Modifying Rigging Components & Arrangements
Frequently, we find ourselves receiving inquiries from companies and students with whom we've had the pleasure of collaborating in the past. As these questions populate our inboxes, we couldn't help but think: why not extend the wealth of knowledge we've accumulated and share it with others?
Do you have a question? Let us know at info@iti.com.
Here we go!
Question:
We have a person who wants to take a COTS turnbuckle JAW TO JAW and replace the pin/nut/cotter pin on one end of the turnbuckle system with an SS quick release ball lock pin. They do plan to proof load the rigging prior to use. Is this an acceptable practice, or should there be an analysis done that shows the SS quick release ball lock pin has the same properties as the pin they are replacing?
I have not run across ball lock pins being in the load path as a bearing surface in shear before. Does OSHA or ASME allow for this type of modification?
Answer:
The replacement part(s) must be approved by the original turnbuckle manufacturer, or a qualified person, if your organization wishes to adhere to ASME guidelines concerning any rigging component replacement (ASME B30.26-2.8).
A common failure mode of turnbuckle jaws, if subjected to overload, is for the center of the load pin to deform towards the force forming into an arc. This action causes the ears of the jaw, to splay outward, putting significant force on the bolt head, and the nut (or in this case, the pin head, and the spring ball in the quick release ball lock pin).
The quick release pin has a hollow cylinder in the middle of the pin axis, that permits actuation of the spring ball, when you push the thumb plunger. The spring ball is a retainer, and not really a load bearing resistor, like a nut. Both of these represent concerning features of the component for your specific application.
We would suggest to by-pass the qualified person, and go straight to the turnbuckle manufacturer for a response.
ITI’s Rigging Inspection Training Courses train and qualify your people to inspect, maintain, purchase, replace and manage your rigging equipment. Learn more at www.iti.com/courses/rigging-inspection.