Disclaimer: The information on this page has not been checked by an independent person. Use this information at your own risk.
DNV have designed some calculations in document DNVGL-ST-E273 December 2016 to allow you to calculate the stresses in padeyes (also known as lifting eyes). Please note for the purposes of this document, I have not included the use of cheek plates, or weld calculations, which will follow on a later page
To use the calculations, you will need to know the sling load, for which you can use the sling load calculator previously released, and the size of the shackles you will be using. I recommend using Green Pin Shackles which are suitable for your lift.
The image below shows the key dimensions and how they relate to a lifting pad. Note that this pad eye is designed for a vertical pull.
You can control the hole diameter, radius of the pad, thickness of the pad and material of the pad. Typical structural steels are S275 and S355 in the UK and as per section 3.4.3 the allowable stress is 85% of the yield stress. Both the bearing and tear out stress must be less than the allowable stress.
Key points to note are as follows:
1. As you increase hole diameter relative to pin diameter the calculation changes - a snug fit reduces bearing stresses.
2. Sheet metal is available in a range of sizes - see Parker Steel for guidance
3. As you increase radius, ensure that your shackle inside length (dimension f) will fit, and allow clearance for slings.
Calculating stresses in the weld will be another calculation which follows in the near future - it is worth noting that a welding flat has been detailed in the image above - this will allow a secure rigid connection to the base or component you are lifting from. Don't forget to check the base component you are lifting to ensure it is suitable for the lift you intend to conduct.
Please use the calculator below to experiment with different designs, if you have any questions on how the calculator works, please contact me