Over lunch the other day, an official from the Soviet Embassy slipped me a document hot off the ticker of the Soviet news agency, Tass. Datelined Moscow, it was an account of an interview with Boris Shcherbina, the U.S.S.R. minister for building enterprises in the oil and gas industry.

"The pace of building the transcontinental pipeline has grown faster every day since the Soviet Union adopted additional measures to offset the U.S. administration's discriminatory actions," Shcherbina was saying. Arguing that the Russians aren't even going to need the British, French and Italian turbines that are the target of U.S. trade sanctions, he boasted:

"The pipeline will become operational on schedule. It will be equipped with turbines of the same capacity as planned before -- but now they will be of Soviet make."

A big bluff, eh? Partly. Some of what you pick up in the Soviet press these days about the Siberian pipeline to Europe has to be bombast for consumption abroad, or pep talk for consumption at home. But much of it is not.

Intelligence reports confirm what the Soviet press barrage suggests: as a point of pride and prestige, the Soviets are reallocating resources, accelerating work schedules, whipping up do-it-ourselves determination. "This is our answer to Ronald Reagan," reads a banner over a turbine factory in Leningrad -- the answer to the U.S. effort to block the participation of U.S. firms and their European subsidiary and licensees in the massive pipeline project.

Thus what began, in Ronald Reagan's eyes, as a matter of high principle, directed at Poland, is fast turning into an East-West test of will and technological skill. By that measure, even some high administration officials fear that the pipeline fiasco may well wind up for Ronald Reagan as some political-psychological-diplomatic combination of Jimmy Carter's Iranian crisis and John F. Kennedy's Bay of Pigs.

The administration sanctions may well succeed. The British, French and Italian governments are shouting about the sanctity of signed contracts and their own sovereignty. But the combined European effort is critically dependent on rotor blades manufactured by a French licensee of General Electric which is so far committed to only about one-third of the number needed. It's by no means certain that the French will compound their defiance of the Reagan administration by entering into new contracts to supply the balance.

If the result is greater Soviet self- reliance, this would certainly strain the already enfeebled Soviet economy by requiring reallocation of scarce resources. Soviet consumers would suffer to keep defense production going.

But against the damage to the Soviet economy must be weighed much more than merely the damage done to alliance relations or to the reputation of American business firms as reliable international traders. That might be bearable, if in the process the pipeline actually could be blocked or seriously delayed. But the odds are that the Soviets will find the means to complete it, for all practical purposes, on time.

To see where this would leave the Reagan administration, consider just two of the arguments for throttling the pipeline: that Europe would acquire a dangerous dependency on Soviet natural gas; that the Soviets would earn billions of dollars of hard currency annually by sales of the gas to Europe. Neither one holds up if the pipeline goes through.

So what's the point? The principle of the thing, apparently. Before the Versailles summit last June, Treasury Secretary Donald Regan told an on-the- record White House briefing emphatically that it was too late to stop the pipeline, and not worth the effort. Yet just recently, Regan was arguing that you had to try: "There are some things that override a free economy and that's called a free nation. . . . We have a definitely hostile threat from the Soviets."

What had turned the Treasury secretary around? A June 18 White House meeting when what might be called a moral majority of one, Ronald Reagan, overruled the departments of Treasury, Commerce and State. As one high- ranking and vigorous opponent of the president's turnabout sums it up: "We are demonstrating our strength of character by shooting ourselves in the foot."