Pitting and Corrosion

Bills photo

ASME B30.26-2015 Chapter 26-1 Shackles

26-1.8: INSPECTION, REPAIR AND REMOVAL26-1.8.5 Removal Criteria states:

“Shackles shall be removed from service if conditions such as the following are present and shall only be returned to service when approved by a qualified person:”…

“(c) excessive pitting or corrosion”…

“(g) incomplete pin engagement”…

 

photo 2

What Is Pitting & Corrosion?

Pitting is an extremely localized form of corrosion on metal which produces small holes or cavities. Corrosion or rust (iron oxide) is the end result when metal in the form of a shackle is exposed to moisture and oxygen for extended periods of time. The main catalyst for corrosion is water.

What Are You Inspecting?

In the two pictures you will note the results of pitting and corrosion on a screw pin shackle. The pin and ears of the shackle have formed an ionic bond. Alternately, extensive iron oxide has accumulated on the threads of the screw pin and the grooves of the ears so that the pin can no longer engage with the ears of the shackle. Note how far the shoulder of the screw pin is from the ear of the shackle.  To reiterate pin engagement is no longer possible.

Always inspect your rigging before you use it. When you come across a shackle with pitting, corrosion, or poor pin engagement, put that shackle out of service and stay safe.

Follow Bill Teichgraber @rigging_guy on Twitter & Instagram.