Connecting means for fall protection systems are divided into four main sections. Snap hooks, carabiners, lanyards and shock absorbing lanyards. In this section we are going to examine each of these connector types so that the employee will have a better working knowledge of the equipment available and it’s use.
1.5.1 Snap Hooks
In the past non-locking snap hooks have been the rule however, as of January 1st, 1998 OSHA requires self – locking snap hooks to be used. The use of self – locking snap hooks reduces the probability of accidental roll out (disengagement of connectors) however, there is still the possibility of a forced roll out disengagement especially if the connectors are improperly used, mated or poorly maintained.
ANSI requires that the hooks be either drop forged, stamped or machined from high tensile steel, proof tested to 3,600 lbs and are capable of withstanding a 5,000lb-impact force. A quality hook should have its rating, country of origin and either in writing or by symbol a drop forged manufacture notation. While the hook itself is rated for 5,000 lbs it should be important to note that the weakest point of the hook is the gate. Side gate loading of the device is dangerous when you consider that only 350 to 400 pounds of impact force is needed to ” blow” the gate.
Snap hooks come in various designs and it is crucial that the hook be user friendly in all types of environments and weather conditions. Hooks that are easy to use in mild conditions may be found to be difficult to open with a gloved hand while others may tend to jam up if not cleaned on a regular basis.
Other types of hooks available are ladder or scaffold hooks. While these types offer larger mouth openings and are very easy to open, there is always the possibility of accidental unlocking of the hook if the device becomes wedged between the employee and a work surface. Some snap hook variants incorporate integral swivels which allows for an attached lanyard to align itself eliminating the possibility of twisting the lanyard or cross gate loading if the hook is connected to an eye bolt.
Inspection, Care, and Maintenance
Hooks should be inspected by the end user on a per use basis. Deformations, cracks, burrs, discoloration and improper alignment of the gate should be notated and the hook retired. Broken springs or excessive slop in the gate would also mandate retirement of the device. Hooks exposed to harsh environments such as acids and metal particulate contamination and are subject to heavy use where they are dropped or banged against machinery are prime candidates for early replacement. Note: On some occasions workers have compromised hooks by grinding out the locking mechanism or merely taping the lock open. Not only is this dangerous but borders on the criminal if the hook is being used by someone unaware that the hook has been “altered”. Further, many times a hook sewn into a shock-absorbing lanyard has been involved in a fall, taken out of service then cut from the lanyard and used for other purposes. This is poor practice. There is no practical avenue to determine whether that particular hook’s capabilities have been compromised. Once a hook is involved in a fall, identify and destroy.
Keeping a hook clean is a simple affair. Gates should be cleaned with WD-40 or similar type solvent, then cleaned with a soft, dry clothe. Greases or oils may lubricate but if not completely removed have a tendency to attract dirt. Lubrication can be accomplished with a dry lubricant such as graphite. Again, consult the manufacturers recommendations if unsure as to the correct process for the appliance.
Carabiners by definition are connector components comprised of an oval, elliptical or trapezoidal shaped body with a normally closed gate that may be opened to permit the body to receive an object. In the case of OSHA approved devices the gate must be self-locking. ANSI does not recognize non-locking types. In the recent past manual or screw gate carabiners were accepted however, there were legitimate concerns on the advisability of using these devices in the workplace. Fire and rescue personnel are still allowed the use of screw gate carabiners for rescue purposes since OSHA does not specifically address rescue services or equipment.
Carabiners have their origin in mountain climbing and the earliest versions were in steel, then aluminum. All were non- locking to allow for quick access and egress of the climbing rope however care and attention was needed to ensure that roll out did not occur as it did many times because of negligence or oversight.
Screw Gate or Manual Lock Carabiners
The need to have a secured carabiner led to the screw gate carabiner, a device that requires the user to manually screw or lock the carabiner. The carabiners were available in either aluminum or steel. The major concerns over using these types centered on proper loading of the device and the whether an employee could be counted on to lock the device each and every time. Other problems arose when the device was exposed to continuous vibration and would occasionally “unlock” itself. In other cases, under load the carabiner would stretch and the screw gate slip down. When the load was released in would be almost impossible to unlock the device by hand.
