Caterpillar Tractor Co. has received a license to export 200 machines used for laying oil and gas pipelines to the Soviet Union, the Commerce Department announced yesterday.

Commerce Secretary Philip M. Klutznick approved the license for the $79 million worth of equipment after consulting with top officials at the State, Defense and Energy departments.

Caterpillar does not have a contract for delivery of the machines, which hold pipe sections while they are welded and wrapped and put into the ground, but needed the license before the Soviet would allow the company to enter a bid. The contract probably will be let before the end of the year, officials said. The equipment will be used to construct a natural gas pipeline linking fields in western Siberia with Western Europe.

Klutznick said approval of the license is in line with a policy established two years ago on exports of oil and gas-related equipment to the Soviet Union and reaffirmed after the Soviet invasion of Afghanistan. That policy presumes approval of licenses for exports of "end-use" equipment and disapproval if industrial technology for the production of oil and gas equipment is involved. The pipelayers constitute "end-use" equipment and "are freely available from non-U.S. sources," he said.

However, a State Department spokesman said the decision to allow export of the equipment was made at what he called "a very high level."