The natural gas industry and the General Accounting Office are exchanging invectives over a GAO report critical of liguid gas safety, two months before the report is to be published.

The 800-page safety study by Congress's investigative arm is one of several items the liquid gas industry thinks is threatening its survival before it is even properly born. An estimated $20 billion in plans and proposals to import liquefied natural natural gas (LNG) are just about to get off the ground. And the industry fears this study could produce that most fearsome of beasts, an aroused Congress.

In addition, the Dpartment of Energy appears more and more to favor a pricing system the industry vows will mean ruin. Environmentalists oppose many proposed import terminal sites, and labor problems have delayed start of major deliveries to the first big terminal - at Cone Point, Md. - by several months.

It led to an unusual press conference this week at which industry executives ignited a small cloud of liquefied natural gas (LNG) before a startled crowd of reporters in order to refute the still-secret GAO safety study.

"No! No!" cried one reporter in the front row as the match was applied . A plume of flame lit the room briefly and went out, according to those present. That, the executives said, demonstrated that fears of a massive fireball resulting from an LNG spill were groundless.

Chapter of the report have been circulating to companies mentioned in them for months, while government agencies received the report draft for comment last week. "We sent it to everybody and his brother. If we're wrong they should be able t prove it," said GAO author David Rosenbaum. He hopes to have it out by April 1.

LNG is regular cooking gas chilled to 260 degress below zero Fahrenheit, at which point it becomes a liquid that this is 1/600th the volume of the gas and is therefore economical to transport. If it should spill, the liquid rapidly vaporizes into a gas which, mixed with air, is highly flammable.

The conclusions and recommendations section of the GAO study, a copy of which was obtained by The Washington Post, call the prospect of such s spill in a big city, "very frightening."

The study examined liquefied propane, methane and naphtha, calling the first two lequefied energy gases (LEG). "In most situations, for a given volume, LPG (propane) is more dangerous than LNG (methane), and LNG is more dangerous than naphtha," the study said.

The GAO attacked industry safety conditions on seven broad fronts and the industry responded point-by-point at the press conference and in private comments.

Sabotage: "The requirements for security . . . are so slight as to provide virtually a deterrent to potential sabofeurs," the report said. It described situations in which mines, bombs, hijacked vehicles and arsen would produce a "catastrophic situation."

The American Gas Association said the study "is obsessed with the concept of sabotage." The threat to gasoline, ammonia, chlorine and other energy facilities is just as great as it is for LEG, it said.

"It's the most irresponsible thing I've ever seen," said Columbia Gas System Inc. spokesman Max Levy when the report began to circulate last autumn."It tells you how to blow up an LNG terminal complete with a bibliography on how to make the bomb . . . how secure is 'secure,' anyway?"

Storage facilities: Tanks holding LNG are built with small safety margins and "it is likely some of them will fail" in earthquakes, winds, or floods, the study said. The fluid is then likely to wash over the retaining dikes now required, many of which are weaker or smaller than they should be.

The American Gas Association said tanks and dikes are built to meet or exceed existing standards and the probability of their failure is no greater than it is a bridge or a building.

Transportation: Coast Guard personnel responsible for shepherding LNG tankers have inadequate training and plans have not been drawn up for coping with a spill either from a ship or from trucks on land, the GAO report said. "It would be easy for terrorists to hijack one or many LNG trucks . . . LNG trucking in densely populated areas is very dangerous."

The industry responded that most LNG will never be transported by truck and that accident and hijacking dangers are no greater than those for vessels and trucks carrying LNG than for those bearing gasoline or any other burnable material.

Consequences: "If (spilled) LNG spreads across a city in sewers, subways or other underground conduits, or if a massive burning cloud is blown along by a strong wind, a city may be faced with a very large number of ignitions and explosions across a wide area," the GAO report said. The prospect, it noted, is "very frightening,"

The scenario, the gas industry replied, is hypothetical and the likelihood of it occuring is unproved and small.

Liability: Financial and corporate arrangements are labyrinthine enough to mean that recovery of damages or insurance in case of an accident "face Department of Energy plans are long-litigation . . . the company may not be liable at all," the study said.

According to the industry, present and planned coverage is "more than adequate to cover any events that could be credibly postulated."

Research: Studies of spills have been on too small a scale to allow safety decisions based on them while Department of Energy plans are long-term though the need is immediate, the report charged.

The industry defended existing studies as valid in concluding that LNG can be handled safely.

Regulation: Responsibility for LNG is scattered and uncoordinated, while existing rules are inconsistent among levels of government and unevenly applied, the study reported.There is little expertise on the subject at any level, and the best idea would be establishment of a new federal Energy Health and Safety Regulatory Agency.

State, federal and local jurisdications have different interests and their rules should differ, the industry replied. There is no evidence that existing codes are inadequate and the existing industry has an accident-free record.