Auto – Locking Carabiners
In response to the concerns with the screw gate types auto – locking carabiners were introduced. These devices could be opened with one hand and when the sleeve was released, would lock without any further assistance. Since the gate did not have to be screwed shut these carabiners would not jam closed after a load was not released nor would they open because of excessive vibration. Loading or proper positioning of the carabiner ceased to be a concern since the device would load itself along its spine. There is one cautionary the user should be aware of, if the sleeve of the carabiner is allowed to come into close contact with clothing, harnesses and equipment the sleeve may be forced open effectively unlocking the carbine.
Aluminum vs. Steel
There has been a continual debate over the use of these two materials. OSHA allows for the use of aluminum by stating that the connector can be made of ” materials of equivalent strength.” The controversy over aluminum stems from the question of durability and whether aluminum carabiners could sustain an impact from height without compromising their tensile or impact strength ratings. On the question of durability steel wins out. Steel carabiners are capable of absorbing a tremendous amount of wear and tear and continue to function. Dropping them or having them tossed into tool bins is not recommended but the reality is this is the type of treatment most of the devices are subject to. Admittedly, aluminum is not as durable as steel but on the question on their ability to absorb impact it appears that the concern is not over the body of the carabiner but rather the sleeve.
If the carabiner is dropped any deformation of, or difficulty opening and closing of the gate would be the criteria for removal of the device from use. From the industrial standpoint steel, auto – locking carabiners are still the best choice.
Cross Gate Loading
Although this condition has been mitigated by the self-loading design of modern industrial carabiners employees should be aware of the possibility and it’s consequences. This condition is exemplified by the carabiner being loaded across it’s gate rather than along it’s axis or spine. A carabiner that is rated at 5,000lbs along its spine is rated at less than half the rating when cross gate loaded. This condition can be caused by having too many slings in the carabiner or having the load rotate and catch the sleeve of the carabiner.
Types of Carabiners:
The basic designs for industrial use can be reduced to three basic types.
- The standard D
- The Offset D
The major point of the D type carabiners is the great strength that this device is capable of. They are also prone to load properly which relates to less probability of cross gate loading.
The scaffold type carabiners are much larger and have large mouth openings some as wide as 2 inches. This allows workers to secure them to larger structural members that their smaller cousins cannot do. These scaffold carabiners are available in three shapes, pear, triangle, and offset triangle. Another type would be a captive eye with a swivel designed to allow full movement of the worker without twisting the lanyard. These carabiners rarely exceed the 5,000lb rating because of the pin that has been drilled into the spine to allow the 360-degree movement however, if used properly these devices are extremely versatile especially if used with self-retracting lifelines.
The minimum rating for carabiners is 5,000lbs. Most will exceed these ratings however, one should be careful and read the rating that is stamped on the device. There are carabiners that are rated at 3,600lb and these do not fulfill the OSHA requirements.
Inspection, Care and Maintenance
Inspection of carabiners should be done on a daily basis. Carabiners that have significant dents, gouges discoloration, improper alignment of the gate or gates that are stiff and difficult to open or close should be taken out of service. Carabiners involved in falls should also be removed and destroyed with the view that if allowed to be used for other purposes there is always the possibility of catastrophic failure of the device. Like snap hooks, carabiners should be serviced with a dry lubricant and cleaned with a soft, dry cloth.
The ANSI definition of a lanyard is as follows: A component consisting of a flexible line of rope, wire rope or strap which generally has a connector at each end for connecting the body support to a fall arrestor, energy absorber, anchorage connector or anchorage. (ANSI Z359.1)
Lanyards are typically three to six feet in length however; some lanyards are adjustable in length and in some specialized applications may be as much as 12 feet in length. OSHA only allows a maximum free fall of six feet for the vast majority of industries. The major exception would be those people involved in the erection of steel.
