Wire / Rope for Spreader Bar

There are standards you have to follow for this. This is about the size you have to 3D model otherwise you will make it weigh too much. Special welding standards are also required. What do you plan in lifting 100 tons with :)

Please provide more details about your Spreader Bar. Is it existing Spreader Bar where in you want to replace the wire rope?. Or you want to design new one. If you are planning design new one then I would suggest leave the matter to mfr. of this item who has experience in such designing work.

Thanks for your response;

Actually i am designing a new spreader bar to lift 100 ton structural skid by using four slings at four corners. I have calculated the dia of 6x19 wire to be used as lifting sling. it comes about 75mm with a factor of safety of 7.2. but this dia is large enough. can you suggest me some idea or some person whom should i contact.

No dear;

I am trying to design a new spreader bar. I have calculated the diameter of the wire to be used in lifting but it is about 75mm which is large enough. i have used a factor of safety of 7.2, Is there anyone else who may calculate this diameter for me. I am using four slings to lift the structural skid.

Hi Mr.Khawar,

I do not know where you are located.If you are from India then I could help you. Wire Rope of 75 mm dia will be very big size and will not be flexible. You will have to reduce wire rope diameter and increase the number of falls. You will have to provide Pulleys for multiple falls of wire rope. You will have to consider friction losses due to pulleys. There are mfrs here who can supply you complete Spreader Bar. Are you going to suspend this below the EOT Crane?.

If your load is symmetrical and you are using a spreader the load per leg is going to be 50 tons. Most wire rope manufacturers design their cables for a safety factor of 5, I don't know if you are adding to this or trying to improve it to 7.2.

As a thumb rule for working load, we would square the diameter of the wire and multiply it by eight just to get a warm fuzzy feeling that we were in the ball park. Any good rigging chart will tell you the proper size and give you some limitations about angle and such. I assume you are using the original spreader beam steel and it will be correct.

If you take a quick estimate it looks like your are rigging for 70 tons on a straight pull per wire, you can double that in a basket hitch to help with load limitations of angles and such.

A sketch of the particulars would be helpful. Right now I think you are over rigged to high heaven.

Even with the lack of data, I believe your answer is good.

Dear Otha;

Plz elaborate your answer. As you have mentioned that; for working load, we would square the diameter of the wire and multiply it by eight; this results as 45000 sq. mm. what will it suggest.

Also what is the method to calculate the dia. of wire.