Steel building imports from China that fall apart easily are making U.S. manufacturers and constructions firms more than a little nervous.

The biggest concern is hollow structural sections widely used in construction of skyscrapers, bridges, pipelines, office and commercial metal buildings. This high-strength steel is also commonly used in power lifts, cranes, farm equipment, furniture and car trailer hitches.

Chinese high-strength steel tubes and pipes are also a potential problem. They’re used extensively in power plants and in large industrial boilers, having to withstand enormous pressures and heat around the clock for weeks or months on end.

This kind of steel also is used extensively in scaffolding that's erected on metal building exteriors during construction or renovation, as well as for interior work.

Inferior high-strength steel could cause catastrophic failures of buildings and pipelines.

This is a large worry for structural engineers who will be working overtime as states embark on what amounts to a crash program to shore up bridges, following the collapse of the Minnesota span over the Mississippi River.

Dan Malone, construction manager for Garneau Manufacturing, based in Morinville, Alberta, Canada, an energy service company that works with many imports, said tests on a lot of 80 tons of Chinese steel building products found "the welds failed horribly."

Malone said there was no question that if the steel had been fabricated into a finished product and installed it would have failed and "would have killed somebody."

It's unlikely that existing metal buildings or bridges are in imminent danger of collapse. U.S. metals fabricators periodically test imported steels to assure they met specs for strength, hardness and durability.

Building owners and power plant operators will bring in structural engineers to test the steel. If any structurally deficient steel building material is found, companies will shore up pillars, girders and trusses or replace boiler pipes entirely.