From boats and ships to a variety of industrial lifting applications, shackles are the primary connecting device in any rigging system. They are perfect for use with lifting slings and tow ropes in any material handling job.
A shackle is a U-shaped piece of metal made from galvanized or stainless steel with a quick release clevis pin or bolt mechanism.
Like all other types of rigging equipment, shackles require regular inspections and maintenance to ensure safe and efficient use. If you don’t inspect shackles regularly, you might face deadly accidents as a result.
That’s why the American Society of Mechanical Engineers (ASME) has created standards for selection, use, and maintenance rigging hardware, with the B30.26 Rigging Hardware section focusing on shackles, among other lifting equipment.
In this post, we will take a look at the critical factors you should look for when visually inspecting shackles before every use.
1. Pin and Body Identifications or Shackles
One of the first things you should check for is pin and body identifications/markings. The ASME standards require that every manufacturer provide the necessary identifications and markings on the body and pin of each shackle.
- Body: The markings on the body tell you about the manufacturer (trademark or name), rated load limit, and the size of the shackle. These markings are forged, cast, or die-stamped on the body.
- Pin: The pin markings also tell you about the manufacturer and rated load limits, along with the grade and type of the material used to make it. They are also forged, cast, or die-stamped on the pin.
Before starting any material handling task, make sure to check the shackles for identifications and markings. If these markings are missing, you won’t be able to know the rated capacity of the shackle.
If the load you attach is more than the rated capacity, it can result in fatal accidents. So, if these specifications are missing or illegible, you should replace the shackle right away.
2. Damage to the Shackle’s Original Shape
If any shackle is more than 10% worn out of its original shape, it is deemed unsafe for use. You can visually inspect each shackle before use to check if there is an elongation or wear of the shackle eye and pinholes. Elongation usually indicates that the shackles had been subject to overloading. If you see any of these signs, discard the shackle immediately.
3. Excessive Corrosion and Pitting
Pitting is a localized form of corrosion, commonly found in all metal shackles. Usually, pitting and corrosion take place if the shackles get exposed to moisture and oxygen for a longer period. The process of pitting produces small holes or cavities in the metal, making the shackles unsafe for lifting applications even within the rated load limits.
The threads of the screw pin and the grooves of the ears of a shackle are the most common areas for finding pitting and corrosion. The corrosion prevents the pin from fastening with the ears of the shackle properly, making it unsafe for use.
Check these areas carefully before each use. If you find any signs of pitting, remove the shackle from use immediately.
4. Other Shackle Deformations
Shackles are also susceptible to other forms of physical distortions, and may be bent, twisted, stretched, sagged, and cracked load-bearing components. These damages may become more prominent with age and excessive use.
Check the body, the pin, and the pinholes carefully. You should never try to repair bent, cracked, or twisted shackle components. The only safe option is to remove the damaged shackle from use.
5. Heat Damage to Rigging Shackles
At the time of manufacturing, shackles are subjected to heat treatment. The process involves using extreme chilling or heating temperatures to harden or soften the shackle material, per the desired requirements. This process plays a critical role in determining the elongation and duration of the shackles.
However, when the shackles are exposed to heat in the field, the process can be reversed, distorting the shackles. A few signs may indicate potential heat damage, including, blue or straw discoloration of the shackle material.
Alternatively, when welding spatters, which are essentially molten dots of metal, fall on a shackle, their heat gets transmitted to the shackle immediately. This heat exchange can harm the physiological properties of a shackle. Check for these damages before each use.
How Frequently Should You Inspect Shackles?
Regular inspection is required by law when it comes to material handling and rigging devices like shackles. You will need to perform the following three types of inspections to ensure safety and performance.
- Initial Inspection: You need to perform this inspection when you purchase new shackles or get old ones altered/repaired. Have an experienced, certified professional conduct these inspections.
- Before Use Inspection: Every time you want to use a shackle, you need to inspect it visually. If you find any distortions, you need to replace the shackles immediately.
- Periodic Inventory Inspection: Apart from these, you need to check your inventory of shackles once every year. In this inspection, you will need to evaluate factors like the frequency of shackle use, environmental conditions, the nature of the loads, and the duration of use.
Shackles play a critical role in various rigging and material handling applications across a wide range of industries. Using shackles without a thorough safety check before each use can be dangerous.
Hopefully, the above checklist will help you make sure that each shackle you are using is not only safe but also efficient.
For information on rigging shackles, lifting equipment, and other pieces of hardware, talk to our experts at Holloway Houston Inc. We’re standing by to ensure your devices are safe and thoroughly inspected.