Nov. 8--When 62 pipe and steel workers at Precision Tube Co. in North Wales walked off the job Aug. 7, the economy had just dropped 274,000 jobs. Unemployment was nearing 10 percent, and almost 14.5 million people were out of work.

"I know it sounds crazy to go out on strike during a recession," said Donna Ulrich, unit president of United Steelworkers of America Local 6816-01. "It was really scary, because I knew there were no jobs out there."

Striking during a recession? Is it crazy?

That depends, experts say, on the financial health of the business, the skill of the workers, the availability of qualified replacements, and, in large part, whether the union represents public- or private-sector employees.

Ulrich's steelworkers, out until Sept. 21, probably faced greater risks than Local 234 of the Transport Workers Union, which sent 5,100 SEPTA drivers and operators out on strike Tuesday.

None of Ulrich's members crossed the picket line. But Precision Tube, which did not return several calls for comment, hired temporary workers who did.

Hiring replacements is rare in the public sector.

"I can't think of a single situation where workers were permanently replaced on the public sector," said Gordon Pavy, national collective-bargaining director for the AFL-CIO in Washington.

There is a notable exception, and it made labor history.

In 1981, when members of the Professional Air Traffic Controllers Organization walked out, President Ronald Reagan replaced nearly all of them, breaking the union.

"I think a public employer would be hard-pressed to do that," Pavy said. "We like to think of our government agencies and quasi-government agencies as being more fair-minded than private employers who are out for a profit."

That gives public-sector unions an unfair advantage, said Chris Edwards, an economist for the conservative Cato Institute in Washington.

"There is no downside for public-sector unions to push too far because they always have their jobs," he said.

"With private-sector unionism, there is a tug and pull between employer and employee," Edwards said. "There is an economic struggle.

"Public-sector unions have government officials in a tight spot. It's not their money they are playing with."

In 2008, 12 percent of all employees were members of unions. In the private sector, the percentage was 8, but in the public sector, more than a third of employees, 37 percent, were in unions.