FIBC Bag construction refers to the way that the sheets of woven polypropylene are sewn/stitched together to form a bag. There are several different construction types and these types can have a big impact on the SWL (safe working load), industry applications, and safe handling of the bag. There are 3 main constructions of FIBCs that are ideal for different storage requirements, as well as being cost-effective. Keep reading to learn the differences between them, as well as help you to determine which type may be more suited to your bulk packaging needs. 

U-Panel Jumbo Bag Construction

U-panel bulk bags are constructed with three body panels – one that runs the full length of the bag forming the bottom and two sides and two additional pieces of fabric sewn into the larger piece that form the other two sides. Similar to other construction types, the U-panel bags will maintain a square shape when filled, especially a U-panel bag with baffles. U-panel bags are an industry standard and the most popular type of construction offering high safe working loads (SWLs) and solid durability. U-Panel FIBC bags have a 5 : 1 safety ratio and come in 2,000, 3,000 and 4,000-lb sizes for transporting dense, heavy materials.

Circular Bulk Bag / Tubular big bag Construction

Circular FIBCs/ Tubular big bags are made with a tubular piece of fabric that forms all sides of the bag allowing for stitching only for the top and bottom of the bag. There is a common misconception with circular bags regarding their shape when filled. While they still resemble square/rectangular bags, they will hold that shape the least of the construction types when filled. Tubular bags are less labor intensive to make, so they are more cost effective to purchase. They are ideal for products generally transported and stored in containers built to carry up to 3,500 lb., and the tubular body design with no side seams is ideal for holding in some fine materials without using a liner.

4-Panel Bulk Bag Construction

As evident from its name, the bag is constructed with four individual pieces of PP woven fabric and a separate piece of fabric to form the bag’s squared structure. When filled, a 4-panel FIBC bag will hold its square shape similar to other construction types. Typically, 4-panel FIBC bags will hold their shape better than the U-panel big bags, and U-panel bulk bags will hold their shape better than a circular / tubular bulk bag. The biggest drawback to 4-panel bags is the large amount of stitching required to keep the bag together. This can allow for more areas of the bag prone to failure. However, 4-panel bags are ideal for storage due to the way they hold their shape when filled. The bag can help save transportation and storage costs as they retain their squared shape and the bags are easier to stack.

The 4-Panel bags are the ideal choice to transport chemicals, minerals, salts, fertilizers, resins, pellets, or fine powders. The 4-panel bags can be custom-made to the buyer’s standards with different safe working loads (SWLs) 1000 pound to 4400 pounds and safety factors from 5:1, 6:1, and 8:1.


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