Loading Dock Seals have Toughened Up

Some of the first loading dock seals — those fabric-wrapped foam pads surrounding dock door openings — were installed in 1959 to help prevent the infiltration of outside elements into a facility while trailers were loaded and unloaded. They quickly became popular throughout the world as a relatively low cost way to save energy and gain environmental control at the dock. There was one problem, however.

By nature of their function and design (repeatedly impacted and compressed by semi-trailers) dock seals were subject to damage. Wear and tear can come quickly on a dock with heavy trailer traffic, resulting in diminished sealing effectiveness, tattered appearance, and high repair and replacement costs.

Today, however, advances in materials and engineering have led to “new age” dock seals that withstand the abuses of today's trailers and dock conditions. The result is greater sustainable durability and performance.

Controlling the Elements

Foam dock seals form a snug gasket-type seal around the sides and tops of a trailer as it is backed into the loading dock. The tightly compressed seal helps keep heated or cooled air inside the building when the dock door is open and goods are being loaded or unloaded. Studies show that companies can reduce their energy costs by hundreds of dollars per year per dock position, simply by installing an effective seal that is sized and applied to match the variety of trailers being serviced. Seals also help keep outside elements from entering the facility, which protects products from damage, keeps employees safe and comfortable, and reduces infiltration of bugs, dust and other contaminants.

Dock seals typically perform well the first few years after installation, but they soon begin to wear out due to the pressure and friction inflicted by constant contact. Throughout the years, dock seal damage has been accepted as a costly but inevitable reality. Companies simply became accustomed to the ongoing costs of seal maintenance and replacement, or the shabby appearance and diminishing effectiveness of seals that weren't regularly repaired or replaced. Yet continually rising energy costs, the ongoing need for improved profit margins, and increased attention to safety and regulatory issues dictated the need for significant improvements in dock seal technology.

The sources of dock seal damage

Dock seals are severely compressed against the building wall every time an 80,000 lb. trailer backs into the dock. Besides compression, most of the damage has to do with how the trailers and seals interact and “fight” each other while in use.

The following findings from research and development in dock seals over the years have guided the industry's product improvement efforts:

Dock seal corners wear out first. Sharp projections in trailer corners dig, cut and chew into the foam and vinyl cover fabric. Dock seal manufacturers began reinforcing this area with additional layers of fabric, called wear pleats, in 1962. Pleats are helpful and provide some protection, yet this still remains the most damage-prone area of dock seals today.

Trailer motion causes extreme friction. As trailers “bounce” up and down during loading and unloading, dock seals - under great pressure of the backed-in trailer - are constantly abraded. Wear pleats were added to dock seal side pads early on to help resist this friction, but the advent of air-ride trailers in the 1980s and ‘90s exacerbated the problem. Tougher and more wear-resistant fabrics have also been introduced over the years, yet despite the improvements, the immense pressure and friction from trailer motion continue to destroy dock seal components.

On docks that use yard jockeys (also known as yard mules or shunt trucks), which shuttle trailers between dock positions, dock seals are subject to some unique sources of damage. When trailers are raised while parked at the dock, extreme inward and downward pressure is exerted against the dock seal head pad. The severe tugging motion can cause the foam of the head pad to separate from its backer and twist or sag as a result. Also, when a raised trailer is shuttled to a dock position and then lowered into place, the rear of the trailer frequently becomes caught beneath the head pad, and simply pries it off the wall. This problem, often referred to as “head pad pop-off,” creates a costly maintenance headache.