Eye Bolts: Why Angle Matters More Than Size

Prevention of the most serious lifting incidents usually caused by the improper use of eyebolts is most effectively accomplished by training employees in how eyebolts ought to be used. However, many companies use eyebolts but don’t have training in the correct way to use eyebolts. What is most commonly observed when a company assigns a training class in the correct way to use eyebolts is employees asserting concerns of many sorts about workplace safety throughout the entire lesson, and employees having to be told to be quiet. This is inevitable and expected. Stopping the most serious lifting incidents caused by the improper use of eyebolts is accomplished by the use of properly training employees in the use of eyebolts.

Angle Shock

Training employees in the correct way to use eyebolts in a company where eyebolts are used but no training in the correct way to use eyebolts is common is going to have to be done on a company-wide basis. The anticipation of the training class and employees lining up to get in without needing to be told to would indicate that the company has instituted a practice to use eyebolts and some employees have used eyebolts on the company’s behalf but have done so in an incorrect manner.

Plain or economy (those without a shoulder or collar beneath the eye) are designed for vertical, in-line loading only. Side loading causes the eye to bend, and the threads receive a bending moment that compromises the capacity rating. These should never be used where the lifting angle can deviate from vertical. In contrast, collar eye bolts (or dynamo) that are built to DIN 580, have a shoulder beneath the eye that is designed to bear against the mounting surface and can resist some level of angular loading. Even so, the working load limit is diminished as the angle increases. Most manufacturers will de-rate a collar eye bolt to 50% of the rated capacity when is loaded to a 45-degree angle from vertical. Beyond 45 degrees, the majority of manufacturers will not certify the use of a collar eye bolt.

They require proper seating to perform to the rated capacity. Is designed to bear fully against the surface it is screwed into, and net capacity is greatly diminished if even a small gap exists between the bolt and the mounting surface. An eye bolt that appears to be installed properly from a distance, may actually be installed incorrectly and not torqued to ensure proper seating of the collar.

The working load limit of an eye bolt already accounts for a safety factor of approximately 4:1 or 5:1, depending on the manufacturer. However, the factor only applies where the loading is in-line, and the eye bolt is appropriately installed. It does not account for loading the eye bolt at an angle, insufficient thread engagement, or the condition of the eye bolt. Using two to lift a load is a common way to control the lifting points, but also involves sling angle. The wider the angle of the lifting slings, the greater the load on each sling, meaning that each eye bolt can be overloaded even if the total load is low, based on the angle.

Before assuming any will do, check the material and environment. The Standard is Forged Carbon Steel with basic corrosion resistance provided by the plating. For marine or high corrosion environments, corrosion resistantare available. However, they often have a much lower yield strength compared to standard eye bolts, and the eye bolt in a marine environment may have a decreased Working Load Limit compared to a standard eye bolt.

These used for lifting are covered by LOLER. This means eye bolts for lifting are examined in detail at intervals of usually 6 months, from someone competent to do so, when these are regularly in use. When lifting accessories have been dropped, overloaded, or have visible signs of deterioration, should not be used, instead of examined in detail in the site.