Ports, transportation consultants and U.S. steel producers are all enjoying the fruits of a boom in exports of steel, but shifts in trade laws and currency values, as well as shortages of specialized transportation equipment, could cloud the future.

Experts at this week's Breakbulk Transpo here said Monday that the

weakening in the value of the U.S. dollar helped spark the boom by reducing the cost of U.S. steel to foreign buyers. But a strengthening of the dollar could easily have the opposite effect."The currencies were all in our favor" over the last 18 months, said Jerry Starnes, sales manager for Hickman, Ark.'s Nucor Steel plant, which has shipped about 300,000 tons, or about 15 percent of its total production, overseas so far this year.

K.W. "Butch" Almstedt, a trade lawyer with O'Melveny & Meyers in Washington, said changes in the international trade law regime also threaten exports as other nations copy the same kind of strict anti-dumping laws that have marked U.S. trade policy over the last decade.

''We're (O'Melveny & Meyers) probably spending more time today defending U.S. exporters" from dumping claims than defending foreign importers, Mr. Almstedt said. "The amount of disputes that are now (occurring) in foreign jurisdictions is growing by leaps and bounds."

For Basil Rusovich, chairman and chief executive in New Orleans at project cargo specialist Transoceanic Shipping Co., international trade law is only one of the many legal and practical matters he must keep track of in order to do his business.

Shipping project cargoes, large pieces of equipment for building such facilities as refineries and power plants, often requires navigating through a thicket of local regulations and permit processes in order to get the cargo

from the port of discharge to its final destination inland, Mr. Rusovich said.

Project cargo shippers often also have to obtain specialized equipment, including floating cranes for ports without cranes and vessels equipped with their own loading equipment.

''The shortage of breakbulk vessels presents a very serious problem," Mr. Rusovich said. "They (shipowners) seem to forget there are sophisticated pieces of cargo that they can't possibly handle" in containerships.

But, despite the shipping difficulties and the potential for currency fluctuations to turn boom into bust, Mr. Rusovich remains confident that project cargo shipments will continue to provide business for U.S. ports

because of the tremendous demand for the kind of modern industrial equipment that U.S. manufacturers can provide.

''The international markets are growing tremendously," Mr. Rusovich said. "This, of course, is the best hope of the future for this industry."