Seal Technology Changes for the Better
Loading dock seals have been notoriously subject to damage for a wide variety of reasons. Yet much has changed with dock seals since they were first introduced decades ago. Advances in materials and engineering have led to dock seals that withstand the abuses of today’s trailers and dock conditions. The result is greater durability, sustainability and performance.
Dock Seal Insights
Foam dock seals form a gasket-type seal around the sides and tops of a trailer as it is backed into the dock. The tightly compressed seal reduces the infiltration of bugs, dust and other contaminants. Additionally, companies can reduce energy costs by hundreds of dollars per year per dock position with the right seals. Seals also help keep outside elements from entering a facility, which protects products from being damaged or contaminated — and keeps employees safe and comfortable.
Dock seals typically perform well the first couple of years after they’re installed, but soon begin to wear out. It’s no surprise, given that seals are severely compressed against the building wall every time an 80,000-pound trailer backs into the dock. But there’s more to it. Most of the damage has to do with how the trailers and seals interact and “fight” each other while in use. Here are insights that have helped guide 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. Wear pleats provide some protection, but often not enough.
- Trailer motion causes extreme friction. As trailers bounce up and down during loading and unloading, dock seals are constantly abraded. Wear pleats and tougher, more wear-resistant fabrics have been introduced over the years to help. Yet trailer motion remains a challenge.
- Yard jockeys cause specific damage. Trailers being shuttled by yard jockeys create a severe tugging motion on dock seals that can cause the foam of the head pad to separate from its backer, and twist or sag in its cover. Sometimes, the head pad of the seal can even be pried off of the wall.
- Head pads burn from compressed trailer marker lights. When marker lights at the top rear of trailers are compressed into foam seals, the heat from the lights begins to build, gradually reaching dangerously high temperatures. Foam begins to smolder, and if a trailer is in place long enough (as little as 20 to 30 minutes), the head pad can self-combust.
Tackling the Issues Head On
Dock seal manufacturers have taken advantage of emerging technologies in materials and design to address costly damage issues. Some of the more recent improvements include:
- Friction-resistant fabric. A pebble-grained coating creates a slippery surface that trailers slide against when in motion at the dock, thus better protecting the fabric from wear.
- Pads without overlapping pleats. Replacing wear pleats on seal corners and side pads with single-surface, friction-resistant reinforcing removes sew lines and fabric catch points. There is less chance for tearing and snagging, and greater overall resistance to wear over time.
- Reinforced wear points. Upper corners and insides of the side pads are frequently reinforced with multiple layers of materials to resist damage in high-wear areas. High molecular-weight polyethylene (HMWPE) sheeting reinforces these high-impact, damage-prone areas.
- Replaceable wear components. Parts of the dock seal that wear out fastest (such as the upper corners) have become easy to remove and replace in some dock seals.
- Impactable, movable headers. Some head pads are designed with reinforcing panels embedded in the foam to prevent sagging and keep them sturdy under impact. Other protective measures include eliminating the steel or wood backer so the head pad can float with trailer movement, reducing friction and wear. This pivoting action also prevents head pads from being pried off of the wall in yard jockey situations.
- Heat-dissipating materials. Fire-retardant foam and fabric are ineffective in preventing the heat buildup that can lead to fires. Heat-dissipating, layered foil technology has been added to protect against the damage and danger of burning headers.