scaffolding wire rope free sample

Two-point adjustable suspension scaffolds, also known as swing-stage scaffolds, are perhaps the most common type of suspended scaffold. Hung by ropes or cables connected to stirrups at each end of the platform, they are typically used by window washers on skyscrapers, but play a prominent role in high-rise construction as well.

Each suspension rope, including connecting hardware, must be capable of supporting, without failure, at least 6 times the maximum intended load applied to that rope while the scaffold is operating at the greater of either [29 CFR 1926.451(a)(4)]:

Suspension ropes supporting adjustable suspension scaffolds must have a diameter large enough to permit proper functioning of brake and hoist mechanisms. [29 CFR 1926.451(f)(10)]

Wire suspension ropes must not be joined together except through the use of eye splice thimbles connected with shackles or coverplates and bolts. [29 CFR 1926.451(d)(8)]

The load end of wire suspension ropes must be equipped with proper-size thimbles, and secured by eyesplicing or equivalent means (Figure 8). [29 CFR 1926.451(d)(9)]

Ropes must be inspected for defects by a competent person prior to each workshift, and after every occurrence which could affect a rope"s integrity (see Tip). [29 CFR 1926.451(d)(10)]

Six randomly distributed wires are broken in one rope lay, or three broken wires in one strand in one rope lay (Figure 11). [29 CFR 1926.451(d)(10)(iii)]

Loss of more than one-third of the original diameter of the outside wires due to abrasion, corrosion, scrubbing, flattening, or peening. [29 CFR 1926.451(d)(10)(iv)]

Swaged attachments or spliced eyes on wire suspension ropes may not be used unless they are made by the manufacturer or a qualified person. [29 CFR 1926.451(d)(11)]

When U-bolt clips are used, the U-bolt must be placed over the dead end of the rope, and the saddle must be placed over the live end of the rope. [29 CFR 1926.451(d)(12)(vi)]

Suspension ropes are to be shielded from heat-producing processes. When acids or other corrosive substances are used on a scaffold, the ropes shall be shielded, treated to protect against the corrosive substances, or shall be of a material that will not be damaged by the substances. [29 CFR 1926.451(f)(11)]

Tip: Analysis of Bureau of Labor Statistics data for suspended scaffold fatalities from 1992-99 found that over 20 percent of fall deaths were due to suspension ropes breaking. This underlines the importance of inspecting ropes before every workshift.

When winding drum hoists are used and the scaffold is extended to its lowest point of travel, there must be enough rope to still wrap four times around the drum. [29 CFR 1926.451(d)(6)]

When other types of hoists are used, the suspension ropes must be long enough to allow the scaffold to travel to the level below without the rope end passing through the hoist, or else the rope end must be provided with means to prevent the end from passing through the hoist. [29 CFR 1926.451(d)(6)]

Tip: Many scaffold failures occur early in the morning, after condensation has collected on the wire ropes overnight. The preferred industry practice at the beginning of a shift is to raise the scaffold 3 feet, hit the brakes, then lower the scaffold and hit the brakes again. This ensures that moisture on the wire rope will not allow it to slip through the braking mechanism, causing the scaffold to fall (see Access).

Tip: When a suspended scaffold sits overnight, water condensation may form on the wire ropes, making them slip through the braking device and cause the scaffold to fall. Before allowing workers onto the platform, a good safety practice is to raise the scaffold 3 feet, then lower it and hit the brakes to clear the moisture (see Support).

When lanyards are connected to horizontal lifelines or structural members, the scaffold must have additional independent support lines and automatic locking devices capable of stopping the fall of the scaffold in case one or both of the suspension ropes fail. These independent support lines must be equal in number and strength to the suspension ropes. [29 CFR 1926.451(g)(3)(iii)]

Tip: Almost all incidents that involve scaffold failure would not lead to fatality or serious injury if proper personal fall-arrest systems were in use. Hence, such incidents almost always involve two violations: One that causes the scaffold to fall, and the other when workers fail to use (or their employers fail to provide) appropriate safety harnesses, lanyards, lifelines, etc.

Two-point suspension scaffolds shall not be bridged or otherwise connected one to another during raising and lowering operations unless the bridge connections are articulated (attached), and the hoists properly sized. [29 CFR 1926.452(p)(5)]

Suspended scaffolds are often made of metal and sometimes used in close proximity to overhead power lines. These factors introduce the risk of electrocution. However, proper clearance and maintenance reduce this risk.

