Eyebolts Information

Last revised: February 12, 2025

Eye bolts (eyebolts) are threaded bolts with a loop or eye at one end. The eye is used to anchor a cable, rope or chain. Eye bolts are rated for different types of applications and may pivot or swivel.

Load-rated eyebolts are designed for vertical lifting, but are not recommended for angular lifting. Eye bolts that are not load-rated are designed for use with tie downs and guiding wires; however, they are not suitable for lifting applications.

Types

There are four specialized types of eyebolts.

Forged eyebolts are forged instead of formed. These one-piece fasteners that offer higher load ratings.
Screw eyes are screws with a head shaped into a loop or eye. They are often used in lifting and rigging applications, or to guide wire or cable.
Shoulder eyebolts have a shoulder under the eye. Typically, the shoulder is installed flush with the mounting surface.
Thimble eyebolts are designed with an opening that acts as a thimble for wire or rope to minimize wear.
Pivoting eyebolts are designed to pivot 180°. The base of a swiveling eyebolt is designed to swivel 360°.

Specifications

Specifications for eyebolts include:

Maximum load capacity — The maximum load which an eyebolt can handle.
Shank length — For fully-threaded eyebolts, shank diameter equals the thread length.
Threaded length
Eye inside diameter (ID)
Eye section diameter or eye thickness
Total weight

Thread Sizes

Thread sizes for eyebolts are measured in English units such as inches (in) or metric units such as millimeters (mm). Measurements for inch-based eyebolts include:

Fasteners designated as #16, #18, #20, #24 eyebolts are also available. Designations for metric eyebolts include:

As a rule, the numbers which follow the letter “M” indicate the number of millimeters in diameter. For example, an M6 eyebolt is 6 mm in diameter.

Material and Finish

Eyebolts differ in terms of material and finish. Plastic eyebolts and rubber eyebolts may be suitable for some applications. Metallic eyebolts can be made of materials including:

Aluminum
Brass
Bronze
Steel
Hardened steel
Stainless steel
Titanium
Proprietary alloys

In terms of finish, eyebolts are often anodized, galvanized, or plated with gold, silver, tin, or zinc. Black oxide is an eyebolt coating that causes virtually no dimensional change. Phosphate coatings provide corrosion resistance and a better surface for the adhesion of primers and paints. Eye bolts with zinc chromate finishes are also available.

Standards

DIN 444 — Eyebolts

ASME B18.15 — Forged eyebolts

Eyebolts FAQs

How do different types of eyebolts affect load distribution and safety in lifting operations?

Different types of eyebolts can significantly affect load distribution and safety in lifting operations. Here is a breakdown based on the types of eyebolts and their characteristics:

Nut Eye Bolts

These are threaded to structures like wood or steel posts and are supported by a hex nut. They are versatile and can be used with ropes or cables for hoisting.

The rings can be drop-forged for strength or bent into a loop for light-duty applications. The latter should not be used for heavy loads as they are not as strong.

Machinery Eye Bolts

These do not use a hex nut but are installed into tapped holes in machinery. They are designed for heavy-duty applications and can handle both vertical and angular lifts.

Proper installation is crucial to ensure safety and load distribution.

Screw Eye Bolts

Also known as lag eye bolts, these are threaded into wood or lag anchors. They are typically used for lighter applications and should not be used for heavy lifting.

Plain Pattern Eye Bolts

These are simple threaded studs with metal rings and are suitable only for vertical lifts. Angular loads can bend or break them, compromising safety.

Shoulder Eye Bolts

These are designed to handle angular loads. The shoulder helps reduce bending stress on the shank when properly fitted, making them safer for non-vertical lifts.

The working load capacity decreases significantly when the load is applied at an angle.

Safety Considerations

Load Capacity: Each type of eyebolt has a specific working load limit, which is reduced when the load is applied at an angle. For example, a stainless steel eyebolt with a 1/4 inch shank can hold up to 600 lbs vertically, but this capacity drops by about 20% at a 15° angle.

Alignment and Installation: Proper alignment with slings and correct installation (e.g., using washers and ensuring proper torque) are essential to prevent bending or breaking.

Regular Inspection: Eyebolts should be inspected for damage before each use. Any signs of wear, corrosion, or damage should lead to their removal from service to prevent failure.

What are the specific applications of different eyebolt types?

Nut Eye Bolts

Applications: These are versatile and can be used in various applications where a rope or cable needs to be fed through the ring for hoisting. They are commonly used in construction and rigging where they are threaded to structures like wood or steel posts.

Considerations: They are suitable for both light-duty and heavy-duty applications, depending on whether the ring is drop-forged or bent into a loop. The latter should only be used for light-duty tasks.

Machinery Eye Bolts

Applications: Designed for heavy-duty applications, these eyebolts are used in machinery and equipment where they are installed into tapped holes. They are suitable for both vertical and angular lifts, making them ideal for industrial settings.

Considerations: Proper installation is crucial to ensure safety and effective load distribution.

Screw Eye Bolts

Applications: Also known as lag eye bolts, these are typically used in lighter applications such as securing items to wooden structures or lag anchors. They are not recommended for heavy lifting.

Considerations: Their screw threads make them suitable for applications where they can be directly threaded into wood.

Plain Pattern Eye Bolts

Applications: These are used for vertical lifting operations. They are simple in design and are suitable for straightforward hoisting tasks.

Considerations: They should not be used for angular loads as this could lead to bending or breaking.

Shoulder Eye Bolts

Applications: These are used in situations where angular loads are present. The shoulder design helps reduce bending stress, making them safer for non-vertical lifts.

Considerations: The working load capacity decreases significantly when the load is applied at an angle, so they must be used with care.

