RIGGING SAFETY GUIDE

Proper Rigging for Mechanical Construction and Service

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Experienced mechanical construction and service workers are experts in pipefitting, plumbing, or mechanical service work, but not necessarily in rigging. However, many of these workers perform rigging as a part of their regular work routine. Therefore, they do need some knowledge in safe rigging practices for the types of rigging they perform on a regular basis. Additional knowledge or refresher information on some of the key safe rigging practices provided by this guide will help these workers:

• Prevent rigging/lifting related injuries;
• Prevent damage to equipment, materials and property; and
• Perform their rigging responsibilities more effectively.
  This guide is intended to help the user include safety in the planning and actual practice of rigging mechanical industry equipment and materials for lifting operations.

Introduction

The three main parts to any load lifting operation are the lifting equipment (crane/derrick/hoist), the operator/operation of the equipment, and the rigging of the load. This guide focuses on the rigging of the load. Specifically, it addresses how mechanical construction and service workers can safely rig the types of loads that are most common in our industry.

This guide does not cover all there is to know about rigging. While most mechanical construction and service workers are not rigging experts, many of them become skilled at safely rigging the materials and equipment used in the mechanical industry.

Ten basic rules for safe mechanical industry rigging operations are described in this guide. By learning the basic concepts behind each rule and following the rules while participating in mechanical industry rigging operations, mechanical industry riggers will help keep themselves and others in the work area safe from rigging related hazards.

Basic rigging safety for routine lifts in mechanical construction and service industry applications are covered in this guide. Critical lifts are not routine lifts and require considerable professional expertise in lifting equipment, operation of the equipment, rigging, and critical lift planning. Critical lifts may include, but are not necessarily limited to lifts involving multiple cranes, lifts over operating facilities, lifts close to power lines, lifts that exceed the designated percentage of the rated capacity (usually between 70% and 80%), lifts over occupied buildings, etc. Before participating in the rigging of a critical lift make sure that:

• A critical lift plan designed specifically for the critical lift that you will be involved with has been developed by a properly trained/qualified person;
• The most senior supervisor in charge of the lift, the equipment operator and the lead rigger have approved and signed off on the critical lift plan; and
• Your supervisor has verified that you are properly trained and qualified to participate in the critical-lift rigging process.

This guide is not intended to provide exhaustive treatment on the subject of crane, derrick and/or hoist rigging operations as they pertain to the mechanical construction and service industry. Further, it is not intended to provide legal advice. Employers must make independent determinations regarding the need for legal assistance.

Table of Contents

• Rule #1—Determine the Weight of the Load
• Rule #2—Determine Proper Hitch Based on Load Type
• Rule #3—Understand Angles & Tension on Slings/Hardware
• Rule #4—Select the Right Sling Based on Load Type
• Rule #5—Select the Right Hardware for the Load
• Rule #6—Inspect Each Sling Before You Use It
• Rule #7—Inspect Rigging Hardware Before You Use It
• Rule #8—Protect Slings from Cuts and Tears
• Rule #9—Determine the Load’s Center of Gravity
• Rule #10—Pay Close Attention to Detail at Lift Time
• Appendix A—Safety Tips for Common Industry Rigging Applications
• Appendix B—Pre-Lift Reminders for Riggers
• Appendix C—Hand Signals for Crane Operations

Rule # 1—Determine the Weight of the Load

The rated capacities of cranes/derricks/hoists and rigging equipment are of little practical use if you do not know the weight of the load that is to be rigged and lifted. In some cases it will be rather obvious that the load is too light to exceed lifting and rigging equipment- rated capacities. However, there will be cases when you are uncertain whether the load can be lifted safely. That is when you need to establish the weight of the load and compare it to the rated capacities of the lifting equipment, sling or slings, and rigging hardware. Here is how to determine the weight of the materials most commonly rigged for lifting in the mechanical industry.

Pipe

Pipe weights are standardized by material and wall thickness. Manufacturers often paint the weight per foot on the pipe making weight calculations simple. You can also use pipe charts when they are available, but when necessary, calculate the weight of steel pipe by using the formula below. If there are multiple pieces of the same size and type of pipe, remember to multiply the weight of one piece by the total number of pieces. For various sizes/types of pipe, calculate the weight of each piece and add them together.

