SHORT ANSWER: No, you cannot use ratchet straps for lifting. Ratchet straps are designed to secure loads in place during transport; they are not designed, tested or certified for lifting applications.
Ratchet straps can be extremely useful if you're trying to stop cargo shifting around while you're on the road, but they are not lifting slings and should not be used as such.
Every Tensys ratchet strap has the words NOT FOR LIFTING printed clearly on the label. This warning is there for a very good reason: using a ratchet strap to lift or lower a load may cause the strap to fail, potentially causing severe damage and/or injuries.
If you need to lift a load, you must use suitable lifting equipment such as a certified lifting sling. Luckily, we also sell textile lifting slings that are specifically made for heavy lifting jobs.

