U.S. Department of Labor

Occupational Safety and Health Admistration

Directorate of Science, Technology and Medicine

Office of Science and Technology Assessment

This Safety and Health Information Bulletin is not a

standard or regulation, and it creates no new legal

obligations. The Bulletin is advisory in nature,

informational in content, and is intended to assist

employers in providing a safe and healthful workplace. The Occupational Safety and Health Act

requires employers to comply with hazard-specific

safety and health standards. In addition, pursuant to

Section 5(a)(1), the General Duty Clause of the Act,

employers must provide their employees with a

workplace free from recognized hazards likely to

cause death or serious physical harm. Employers

can be cited for violating the General Duty Clause if

there is a recognized hazard and they do not take

reasonable steps to prevent or abate the hazard.

However, failure to implement any recommendations

in this Safety and Health Information Bulletin is not,

in itself, a violation of the General Duty Clause.

Citations can only be based on standards, regulations,

and the General Duty Clause.

Purpose

The purpose of this Safety and Health Information

Bulletin is:

1. To alert concrete panel manufacturers that finger

rack storage systems for concrete panels need to be

designed with sufficient capacity and strength to

prevent panels from tipping over;

2. To encourage the development of installation and

storage procedures; and

3. To encourage employers to provide training

concerning, and to enforce work rules regarding, the

installation and storage procedures.

Background

The Denver Area Office investigated a fatal accident

involving the tip over of concrete panels stored in

finger racks at a concrete panel manufacturing

facility. The concrete panels are flat panels of

various sizes and thickness and are commonly used

as concrete sound barrier walls or as reinforced

concrete retaining walls. The panels generally are

not strong enough to be stored flat, and therefore

they are commonly stored in an upright position

using finger racks or other storage systems.

Finger Rack Storage System

The finger rack system involved in the accident was

built with two horizontal steel tubes about 80 feet

long with 1.25 inch diameter holes spaced along the

tube length. The top tube (6-inch square) was

supported about 5.25 feet above the ground surface

using the same size steel vertical tubing and diagonal

braces. The second tube (4-inch square) was

similarily secured about midway between the top

tube and the ground surface.

After the panels are manufactured and partially

cured, they are stored in the panel racks for

additional curing time until ready for shipment. The

panels are hoisted into the racks for storage using a

forklift or a crane. When positioned in the finger

racks, the panels may or may not be supported

underneath by wooden members (dunnage) to level

the panels. The panels are positioned close to the

finger rack (typically within 1⁄2-inch) and held in a

nearly upright position using 20-inch-long, number 7

Safety and Health Information Bulletin

02-10-2004

Precast Concrete Panels-Hazardous Storage
rebar pins that are inserted into the finger rack holes

(see figure 1). A single pin can be used on both

sides of the finger rack such that the pin is normally

positioned to extend out only about 6-7 inches on

each side of the square tube. Wooden wedges, of

variable widths and thicknesses, are positioned and

hammered between the panel and the pins to further

secure the panel in an upright position.

The pins used at the site were made of grade 60

billet steel (60-ksi yield strength). Some of the pins

used were bent, indicating that they were

undersized. The pins did not have any retaining

mechanism to prevent the pins from being pushed

through the tube holes or for ensuring the pins were

inserted the proper distance.

Incident Description

On the day of the accident, all the panels in the rack

tipped over which resulted in the collapse of the

entire system (80 feet long). While all of the factors

that caused the panels to tip over have not been

identified, there were no wind or weather conditions

that would account for the tip over. Two employees

were instructed to secure panels in the other racks.

Approximately three hours after the first tip over,

one of the two employees was fatally injured when

five panels tipped over. The panels involved in these

collapses were typically 12 feet high by 8 inches

thick, varied in length from 23 feet to about 25.5

feet, and weighed over 13 tons each.

Other Information

The accident investigation revealed that the panel tip

overs were partially due to the inadequate design of

the finger rack system and to improper storage

procedures for the size and configuration of the

panels involved. The finger rack was installed and

being used without any engineering design that

specified the rack capacity and procedures for its

use. The rack system should have been properly

engineered to prevent tip over in order to ensure the

safety of the personnel around the stored panels and

to prevent damage to the panels.

Recommendations

Employers should ensure that finger racks are

designed with sufficient strength for the safe storage

of concrete panels and are used in accordance with

their design. Some methods to improve rack

stability include:

1. Increase the diameter and/or strength of the

rebar pins such that they are less subject to

permanent bending during use.

2. Place dunnage under each and every panel in at

least two locations (each within two feet of each end

of the wall panels) to help prevent twisting motions

that could cause the panel to tip and/or cause the

wedges to come loose.

3. Include specifications, such as the size, thickness,

and length of the steel horizontal restraining

members. They should be rigidly attached to the

rack.

4. Secure the wedges to the pin to prevent them

from falling out.

5. Include an additional tier rack near the top of the

panels to provide additional support (see figure 2).

6. Design the pins so that they are of a consistent

size and shape to ensure proper placement during

installation (see figure 3), and that they are also

restrained from horizontal displacement once

installed. One way of restraining movement would

be to install a clevis pin.

7. Include additional holes in the rack to minimize

the movement of the panels between the pins and

minimize the number and sizes of the wedges

needed (see figure 2).

8. Design the system and implement installation

procedures such that if one panel tips over it does

not cause adjacent panels to tip over.

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9. Do not perform patching/finishing work on the

panels while stored in the rack. Such activity should

be performed in a separate area, where adequate

support is provided for the additional stress that may

be involved.

10. Mark the racks conspicuously to indicate design

capacities (e.g. height, length and weight of panels).

11. Establish, communicate, and enforce proper

storage procedures.

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Figure 1. Finger rack with inadequate rebar pin holding panels.

12. Ensure a professional engineer reviews and

provides specific requirements (specifications) for

the storage system and storage procedures of

concrete panels.

 Also the pin is not properly placed
 

Figure 2. Higher tier finger rack.

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Figure 3. Different types of pins.