Weight of Steel Pipe = Pi x D x L x T x (Unit Weight)

In the following example, we will calculate the weight of a single piece of steel pipe.

| Key | What It Means | Illustration | |--------------|----------------------------------------| | Pi | 3.14 | 20L375I3O490 pounds cu. ft. | | D | 3 feet | | | L | 20 feet | | | T | .03125 feet (.375 inches divided by 12)| | | Unit Weight | 490 pounds cu. ft. | |

Weight of Steel Pipe = Pi x D x L x T x (Unit Weight)

HVAC Units/Equipment

In some cases the weight will be listed on the equipment. Otherwise obtain the weight from the manufacturer or supplier. Request the specifications of the equipment in writing and confirm that they match the brand and model number of the equipment to be rigged.

Pumps, Fans, Welding Machines, Boilers, and Miscellaneous Equipment

Check the specifications provided by the manufacturer or supplier for the weight of the object or objects. If that information is not available at the jobsite, contact the manufacturer or supplier and give them the brand and model number of the equipment. Request the specifications in writing and confirm that the specifications match the brand and model number of the equipment that will be rigged/lifted.

Compressed Gas Cylinders

Determine whether the cylinders are empty or full and multiply the number of cylinders by the proper weight. Remember to add the weight of the cage to the total weight of the cylinders.

Typical Cylinder Weight Examples

These are sample weights and should not be used for your load weight calculations. Obtain cylinder weights from your supplier. Also, be sure to use approved cylinder handling cages/devices when lifting compressed gas cylinders.

Rule # 2—Determine Proper Hitch Based on Load Type

A rigging hitch is used to attach the sling to the load. There are three basic types of hitches: the vertical hitch, choker hitch, and basket hitch. It is critical that the hitch you select will safely support the load.

For example, a single choker hitch would not provide full support for a stack of loose pipe. When the lift starts and the sling tightens, it would become taut around the bottom and sides of the stack, but the pipe on top of the stack would remain loose. A much safer choice for a stack of loose pipe would be a 2-sling double wrap choker hitch or a 2-sling double wrap basket hitch, which would secure the pipe for lifting.

The illustrations on the following pages show the proper applications for hitches that are commonly used in our industry.

Rule # 3—Understand Angles & Tension on Slings/Hardware

One of the most important things to remember about sling tension is that the lower the angle between the load and the sling, the higher the tension on the sling. Angles also increase the tension on hardware. Hardware’s rated capacity decreases when it is pulled from any direction other than vertical. This is critical information for proper sling and hardware selection and proper use.

Sling Angle/Tension Examples

905 pounds of force per sling

Continuous reduction in percentage of rated capacity as the angle increases. Check with the manufacturer for details.

517 pounds of force per sling

100% of Rated Capacity

Continuous reduction in percentage of rated capacity as the angle is increased and load moves out from center of hook.

100% of Rated

Multi Leg Slings

Be sure to consider the number of legs on multi leg slings when determining sling tension and rated capacity.

• Each leg of a two leg sling shares the load.
• Each leg of a three leg sling shares the load.
• On a four leg sling only two of the legs may be carrying the majority of the load. The other two legs balance the load.
• Make sure the rated capacity of each sling is adequate for the load.

2-Leg Slings Share the Whole Load

3-Leg Slings Share the Whole Load

4-Leg Slings: 2 Legs Carry Most of the Load

Rule # 4—Select the Right Sling Based on Load Type

There are several different types of slings to choose from. The slings used most frequently in the mechanical industry are synthetic web slings, synthetic round slings, wire rope slings, and alloy steel chain slings. A critical consideration in sling selection is the relationship between the rated capacities of the sling and the type of hitch you plan to use. The rated capacity of a sling used with a vertical hitch will be different if you use the same sling with a choker hitch or a basket hitch. For example:

Synthetic Round Sling

Rated capacities for a specific brand and model of synthetic web sling:

Wire Rope Sling

Rated capacities for a specific brand and model of wire rope sling:

Rule # 5 – Select the Right Hardware for the Load

Selecting the right hardware for each specific rigging application is just as important as selecting the right slings. Hooks, shackles, eyebolts, and U-bolt wire rope clips are among the most frequently used rigging hardware in our industry. While there are several different types of hardware in these categories, the selection process is the same for hooks, shackles and eyebolts. They are rated based on straight, linear tension. Be aware that the rated capacity changes when angles are involved just like it does when using slings. When selecting hardware for a particular application ask yourself:

1. Do the design and composition of the hardware make it strong enough to perform the work safely (rated capacity)? When asking yourself this question, remember to consider reductions for hardware that will be used in angular situations.
2. Will the hardware keep the load secure?
3. Is the hardware compatible with the sling?
4. Is the hardware in good condition?
5. Could the hardware damage the materials or equipment that is to be rigged/lifted?

General

• Capacity tables should be used only for pre-project planning purposes.
• Rated capacities of the same sizes and types of hardware may be significantly different from one manufacturer to another. For example, the rated capacity of a 7/8” eyebolt made by one manufacturer may be several hundred pounds different than the rated capacity for a 7/8” eyebolt made by a different manufacturer.
• When selecting hardware, always use the rated capacity provided by the manufacturer specifically for that piece of hardware.

Rule # 6—Inspect Each Sling Before You Use It

Rigging slings wear out over time and become dangerous when they can no longer safely support their rated capacity. Sling inspections are critical and should be performed before each use.

Procedure for Handling Defective Equipment

• When you come across a defective sling destroy it immediately in accordance with our company policy.
• If you are not sure whether any part of the sling is safe to use, do not use it. Put a “Danger Do Not Use” tag on it and take it out of service until a properly trained/qualified person can inspect it and determine whether it is safe to use.

Synthetic Web Slings

INSPECTIONS

• Look for permanently attached identification on each sling. The information should include the manufacturer’s name or trademark, the manufacturer’s code number or stock number, the rated capacities based on the three basic types of hitches, the angles on which the capacities are based, the type of core material that makes up the sling, and the type of cover material, if different than the core material.
• Carefully inspect synthetic web slings inch by inch to ensure that any damaged areas are identified.
• Check for melting or charring that would indicate exposure to excessive heat or flames, rendering the sling defective.
• Look for cuts, tears, snags or any other fiber damage, which would render the sling defective.
• Carefully observe the stitching throughout the sling looking for broken and worn stitching, which would render the sling defective.

Appendix A—Safety Tips for Common Industry Rigging Applications

Sling Safety Tips
Never tie two or more slings together. Always connect two slings with a shackle.

Never attach a sling directly to a lifting lug. Be sure to choke below the threads on
synthetic web slings.

“Never saddle a dead horse.”
The saddle always goes on the “live” end of the wire rope.

Hook Safety Tips
Be sure to use the right size sling for the size of the hook.

Appendix B—Pre-Lift Reminders for Riggers

• Check the weather conditions before the lift. If the weather is extreme, postpone the lift.
• Make sure you have good communication in place with the lift equipment operator.
• Check the area for power lines and other obstructions.
• Wear a hardhat and sturdy work gloves when rigging.
• Rig the load so that it will be lifted straight up, which will help prevent the load from swinging.
• Guide the operator to place the boom directly over the load, which will help prevent the load from swinging.
• Make sure your hands are clear of pinch points when the sling starts to tighten around the load.
• Watch carefully when the lift starts in case the load does swing.
• Be sure to stay out from under the load when it is being lifted and moved.
• Use one or more tag lines to control the load.
• Make sure the receiving area is firm, flat, and free from loose objects that could fly up when the load is delivered. And, make sure the area is free from other obstructions.
• Signal the operator to deliver the load slowly.
• Guide the load onto the blocking so that it will not be dislodged.
• Watch the placement of your feet when you receive the load.
• Give the stop signal immediately if something does not appear to be safe.

Appendix C—Hand Signals for Crane Operations

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