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Testing is a vital part of quality management and assessing whether bulk bags perform as expected. There are a number of tests that bulk bag manufacturers will conduct, including top lift, topple and tensile tests. These allow manufacturers to guarantee the performance and effectiveness of a batch of bulk bags, giving customers peace of mind that their packaging products will work as expected.

Custom Bulk Bags is a leading manufacturer and supplier of high-quality bulk bags in South Africa. We produce up to 3.5 million bulk bags per year – all of which have a minimum safety factor rating of 5:1. Our products can safely hold between 500kg and two tonnes of material per bag, depending on your specifications.

We also perform several tests on each batch of bulk bags, including the top lift test. As the name suggests, this is an assessment of the safety factor rating and the bag’s ability to hold the specified weight of material. If a bulk bag is rated for two tonnes, then it should be able to hold 10 tonnes without breaking if its safety factor rating is 5:1. This is verified by the top lift test.

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How the top lift test works

The assessment starts with a cyclic test, whereby the sample bulk bag is put under a repeat process of load and de-load. This simulates the long-term ability of the bulk bag to hold weight when it’s lifted by cranes or forklifts and then set down again. The cyclic test allows manufacturers to see if any seams, lifting loops or bottoms show signs of strain after being loaded multiple times. 

The sample bag is filled with plastic pellets or rubber to mimic a full load. Then it’s hoisted onto the test machine to begin the cyclic test at its safe working load. The cyclic test usually comprises 30 cycles for a 5:1 bag and 70 times for a 6:1 bulk bag. 

Next, the sample bulk bag is subjected to a maximum load test. This is the absolute limit of the bag’s safe working load, based on its safety factor rating. The sample bag must pass this test in order for the batch to be signed off with the appropriate safety factor rating. 

The maximum load test is sometimes conducted until the bag fails. The machine records this weight and verifies that it meets the necessary safety factor rating. These assessments ensure that our bulk bags will meet your expectations and quality standards. 

Three fully loaded bulk bags hanging by a stevedore strap in an industry warehouse

Quality assessments at Custom Bulk Bags

In combination with numerous other tests, we can safely say that our products are capable of performing within their safe working loads. These tests allow us to spot-check for any manufacturing defects and to investigate any design flaws with customised bulk bags. 

The top lift test is an investment in safety; your employees need to know that they can trust the structural integrity of bulk bags when being lifted and moved around your facility. Safety should always remain the number one priority when working with fully loaded bulk bags. That’s why it’s important to buy from a reliable and reputable bulk bag manufacturer.

Custom Bulk Bags has operations in Durban and Bloemfontein but we are able to ship our products nationwide with minimal delays. Our bulk bags are UN-certified and we hold ISO 9001 certification for quality management. Speak to one of our consultants for advice or to be guided through the ordering process. For more information about our bulk bags, please contact us today.


Custom Bulk Bags is a leading South African manufacturer of woven polypropylene bags for various industries, such as mining, chemicals and food. We are able to produce over 3.5-million bulk bags per year, keeping our customers in stock at all times. Our bags adhere to the highest levels of quality as a result of our stringent in-house testing and quality control programmes.

Custom Bulk Bags holds ISO 9001 certification and we currently have a number of UN-certified designs. We are a Level 2 B-BBEE manufacturer and supplier and fall under the ownership structure of Deneb Investments Limited. For more information on our products, contact Follow us on Facebook, LinkedIn and Instagram for our latest news and industry insights.