It may be the only set of coke ovens in the Eastern United States capable of being operated, but not in operation.

That's how a coking coal supplier describes what's happening at Wheeling- Pittsburgh Steel Corp.'s Monessen plant 25 miles southwest of Pittsburgh.The plant's ovens have been in operational limbo, technically on hot idle, since June 1986. Coke ovens must be kept fired to prevent them from falling into a state of disrepair that would render them useless.

Energy costs to Wheeling Pitt, which is reorganizing under Chapter 11 of the bankruptcy laws, have been about $150,000 a month.

But now BMAC Inc., a Delaware-incorporated company, is considering buying the coke battery and bringing it back into production, bucking a trend that has seen widespread reductions in domestic coke-making capacity.

BMAC, Wheeling Pitt and one of the steel company's creditors have agreed to a plan under which they will share the cost of keeping the coke battery on hot idle until June 1 while BMAC evaluates the feasibility of bringing the battery back on line.

One optimistic coking coal supplier speculated that coke from the Monessen plant, located on the Monongahela River, could be produced at costs that would make it price-competitive at steel plants located on Eastern state waterways, in the Great Lakes region, and possibly even at coastal mills.

He estimated production costs, depending on BMAC's ability to sell coke- oven gas, would be about $82 to $84 a ton, and transportation rates would be about $12 to $14 a ton.

That would compare with a price of roughly $100 a ton at U.S. ports for imported Japanese coke of comparable quality.

Other foreign suppliers who have cashed in on the upturn in U.S. steel making and increased demand in the U.S. market for coke include Australia, Yugoslavia, and Canada.

An international coke and coal trader far less optimistic about the chances of the Monessen battery being brought back into production commented that several companies have looked into the plant and judged it to have high operating costs.

He said BMAC would have to get a long-term contract to supply coke, or an extremely low asking price from Wheeling Pitt, to make the venture pay off.

Commented another trader, it's something I would not want to get into.

The coke market is so . . . volatile, you absolutely cannot predict it.

The Monessen plant was producing 925 tons of coke a day before being idled.