Update:Proper Use Of Screw Pin Bow Shackles

[Dave]

As long as I can remember (I started logging in 1989…), the instruction for the screw pin bow shackle has been to fully engage the pin to the body, then back off the pin an eighth to a quarter turn. The purpose and intention was to avoid locking the pin to the body of the shackle when loading the pin.

We must continue to adapt to new standards.

Overhead rigging has new guidance documented by The American Society of Mechanical Engineers. ASME B30.26-2015 26-1.9.4 (a) The screw pin threads shall be fully engaged and tight, and the shoulder, should be in contact with the shackle body (see Fig. 26-1.9.4-1)Should the pin become secured to the body; use of an adjustable spanner wrench, spud tool, or screw driver can be utilized to loosen the pin.

 

[Herbie]

Fair enough. I'm guessing ASME has concerns about vibration- or shock-induced backout on the pin threads.

This is good incentive for everyone to keep their gear clean, dry, and lightly oiled too - the least little bit of rust will make that connection a much bigger plain to unthread.

 

[Celt II]

I've always snugged my pins hand tight before putting a load to them. Guess they finally have to come round to my way of thinking....