Other types of lanyards that are available would the dual lanyard that is actually two lanyards attached to a specially designed shock absorber. This type would be used as a 100% tie off for those workers moving in a horizontal direction while involved in their work tasks.
There are three basic types of lanyards, based on the materials used for their construction.
Laid Rope: This type was the most common until the introduction of the synthetic, web style lanyard. It consisted of three strands of nylon with a minimum total diameter of 1/2 inch. The nylon construction gave this type high strength and elasticity. The downside of a nylon lanyard was its propensity to absorb water and thus loose up to 30% of its strength while wet. With the laid rope construction, foreign material such as grit, sand, and any type of particulate matter could find it’s way in between the strands and so degrade the lanyard from the inside out. Nylon also did not fare well in the areas of hot work or where there was exposure to corrosives or acids.
Flat Synthetics: These types of synthetics are very strong and compare very favorably with nylon and unlike nylon are not affected by rain or water. They have high resistance to abrasion but are, like nylon, suspect around areas of high temperature, hot work and corrosive exposure. Another factor to consider with synthetics is UV degradation. Leaving them exposed for long periods to strong sunlight has a detrimental effect on their strength and durability. Synthetics also have very little in the way of elasticity.
Stainless Steel and Galvanized Cable: This type of lanyard is usually found in very unique work areas. High strength, excellent abrasion resistance, and affected by only the most extreme temperatures. They are used in welding, hot work and any type of environment that would be hostile to the other types. One caution would be in the area of electrical work for obvious reasons. One point to keep in mind, these types have no elasticity.
Along with these three there is a fourth type commonly referred to as a manyard. This type incorporates an internal shock absorber within the nylon core of its construction. While very popular because of it’s relatively lightweight and absence of a pouch – type shock absorber there are concerns with this style. There are variants on the market that show impact on the lanyard but do so in reverse. The Miller Manyard and the DBI product exemplify this problem, which operate exactly the same with the exception of their impact indicators. Mixing these lanyards is apt to cause confusion even if personnel are highly trained in their use.
All the lanyard types previously described with the exception of the manyard should be used in conjunction with a shock absorber, preferably one that is integrally attached to the lanyard. Cable lanyards, if used in a fall protection system should always be used in conjunction with a shock absorber!
The reason is the amount of impact force that can be generated on a human body during a fall. Medical studies show that the human body cannot sustain impacts of 2,500lbs and above. Tests have shown that dropping a 220lb test weight six feet can generate as much as 6,000 lb. of impact if a steel cable is used and 2,800 lb. with a flat web synthetic. Nylon lanyards generated between 1,700 and 1,900lbs of impact force due to nylon’s elastic capabilities. Even so, OSHA mandates that the maximum impact force that a worker can be exposed to is 1,800lbs while wearing a full body harness. The inconsistency of a nylon lanyard mandates the use of a shock absorber if the lanyard is part of a fall protection system.
One of the most common abuses of lanyards is girth hitching, which is tying the lanyard back onto itself by utilizing the snap hook. Many times workers will use this method to tie themselves off. This is an extremely dangerous practice because of the pressure being exerted against the gate of the snap hook. While discussing snap hooks we noted that the gate of the hook could only sustain 350 – 400 lb. worth of force. Further, the amount of pressure being exerted against the lanyard material itself could cause the material to break even if it’s steel cable. There are now devices with an integrated shock absorber that will allow for tie offs but these use steel D-ring sewn directly to the lanyard itself. We will examine this type and other variants in the next section.
