How To Select And Install Dunnage Bags For Intermodal And Container Shipping

Dunnage Bag An inflatable bag placed between cargo units to prevent shifting during truck, rail, or container transport. Proper selection and installation are critical for safe intermodal and containerized shipments—this guide covers sizing, protection, inflation, and inspection steps typical in U.S. operations.

Start with a quick assessment of the cargo: load dimensions, void sizes, contact surface material, and expected transit conditions. Dunnage bags are most effective when they contact broad, stable surfaces. Measure the height and width of voids and note any protrusions, straps, or sharp edges that will need protection.

Selecting The Right Bag Size And Type

Bag size selection is the single most important decision. As a rule of thumb:

• Small Voids (2–6 inches): Use small tubular or corner airbags designed for low-volume gaps.
• Medium Voids (6–24 inches): Standard kraft or woven bags sized to fill the gap without overextension.
• Large Voids (24+ inches): Use large woven dunnage bags or multiple bags in series to distribute pressure.
• Material Choice: Choose woven polypropylene bags for reusability and wet environments; kraft paper bags are economical for one-way exports.

Preparing The Cargo And Container

Preparation reduces failures and speeds installation:

• Clear Debris: Remove loose dunnage, dust, or cargo fragments from the void area.
• Apply Edge Protection: Use cardboard, foam, or plastic corner protectors where straps or metal edges exist.
• Ensure Even Contact: Stack pallets squarely to provide consistent surfaces for bag faces.

Inflation: Pressure, Tools, And Technique

Inflation must follow manufacturer guidance. Typical steps include:

• Use The Right Pump: Pneumatic pumps with pressure gauges are preferred; manual pumps can be used for small bags.
• Inflation Pressure: Inflated to a firmness—not overfilled; manufacturers publish target PSI or psi ranges. Avoid bulging beyond cargo faces.
• Staged Inflation: Inflate in stages while checking contact points, ensuring the bag evenly expands and transfers load pressure.

Placement Patterns For Common Loads

Recommended placement patterns vary by cargo configuration:

• Unitized Pallets In A Container: Place bags between pallet rows and against container walls at regular intervals (every 4–6 pallets) to prevent shifting along the length.
• Heavy Single Items: Use multiple bags around the base or combine airbags with wood blocking for a hard stop.
• Railcars: Secure at both ends of the shipment and between groups to limit longitudinal movement under heavy braking.

Inspection And Re-Check Procedures

Inspections before transit and after initial movement reduce claims:

• Pre-Departure Check: Verify inflation pressure, bag condition, and edge protection before sealing the container.
• Short-Run Re-Check: For truck moves, re-inspect after the first few miles and re-inflate if settling occurs.
• Post-Unload Reuse Check: Inspect reusable woven bags for cuts, seam failures, or contamination before storing.

Recordkeeping And Training

Maintain records of securement methods and train staff. A simple log that records bag type, placement pattern, inflation pressure, and inspector initials supports quality control and helps resolve damage claims. Train warehouse and transportation staff on installation steps, pressure checks, and hazard recognition (pinch points, punctures, and over-inflation risks).

In short, the Dunnage Bag becomes a reliable part of an intermodal securement strategy when properly selected for void size and load type, installed with correct protection and pressure, and inspected routinely. Following manufacturer guidance and carrier regulations reduces damage, downtime, and liability on container and intermodal lanes.