavicky argues that the Oregon Steel facilities behind Napa Valley Corporate Park are part of an industrial infrastructure too important to toss away.

The Napa River was straightened and dredged to accommodate the towering steel structures that left Kaiser Steel by barge. Similarly, bridges between Napa and San Pablo Bay -- Highway 29's Butler Bridge, the Brazos railroad bridge, the spans at Highway 37 and Mare Island causeway -- were built larger than necessary to meet Kaiser's specifications.

"A lot of people have forgotten about that," Kavicky said.

Steel fabricators in the Bay Area struggle to stay in business, said Al Bottini, president of XKT Engineering in Vallejo. Recent years have been good ones because of all the bridge retrofit work, but those projects are winding down, he said.

With the Bay Area's high wages and California's high workers' compensation rates, it's difficult for a local fabricator to compete against foreign and out-of-state companies, Bottini said.

Trans Bay sees many strong years ahead, particularly if it wins the business that it expects when the major span of the new Bay Bridge is rebid.

Oregon Steel knows that Trans Bay would like to buy its leased facilities if Oregon Steel decides not to resume making pipe in Napa, Kavicky said.

"We can be a mainstay for the future of this community," Kavicky said. "It's not a dead place. It's still a phoenix."