Inspection, Care, and Maintenance
Lanyards should be routinely inspected for cuts, tears, abrasions and discoloration. Brown or black spots in flat synthetic webbing may be indicative of splatter burns from grinding or welding work. Discoloration may stem from UV degradation or exposure to chemicals. Laid rope lanyards should be inspected inside and out. Opening the weave to see if the lanyard has grit, stones or other foreign matter that may degrade the interior portion of the lanyard. In cable lanyards fraying of the cable, or signs of excessive wear at the point of connection with the hook or the shock absorber would dictate removal of the lanyard from service. Synthetics that may be unusually stiff or soft may indicate exposure to petroleum products such as gasoline, diesel fuel, turpentine or kerosene. Lastly, any lanyard that has seen service for any other reason other than fall protection should be taken out of service for that purpose and so labeled or if it has seen an impacted fall it should be removed and destroyed.
1.5.4 Shock Absorbers
Shock absorbers or as referred to by ANSI, energy absorbers, is a component whose primary function is to dissipate energy and limit deceleration forces imposed on the body during fall arrest. A personal energy absorber is one that is attached to the harness.
There are three basic types of energy absorbers defined by their construction. One is made of flat webbing folded over on itself and stitched in a pattern that upon activation will break the stitching in a controlled manner thereby dissipating the energy.
The second form is a woven pattern with a designed fault that upon activation will tear the material up the middle at set rate of speed.
The third is a loomed effect; this type has often been referred to as the “Velcro effect” in that when the materials that have been loomed together tear apart during a fall, the remaining material appears to have a Velcro type appearance.
The fourth type of absorber was discussed in the previous section. This is the Manyard style, which has a woven interior that will tear out at a pre-determined rate. An additional problem with manyard style absorbers is they look like simple lanyards and may be used as such by those who are not trained in their use.
Energy absorbers should meet or exceed ANSI standards. Section 5.3 of the ANSI standard should be read and reviewed by those whose task it is to purchase and maintain fall protection equipment. NOTE: When purchasing energy absorbers read the manufacturers label closely. Energy absorbers manufactured for the Canadian market will allow maximum elongation of forty-eight (48) inches; those manufactured for the U.S. market will have a maximum tear out of forty-two (42) inches. Energy absorbers for both markets will appear to be identical from external appearances; you cannot use Canadian style energy absorbers in the U.S. All energy absorbers must have the ability to support 5,000 pounds after they have been activated. Which means even after they have been fully deployed to their full extent they must be able to support the above quoted weight. If they do not they will not meet the standard and should not be used. NOTE: Energy absorbers are required to limit the amount of impact force to the worker to 900 pounds. Most, if not all, will keep well below that number.
Energy absorbers can be purchased in a variety of ways. The most common is an energy absorber integrated into a six-foot lanyard. Others are sewn to three and four foot lengths to accommodate worker requirements. There are versions that have twelve-foot lengths however, these have been specifically designed for the steel industry and should only be used by those properly trained in their use. Others are integrated directly into the harness, which has merit because this ensures that workers will have the availability of the absorber immediately. It also reduces the possibility of girth hitching the lanyard. There are products on the market that allows girth hitching but these use steel rings sewn directly into the lanyard that allow the hook to secure to the ring and have reinforced areas of the lanyard to allow it to wrap around the selected anchor point.
Another type is the 100% tie off which is two equal length lanyards integrated into an energy absorber that has been so designed and engineered that upon activation, even if both lanyards are secured at different lengths, the tear out will be equalized so the worker will not be subjected to unequal or excessive impact.
Inspection, Care, and Maintenance
The decision to retire and energy absorber from service rests on a number of issues.
- Length of service. If the absorber has been well taken care of and has seen little in the way of abuse then between five and seven years will be the rule of thumb. Again, check with the manufacturer. The products produced today are much better than products produced five years ago.
- Check for tears, cuts abrasions and discoloration of the synthetic material of the lanyard.
- Deformation and damage to the energy absorber pouch. Damage in this area may impede the workings of the absorber and may even indicate a partial activation of the device. Remember: The amount of force to begin activation of the energy absorber is rated at 450 pounds. A partial fall may tear out a very insignificant portion of the device however, at this point the absorber MUST be removed from service and DESTROYED!
- Examine the hardware for burrs, deformities and proper operation. These include the hooks and ring if so equipped.