Webbing Sling Safety Factor: A Complete Guide to Safe Lifting and Why It Matters

In industrial lifting, webbing sling is the tool of choice for handling heavy equipment due to its lightness, flexibility and strength. However, ensuring the safety of lifting operations requires a thorough understanding of the Safety Factor. In this article, we will analyze in detail the definition of Safety Factor, its importance, selection criteria and how to enhance efficiency through compliant use, so as to help you choose a cost-effective and high-quality product.

1. What is the Safety Factor of a webbing sling belt?

The safety factor is the core indicator of the relationship between the load carrying capacity and the ultimate breaking strength of a sling. It is defined as:

Safety Factor = Minimum Breaking Strength (MBS) / Safe Working Load (WLL or SWL)

For example, if a round sling has an MBS of 35 tons and a safety factor of 7:1, its WLL is 5 tons. This means that the actual load-bearing capacity of the sling far exceeds the nominal value, providing a cushioning space for sudden loads or environmental changes911.

Common Safety Factor Ranges

• 4:1: For sling use under very small loads.

• 5:1: For regular industrial scenarios such as light equipment handling.

• 6:1: Suitable for most industrial lifting scenarios, meeting standard strength requirements.

• 7:1: Recommended for high risk and large industrial lifting environments (e.g. construction, marine, mining) to provide greater safety redundancy.

Special Needs: Some industries may require a factor of 8:1 or higher, to be selected according to specific regulations.

Additional Note: Please be aware that according to ISO, EU and Chinese industry standards for webbing slings, a safety factor of 6x and above is required.

We can provide professional tensile strength test report of lifting slings.

2. Why is the safety factor so important to lifting safety?

• Resistance to dynamic loads and unexpected shocks

  During the lifting process, dynamic stresses are generated by load shaking, acceleration changes, etc. A safety factor of 7:1 effectively absorbs these additional stresses and prevents sudden breakage of the sling.

• Compensation for material wear and environmental effects

  Prolonged exposure to UV rays, chemical corrosion or friction can cause the strength of the webbing to deteriorate. The high safety factor extends the life of the sling and reduces the cost of frequent replacements.

• Compliance and liability avoidance

  European, American and ISO standards generally require a safety factor of not less than 5:1, while high-risk industries such as maritime and energy are mandated to use 7:1. Using compliant products avoids legal disputes and enhances a company's safety reputation79.

• Increase operational confidence and efficiency

  When employees know that webbing sling eye and eye has a high level of safety redundancy, they can focus more on the workflow and reduce misuse due to concerns about equipment failure.

3. How to choose a webbing sling with the right safety factor?

Step 1: Evaluate Application Scenarios

    Construction & Mining: 7:1 recommended for irregular loads and harsh environments.

    Manufacturing & Logistics: 5:1 6:1 meets standard requirements but needs to be checked regularly for wear.

    Marine & Chemical: Choose corrosion-resistant materials + 7:1 factor, such as polyester fiber + anti-acid coating or Heavy duty polyester webbing sling.

Step 2: Calculate actual load requirements

    Formula: WLL = Load weight ÷ Lifting angle factor

    Example: Load 2 tons, use double lifting point 90°, single sling WLL need to be ≥ 2 tons / (2 x 0.7) = 1.43 tons. Select a sling with WLL ≥ 1.5 tons and a safety         factor of 7:1 (MBS ≥ 10.5 tons).

Step 3: Verification Certification and Marking

    Compliant webbing sling belt should be clearly labeled with WLL, safety factor, MBS and production lot number, and be accompanied by third-party testing certificates (e.g. CE, OSHA).

4. 5 Codes of Practice for Extending the Life of Slings

Pre-use inspection: Check for cuts, wear and tear, and discoloration (UV damage markings).

Avoid contact with sharp edges: Use sheaths to protect slings from fiber cuts.

Regulate storage: Store in a dry and lightproof environment, away from chemicals.

No overloading and knotting: even short-term overloading may cause internal fiber breakage.

Regular professional testing: Strength test by certified organization every 6 months.