Five veteran union welders told the Senate Labor Committee yesterday that the nation's welders buy their way into jobs on everything from bridges to nuclear power plants by paying officials of the Boilermakers Union as much as $2,300 for a union membership that routinely costs no more than $100.

The welders, three of whom testified from behind an opaque glass screen to hide their identities, told the committee that skilled welders routinely take welding tests on the job in order to qualify unskilled welders for difficult construction projects. The welders agreed that fees paid to qualified welders for faking the tests range from $20 to $100.

"I took 30 tests in two years at one nuclear plant site, most of them for other welders," one of the three unidentified welders testified. "In all that time, I never saw an inspector or a representative of the Nuclear Regulatory Commission" checking on the workers taking welding tests, he said.

Another of the three unidentified men testified that he knew of welders who paid $1,200 to $1,600 for their "union books" rather than go through four years of apprenticeship training that would get them union cards for $35 to $50. This welder told of one man paying $2,300 to a union official in Montreal for a membership that qualified him for welding work anywhere in North America.

"If that gets you a job where you make $17 to $19 an hour," the welder said, "that's a small investment to make to guarantee that kind of work."

So rampant is the practice of buying union membership, the third unidentified man testified, that his local more than doubled, to 1,400, in a year when only 40 members were training as apprentices.

Brothers Gary and Wayne Boring of Indiana, Pa., who did not hide behind the screen, testified that they knew of 35 to 40 welders who worked on construction of the Three Mile Island nuclear plant and had other welders take their onsite tests.

The Borings said they reported the practice to the Labor Department, then the Justice Department Strike Force on Crime and finally the NRC, which asked for the names of the welders so that they could be interviewed.

"We were told by the strike force not to give the names to the NRC," Gary Boring said, "because they did not want the investigations to overlap."

All five witnesses told the committee that Boilermakers Union members are regularly forced to buy raffle tickets to keep their jobs. The five called the tickets "50-50" tickets because sales proceeds are supposed to be split between the member whose ticket is drawn at the raffle and a "sick and disabled" fund for unemployed welders burned on the job.

"I don't know what happens to the raffle money, but it's well known that if you don't buy the tickets you won't be on the job long," one of the unidentified welders testified.

Of the hearings' purpose, Chairman Orrin G. Hatch (R-Utah) said: "Whenever this committee follows the trail to the Justice Department and the FBI, we are stonewalled by bureaucrats who place prevention of embarrassment of the agency ahead of the public interest. How often does this committee have to showcase such situations before the federal agencies begin to move?"