A Guide to Flexible Intermediate Bulk Container Vocabulary

A Guide to Flexible Intermediate Bulk Container Vocabulary

Before deciding to purchase FIBC bulk bags, it’s important to educate yourself. Part of that process is catching up on all of the different terms. We made this guide to help you make the most informed purchase.

Synonyms for flexible intermediate bulk containers

Wikipedia defines a FIBC/bulk bag as “A flexible intermediate bulk containerbulk bag, or big bag, is an industrial container made of flexible fabric that is designed for storing and transporting dry, flow-able products, such as sand, fertilizer, and granules of plastic.”

Here are some other common terms for FIBCs:

  • 1 ton bag
  • Woven polypropylene bulk sack
  • Bulk sack
  • Tote


Terms related to FIBC features

Duffle Top

Duffle tops are thin, lightweight top panels that are the same width and depth as the four sides of the bag. The larger opening provides more flexibility in filling options and the types of machinery it can be used with.           

Spout Top

A spout top is a sturdy spout sewn into the top panel of the bag that is cylindrical and narrower than the width and depth of the bag.

Flexible intermediate bulk container - duffle top construction, National Bulk BagFlexible intermediate bulk container - spout top construction, National Bulk Bag


Baffles are extra fabric panels or pieces of string sewn into each of the bag’s four corners. This reinforcement allows the bag to better hold it’s square shape when filling.

Flexible intermediate bulk container - baffle construction, National Bulk Bag


A coated bag is constructed like a standard bag, however, before it is sewn together an additional polypropylene film is added to the bag’s fabric sealing the small gaps in the weaves. A non-coated bag does not have this film.

Lift Loops

Lift loops are fabric loops attached to each of the four corners at the top of the bag. These handles can be used by forklifts to lift the bag and make it significantly easier to handle.


Discharge refers to the processes of emptying the bag.


FIBC Safety Terms

Flexible intermediate bulk container - safe working load, National Bulk BagSafe working load

The amount of weight (usually displayed in lbs.) a bag can safely hold.

Safety factor ratio (SFR)

The ratio that represents the factor of how many times the safe working load a bag can carry.

Example: a 5:1 SFR means that a bulk bag can carry 5 times the defined safe working load.

UV stabilized

A bag that has been UV stabilized is protected from long-term UV degradation cause by exposure to ultraviolet radiation.

Fabric weight

Fabric weight (usually measured in grams per meter squared and ounces per square yard) is a measurement of how much a fabric weighs. The higher the number, the denser a fabric will be.


Volume is the amount of space that a substance or object occupies, or that is enclosed within a container.


Food Grade Terms

Flexible intermediate bulk container - GFSI, National Bulk BagGFSI (Global Food Safety Initiate)

GFSI was created by the food industry in order to drive global collaboration and advance food safety.

BRC certified

BRC (GFSI recognized), or British Retail Consortium, is a trade association from the UK. BRC certified manufacturing facilities are facilities that meet minimum BRC standards. Food grade FIBCs are manufactured in BRC certified facilities.

Flexible intermediate bulk container - food grade, BRC, National Bulk BagAIB certification

AIB, or the American Institute of Baking is an institute that defines standards for facilities. They are not GFSI recognized, but instead have their own set of standards for facilities that manufacture food grade goods.

Food grade

This term refers to something that has been approved for use in the food industry by one or multiple organizations.

Flexible intermediate bulk container - SQFI, Food Grade, National Bulk BagSQFI (Safe Quality Food Institute)

The SQFI (GFSI recognized) is an institute that has created food standards and testing processes. They also certify facilities for use in the food industry.

Virgin resin

100% virgin resin, used in the manufacturing of food grade bags is polypropylene resin that has never been used. It must contain 0% recycled materials.

FDA approved FIBCs

FDA approved FIBCs are a myth. The FDA (Food and Drug Administration) does not set standards for bag manufacturing or certify FIBCs for safe food use.


Bulk bag accessories

Form fit liner

These are liners that are specifically designed to take the exact form of the bag they are lining including any construction related to charge/discharge (spout, duffle, etc.).

Tubular liner

A tubular liner is a cylindrical liner with no discharge points. One end is often heat-sealed.

Gusseted liner

Gusseted Poly Bags provide a precision fit when inserted into a bulk bag. Typically, gusseted poly bags come on rolls and are inserted into the bulk bag before filling. The bag then folds out when the material is being loaded and takes the interior shape of the bag. They are also ideal for protecting pallet loads or items to be stored.

Tabbed liner

Having a liner tabbed into the body of the bulk bag will secure the liner at specified anchor points on the interior of the bag. This will keep the liner in place during loading and discharging of the material. Tabs are pieces of fabric that are attached to the interior corners of the bag and the liner.

Flexible intermediate bulk container - polyethylene liners, National Bulk BagPolyethylene liners

Polyethylene liners are common plastic bags used to line the inside of FIBCs. They are flexible in nature and have a variety of applications.

Document pouch

A small plastic pouch sewn into one side of the bag used to store identification documents relating to the contents of the bag.

Stevedore straps

Heavy-duty straps (usually 2 as a single pair) that are threaded through each set of lift loops on opposing sides of the bag to create a single lift point.

Sift proof seams

Sift proof seams are seams in a bulk bag that are specifically designed to prevent fine materials (generally powders) from leaking through the seams.


Replacement Level Products

Bulk container

A rigid rectangular container often used similarly to a FIBC.

Gaylord boxes/pallet box/bulk box

A large box made of cardboard fused/attached on top of a wooden pallet.

Bulk bins

A bulk bin is a large rigid container.         


Thanks for reading!

A Buyer's Guide to Bulk Bags - National Bulk BagThanks for reading our blog post "A Guide to Flexible Intermediate Bulk Container Vocabulary"!

It's our mission to make your buying experience easy, informative, and enjoyable. We also want to share our knowledge with you so you can make the best purchasing decision for the company you represent. Our Buyer's Guide to Purchasing Bulk Bags includes critical information ranging from types of bags to important safety information about handling and transportation.

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May 23, 2017

Categories: Bulk Bags

About the Author: Janette Lais

Janette is the Director of sourcing for National Bulk bag. Janette is also a graduate of the University of Minnesota in Minneapolis. Janette has been in the packaging industry since 2004 and has held many roles such as Operations and purchasing manager, Purchasing management project manager. Before entering the packaging industry, Janette spends 19 years at a manufacturing facility where she held production scheduling, product manager, and purchasing manager position. Janette is an outdoor enthusiast and enjoys hiking and fishing in her free time. She also enjoys spending time with family and friends and her three dogs.

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