General Safety Considerations

Load Capacity: Always adhere to the working load limits specified for each type of eyebolt, especially when dealing with angular loads.

Alignment and Installation: Ensure proper alignment with slings and correct installation to prevent bending or breaking.

Regular Inspection: Inspect eyebolts for damage before each use to ensure safety and prevent failure.

What is the importance of proper installation and alignment of eyebolts?

Proper installation and alignment of eyebolts are crucial for ensuring safety and effective load distribution during lifting operations. Here are the key reasons why these aspects are important:

Load Capacity and Safety

Eyebolts have specific working load limits that must be adhered to. Improper installation or misalignment can lead to exceeding these limits, causing the eyebolt to fail, which can result in dangerous situations or accidents.

Alignment with Slings

Eyebolts should be oriented in line with the slings. If the load is applied sideways, the eyebolt may bend or break. Proper alignment ensures that the load is distributed evenly and reduces the risk of failure.

Use of Accessories

Proper installation involves using the right accessories, such as washers and nuts, to ensure that the eyebolt securely contacts the load surface. This helps in maintaining the integrity of the lifting operation and prevents damage to the eyebolt.

Engagement of Threads

When using shims or washers, it is important to ensure that at least 90% of the threads in the receiving hole are engaged. This ensures that the eyebolt is securely fastened and reduces the risk of it coming loose during lifting.

Inspection and Maintenance

Regular inspection of eyebolts for damage, wear, or corrosion is essential. Any signs of damage should lead to their removal from service to prevent failure. This is a critical part of maintaining safety in lifting operations.

What is the impact of angular loads on the working load capacity of eyebolts?

The impact of angular loads on the working load capacity of eyebolts is significant and must be carefully considered to ensure safety and effective load distribution. Here are the key points:

Reduction in Load Capacity

Eyebolts are designed with specific working load limits for vertical lifts. When a load is applied at an angle, the working load capacity is reduced. For example, a stainless steel eyebolt with a 1/4 inch shank can hold up to 600 lbs for a vertical lift, but this capacity drops to approximately 480 lbs at a 15° angular lift, which is about a 20% reduction.

Stress on the Eyebolt

Angular loads introduce additional bending stress on the shank of the eyebolt. This is particularly important for shoulder eye bolts, which are designed to handle such stresses. The shoulder helps reduce bending stress when properly fitted, but the load capacity still decreases significantly with angular loads.

Safety Risks

Exceeding the rated load capacity due to angular loads can lead to eyebolt failure, resulting in potentially dangerous situations. It is crucial to derive the angular load capacity from the vertical load capacity and the angle of the pull to avoid exceeding the limits.

Proper Alignment

To mitigate the risks associated with angular loads, eyebolts should be aligned in line with the slings. Misalignment can cause the eyebolt to bend or break, compromising safety.

What are the safety considerations when using eyebolts for lifting operations?

When using eyebolts for lifting operations, several safety considerations are crucial to ensure effective load distribution and prevent accidents. Here are the key safety considerations:

Load Capacity

Each eyebolt has a specific working load limit, which must not be exceeded. This limit is reduced when the load is applied at an angle. For example, a stainless steel eyebolt with a 1/4 inch shank can hold up to 600 lbs for a vertical lift, but this capacity drops to approximately 480 lbs at a 15° angular lift, accounting for about a 20% reduction.

Proper Alignment

Eyebolts should be aligned in line with the slings. Misalignment can cause the eyebolt to bend or break. Proper alignment ensures that the load is distributed evenly and reduces the risk of failure.

Use of Accessories

Proper installation involves using the right accessories, such as washers and nuts, to ensure that the eyebolt securely contacts the load surface. This helps maintain the integrity of the lifting operation and prevents damage to the eyebolt.

Engagement of Threads

Ensure that at least 90% of the threads in the receiving hole are engaged when using shims or washers. This ensures that the eyebolt is securely fastened and reduces the risk of it coming loose during lifting.

Regular Inspection

Eyebolts should be inspected for damage before each use. Any signs of wear, corrosion, or damage should lead to their removal from service to prevent failure. This includes checking for nicks, bends, distortions, heavy wear, and corrosion.

Avoid Overloading

Do not exceed the rated load capacity of the eyebolts. Overloading can lead to failure, resulting in potentially dangerous situations.

What is the importance of regular inspection and maintenance of eyebolts?

Regular inspection and maintenance of eyebolts are critical for ensuring safety and reliability in lifting operations. Here are the key reasons why these practices are important:

Detection of Damage and Wear

Regular inspections help identify any signs of damage, such as nicks, bends, distortions, heavy wear, or corrosion. These issues can significantly increase the risk of failure during lifting operations.

Prevention of Accidents

By removing damaged eyebolts from service, you prevent their accidental reuse, which could lead to dangerous situations or accidents. This is especially important if there are indications of heat damage, weld splatter, arc strikes, or any alterations.

Avoidance of Hidden Damage

Eyebolts should not be painted, as paint can conceal damage during visual inspections. Instead, using stainless steel or hot-dip galvanized eyebolts is recommended for applications requiring corrosion resistance.

Ensuring Load Capacity

Regular maintenance ensures that eyebolts maintain their rated load capacity. Over time, wear and tear can reduce the load capacity, leading to potential overloading and failure.

Compliance with Safety Standards

Regular inspection and maintenance help ensure compliance with safety standards and regulations, which is essential for maintaining a safe working environment.

Eyebolts Media Gallery

References

GlobalSpec—Heat Treatment of Bolts and Fasteners for Demanding Applications

GlobalSpec—A guide to fasteners: Types of bolts, nuts, and washers

Image credits:

Te-Co, Inc.

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