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The Safety Harness  E-mail

 

History of Current and Proposed Fall Protection/Safety Harness Regulations:

 

OSHA Compliant Fall Protection

• General duty clause – public law 91-596, December 1970

• General industry – proposed 1990

• Construction industry - 1995

• Scaffolds - 1996

• Steel erection – January 2002

 

 

Personal Fall Protection Systems

These systems must include 3 elements referred to as ABC:

A - Anchorage - a mechanical system fixed to the structure - such as a Horizontal Life Line

B - Body Wear - a full body safety harness worn by the worker

C - Connector - a subsystem connect the anchorage to the harness - such as a lanyard

Without all of these elements, there is not a complete system and the protection technique cannot be used.

 

Energy Absorption

To arrest a fall in a controlled manner, it is essential that there is sufficient energy absorption capacity in the system. Without this designed energy absorption, the fall can only be arrested by applying large forces to the worker and to the anchorage, which can result in either or both being severely effected.

An analogy for this energy absorption is to consider the difference in dropping an egg onto a stone floor or dropping it into soft mud. Even for the same fall distance and weight of egg (the input energy), there will be more damage with the stone floor as the arrest distance is smaller and so forces must be higher to dissipate the energy. For the soft mud, the arrest distance is longer and so arrest forces are lower but the egg is still stopped and is hopefully undamaged.

Most fall protection anchorages are designed on the basis that all workers will have a connector which includes an energy absorber. Hence, when using such systems, it is essential that the PPE used is rated for Fall Arrest and includes an energy absorber.

A common form on anchorage device for a safety harness is an HLL (Horizontal Life Line). These are linear anchorage devices, which allow workers to move along the whole length of the anchor, usually without needing to disconnect and fixing points of the anchorage.

It is normally essential to include energy (or shock) absorbers within HLL in addition to those within the workers' PPE. Without such absorbers, the horizontal life line cannot deform significantly when arresting the fall. This in turn results in large resolved forces being generated within the anchorage safety system, which can readily be sufficient to cause failure of the anchorage system. This can occur even with energy absorbers being included in the PPE of the worker.

 

Fall Clearance

In arresting a fall in a controlled manner the distance required to arrest the fall must be considered. This is a function of the "fall factor" and the deployment of the "energy absorbers". As a rule of thumb for a factor 2 fall, a fall distance of approx 6 feet will be required. This is equivalent to 2 storys of a building. If the fall clearance is less than this the worker may strike the ground before his fall is arrested.

 

Design of HLL Systems

This is a complex process. The designer should always perform a design calculation and the results of this calculation should be presented in any proposal and verified as acceptable. The loads applied to the structure and the fall clearance required should be verified for employee security.

 

Calculating Fall Clearances:

C=H-X+L+D+K
X=Height of anchor point above standing surface
H=Height of D-ring on persons body harness
L= Length of lanyard
D=Deceleration distance
K=The stretch factor for the system
Maximum arresting force is 1800 pounds

 

FALL PROTECTION
INFORMATION
(from the US Dept. of Labor OSHA website)  
 

Fall Protection Categories

All fall protection products fit into four functional categories. 1. Fall Arrest; 2. Positioning; 3. Suspension; 4. Retrieval.



Fall Arrest
A fall arrest system is required if any risk exists that a worker may fall from an elevated position, as a general rule, the fall arrest system should be used anytime a working height of six feet or more is reached. Working height is the distance from the walking/working surface to a grade or lower level. A fall arrest system will only come into service should a fall occur. A full-body harness with a shock-absorbing lanyard or a retractable lifeline is the only product recommended. A full-body safety harness distributes the forces throughout the body, and the shock-absorbing lanyard decreases the total fall arresting forces.

Positioning
This system holds the worker in place while keeping his/her hands free to work. Whenever the worker leans back, the system is activated. However, the personal positioning system is not specifically designed for fall arrest purposes.

Suspension
This equipment lowers and supports the worker while allowing a hands-free work environment, and is widely used in window washing and painting industries. This suspension system components are not designed to arrest a free fall, a backup fall arrest system should be used in conjunction with the suspension system.

Retrieval
Preplanning for retrieval in the event of a fall should be taken into consideration when developing a proactive fall management safety program.

Fall Protection Systems

Listed below are different types of fall safety equipment and their recommended usage.
Class 1 Body belts (single or double D-ring) are designed to restrain a person in a hazardous work position and to reduce the possibility of falls. They should not be used when fall potential exists; positioning only.
Class 2 Chest harnesses are used when there are only limited fall hazards (no vertical free fall hazard), or for retrieving persons such as removal of persons from a tank or a bin.
Class 3 Full body harnesses are designed to arrest the most severe free falls.
Class 4 Suspension belts are independent work supports used to suspend a worker, such as boatswain's chairs or raising or lowering harnesses.
Rope Lanyard Offers some elastic properties for all arrest; used for restraint purpose.
Web Lanyard Ideal for restraint purposes where fall hazards are less than 2 feet.
Cable Positioning
Lanyards		 Designed for corrosive or excess heat environments and must be used in conjunction with shock absorbing devices.
Shock Absorbers When used, the fall arresting force will be greatly reduced if a fall occurs.
Rope Grabs A deceleration device which travels on a lifeline, used to safely ascend or descend ladders or sloped surfaces and automatically, by friction, engages the lifeline and locks so as to arrest the fall of an employee.
Retractable Lifeline Systems Gives fall protection and mobility to the user when working at height or in areas where there is a danger of falling.
Safety Nets Can be used to lesson the fall exposure when working where temporary floors and scaffolds are not used and the fall distance exceeds 25 feet.
Rail Systems When climbing a ladder, rail systems can be used on any fixed ladder as well as curved surfaces as a reliable method of fall prevention.


Effective January 1, 1998, body belts are not acceptable as part of a personal fall protection system. (Note: the use of a body belt in a positioning device system is acceptable and is regulated under paragraph (e) of 29 CFR 1926.502). An employee who uses a body belt as a personal fall arrest system is exposed to hazards such as falling out of the belt, serious internal injuries, and technical asphyxiation through prolonged suspension.

Inspection and Maintenance

To maintain their service life and high performance, all belts and harnesses should be inspected frequently. Visual inspection before each use should become routine, and also a routine inspection by a competent person. If any of the conditions listed below are found the equipment should be replaced before being used.

Harness Inspection
1. Belts and Rings: For harness inspections begin at one end, hold the body side of the belt toward you, grasping the belt with your hands six to eight inches apart. Bend the belt in an inverted "U." Watch for frayed edges, broken fibers, pulled stitches, cuts or chemical damage. Check D-rings and D-ring metal wear pads for distortion, cracks, breaks, and rough or sharp edges. The D-ring bar should be at a 90 degree angle with the long axis of the belt and should pivot freely.

Attachments of buckles and D-rings should be given special attention. Note any unusual wear, frayed or cut fibers, or distortion of the buckles. Rivets should be tight and unremovable with fingers. Body side rivet base and outside rivets should be flat against the material. Bent rivets will fail under stress.

Inspect frayed or broken strands. Broken webbing strands generally appear as tufts on the webbing surface. Any broken, cut or burnt stitches will be readily seen.

2. Tongue Buckle: Buckle tongues should be free of distortion in shape and motion. They should overlap the buckle frame and move freely back and forth in their socket. Rollers should turn freely on the frame. Check for distortion or sharp edges.

3. Friction Buckle: Inspect the safety buckle for distortion. The outer bar or center bars must be straight. Pay special attention to corners and attachment points of the center bar.

Learn more about Fall Safety Protection


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