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Safe Working Load from Global-Pak Newsletter June 2017

by Global Pak
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We often get questions on what a Safe Working Load is and why do we need a Safety Factor of 5 to 1 to handle our bags safely? In the following few paragraphs we will try to give you the background of where the Safe Working Load has its origins and the core test procedures used to ensure a bulk bag or FIBC design that allows you to have the peace of mind to ensure your customer’s safety as well as your employees.

In describing the working condition to which the FIBC is going to be subjected, the terms used are the SWL (Safe Working Load) and SF (Safety Factor). These are the main safety ratings involved with bulk bags. The origins of the 5 to 1 safety factor originates from the OSHA sling lifting guidelines which can be referenced at www.osha.gov/Publications/osha3072.html these are not bulk bag or FIBCA standards, but general lifting standards that have contributed to FIBC handling guidelines.

The SF is given as 5:1 for single use bags. Safety Factor of 5:1 indicates a single use bag and 6:1 means UN rated or multiple use bag.

The safety factor of 5:1 means that the filled bag when subjected to hydraulic pressure should sustain a minimum of 5 times the SWL after 30 cycles of 2 times the SWL. After the 30 cycles of 2 times the SWL it is taken on the final 30 cycle to destruction, meaning it is subjected to maximum hydraulic pressure until the bag fails.  During this final cycle the bag must pass 5 times the SWL or it is not suitable for normal use.  The maximum pressure the bag design can withstand is called the peak load test. So if the SWL is 2200 lbs (1000 kgs) with SF of 5:1, the bag when subjected to the cyclic test and peak load test is considered passed if it breaks at 11000 lbs (5000 kgs) or greater.

A safety factor of 6:1 means that the filled bag, when subjected to hydraulic pressure, should sustain a minimum of 6 times the SWL after 70 cycles of at 4 times the SWL. If the bag breaks before 6 times the SWL pressure then it is not suitable for the required duty for UN rating or as a multi trip bag. So if the SWL is 2200 lbs (1000 kgs) with SF of 6:1, the bag when subjected to the cyclic test and peak load test is considered passed only if it breaks after 13200 lbs (6000 kgs) pressure or greater.

These standards were established by EFIBCA in 1985 to ensure maximum safety while designing the FIBC. The latest standard is ISO 21898.

As mentioned earlier, 5:1 indicates a single use of the bag. When we talk of single use FIBC it means the whole process from taking the FIBC from filling the bag to the discharge of the material from the bag. Any FIBC will typically be handled as follows and this process will be defined as "single use":

  1. Bag is filled with the material
  2. After filling it is moved to the warehouse of the producer
  3. From the warehouse it is moved to the truck for transportation to customer.
  4. At the customer the bag is moved from the truck to the warehouse
  5. The filled bag is then moved from warehouse to the shop floor for discharging
  6. Material from the bag is discharged.

We are hoping that you find the information that we put out as helpful as we at Global-Pak find that sharing information and knowledge with our customers helps everyone to have a better experience with their bulk bags. If you have further questions please contact your sales rep or reach out to us at info@global-pak.com for more information.



For the full version of our June 2017 Newsletter click here - http://conta.cc/2uk2mgJ

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