How this tough glass
keeps steel workers safe

Working with molten steel requires a few extra safety precautions.

Working with molten steel requires a few extra safety precautions.

In steel mills and foundries, workers face extreme temperatures and a number of dangers, from ladles of molten metal to potential steam explosions during slag handling.

One of the protections in place to keep workers safe are blast-resistant window systems. These window systems cannot rely on just any glass. The glass material must have unique technical properties in order to meet a number of requirements.

Here’s how technical glass holds up in one of the most extreme work environments.

The two biggest dangers of working in a steel mill are fire and slag explosions. Liquid steel can range in temperature from 2,730 to 2,890 degrees Fahrenheit, making it a fire hazard if it comes into contact with anything from fuel to conveyor belts. The same goes for the slag, which is the byproduct of the process that separates metal from ore. The most dangerous combinations and reactions occur when hot, molten slag interacts with water.

What is a slag explosion?

You may not expect it, but water plays an important role in the steel-making process. Slag is commonly “watered” to lower its temperature during cooling and tempering. Watering slag the right way allows steam to escape. However, if slag comes into contact with water in a confined compartment, the water heats up so fast that it turns instantly into steam, causing a vapor explosion. This is extremely dangerous and can result in deadly accidents.

The blast-resistant window system, needed to protect workers, must stand up to the force of an explosion as well as the extreme heat encountered every day.

To test different configurations, equipment manufacturers put several glass configurations to the test, including one trial that used five tons of TNT, to simulate blasts far beyond the force of a slag explosion.

The results showed the best materials and construction to shield workers from the extreme heat of molten rock and metal while loading and unloading slag.

How to protect steel workers

The final design configuration, realized by Cincinnati Gasket, included a steel frame as the backbone for heat-resistant borosilicate glass. The borosilicate glass was treated with a variety of coatings, including IR reflective coatings to protect against extreme heat. A layer of laminated glass helps guard against explosions.

The particular glass used in some applications is BOROFLOAT®, a floated borosilicate glass that can withstand high and fluctuating temperatures and possesses a high mechanical strength. The float process, as well as the ingredients in the glass, produce a clear, flat glass that gives steel workers full visibility over the task they’re doing while protecting them on the job.

Here are some examples of what the cabs on the loaders look like with the blast-resistant windows:

Below is what the glass looks like after an explosion. While it’s scarred on the outside, the view from inside the cab is a different story.

Working in a steel mill or foundry can be a dangerous job. With the help of technical glass like SCHOTT BOROFLOAT, steel mill workers can feel a little safer.

May 8, 2018


Kim Kennell
Home Tech
SCHOTT North America, Inc.