Padeye Safety Factor

[AlexH15]

Hello All,

Sorry if this is in another post, but I have searched for hours and I cant seem to find anything that states outright what the safety factor on a padeye should be.

I have a client who wants me to verify another engineer's design for some padeyes. The padeyes were not designed properly so I was looking to see if there were any reductions I could utilize before telling them to scrap the old design.

I have been using a safety factor of 5 based on OSHA's guidelines for wire rope, shackles, etc. However, during my research I found the offshore standard (DNV-OS-H205) allows for a different safety factor on the "lift points" than for the rigging. First, does anyone know of a resource that provides a safety factor of less than 5? More subjectively, should the padeye be treated the same as the wire rope and shackle? There shouldn't be as much wear on the padeye as on the wire rope and shackle so it seems to me like the safety factor should be lower.

Thank you in advance for you answers,

ah

 

[ChadV]

Depends on where you are, but I'd think ASME BTH-1 should be applicable.

 

[dik]

Mines Act if used over the hoistway requires a SF=10.

Dik

 

[CANPRO]

Agreed that ASME BTH-1 is probably your best bet. Safety factors vary depending on the failure mode you're checking and the service class, but I believe all factors are less than 5.

Side question - if you're not sure what factor of safety to use or which code is governing your situation, how are you sure the padeyes were not designed properly? I don't know all the details obviously, but try not to pass judgement on the other engineers design until you have a chance for a thorough review.

 

[AlexH15]

Thank you for the responses! I read through ASME BTH-1 and it is suitable for my situation.

CANPRO,

The previous engineer checked the padeye weld for shear only and didn't include moment induced by eccentricity. Essentially, his calculations were not checking the correct failure mechanisms. However he used a safety factor of 4 (instead of 3 which is allowed by BTH-1) so they ended up being satisfactory but for the wrong reasons.

ah

 

[dik]

Once they yield, they behave elastically.

Dik

 

[JStephen]

Note that BTH is applicable to lifting devices, not to the load itself. It is in a convenient form that it CAN be used for parts of the load, but that doesn't mean that you're obligated to use the BTH factors when designing the load.