When welding is being performed from suspended scaffolds, the following precautions must be taken, as they apply, to reduce the possibility of welding current arcing through the suspension wire ropes [29 CFR 1926.451(f)(17)]:

An insulated thimble must be used to attach each suspension wire rope to its hanging support (such as cornice hook or outrigger). Excess suspension wire rope and any additional independent lines from grounding must also be insulated. [29 CFR 1926.451(f)(17)(i)]

Six other boilermakers had just left a suspension scaffold when it fell about 392 feet along with the foreman, who was killed. The superintendent had ordered the scaffold"s main support be disassembled before the scaffold was lowered to ground level. Rigging, welding machines, materials and supplies, etc., were placed on the scaffold, and two 1-inch wire rope hoist lines were cut free. This put the load on a single ¾-inch wire rope hoist line, which was overloaded by 255 percent, and on the diesel hoist located outside the chimney, which was overloaded by 167 percent. The superintendent was in a rush to get the system disassembled because a helicopter had been contracted to remove the structural members of the scaffold support system on Monday.

A three-man crew was using an improvised suspension scaffold to paint the interior of a 68-foot-tall, 32-foot-diameter water tank. The scaffold consisted of an aluminum ladder used as a platform, and secured to steel "stirrups" made of steel bar stock bent into a box shape and attached to each end of the ladder. Wire cables from each stirrup ran to a common tie-off point. A cable from this common tie-off was rigged to a block-and-tackle used from ground level to raise and lower the platform. The block-and-tackle supporting the system was secured to a vertical steel pipe on top of the tank by a cable, which was fashioned into a loop by U-bolting the dead ends of a piece of wire rope.

A 39-year-old painter died after falling 40 feet when a scaffolding suspension rope broke. He was a member of a three-man crew engaged in the abrasive blasting and painting of the interior of a 48-foot-high, 30-foot-diameter steel water tank. At the time of the incident, the victim was standing on an outer end of the scaffold platform and was pulling on the suspension rope to raise that end of the scaffold. He fell when the rope broke and his end of the platform dropped to a vertical position. The victim was not using personal fall protection equipment, although it was available and was being used by a second painter. An investigation revealed that the ⅝-inch hoist rope broke at a point where it had been burned some time before the incident.

Two victims and a co-worker were painting the side of a building in San Francisco. They were on a two-point suspension scaffold that did not have guardrails; the ropes suspending the scaffold were old and had not been inspected; and the employees were not wearing safety belts. When the left scaffold rope broke and the scaffold collapsed, one employee was killed and another fell to a nearby roof and broke both arms. The co-worker was left hanging on to the remaining scaffold rope.

Three workers were on a two-point suspension scaffold rated at 500 lbs. working weight. As the employees went up in the scaffold, the right side fell to the ground from an elevation of 20 feet. One worker managed to hold on, the other two fell with the scaffold, resulting in one worker dying and the other being hospitalized for extensive injuries. Investigation indicated that the scaffold motor assembly was improperly connected to the scaffold platform. The workers were wearing the available safety harnesses and lifelines but had not connected the lifelines.

Two employees, the leadman and a trainee mechanic, were assigned to move a two-point suspended scaffold equipped with two SC40 hoists. They lowered the scaffold from the top roof some 16 feet to a small intermediate roof. The plan was to lower the scaffold an additional 20 feet to the main roof. After approximately two feet, the right-side hoist unit stopped. The employees thought that the overspeed brake had accidentally set. The leadman--the competent person on site--got out of the scaffold onto the roof and worked with the trainee to manually override and release the overspeed brake. This was done without inspecting the hoist for sufficient cable length. The right side hoist had only been set up with enough cable to go from the upper roof to the intermediate roof, a total of 16 feet (the total cable length measured 18 feet 5½ inches). When the brake was released, the three inches of cable left on the drum ran out and the hoist fell, causing the right side of the scaffold to drop. The trainee fell 18 feet, landed on a stored scaffold pick, and was lucky to sustain only a chipped ankle bone and a bruised calf. The company did not conduct a fall protection or competent person inspection, nor was a safety line or any fall protection used. The hoist worked as designed, but the wire rope safety device was manually overridden.

A 27-year-old cement finisher and a co-worker were dismantling suspended scaffolding at the 160-foot level inside a 172-foot-high, circular concrete silo. Both men were wearing safety belts with nylon rope lanyards secured to independent lifelines. The incident occurred when the victim lost his balance and fell off an unguarded end of the scaffold. The co-worker stated that he saw the victim fall and jerk upward as the lanyard caught him. When the victim"s weight dropped back on the lanyard, it snapped, allowing him to fall to his death on a concrete floor. Examination of the lanyard after the event showed burn damage at several places, including the point of failure. The employer did not control inspection or distribution of this fall protection equipment. Instead, the equipment was kept in a common supply bin where the workers could readily obtain it when needed and return it when work was completed. The lanyard had been returned to the storage bin even though it had probably been damaged earlier during cutting and welding operations.

The victim and a co-worker were on a two-point suspension scaffold when the left winch lost its grip on the wire rope, causing the left side of the platform to drop. The worker on the right side of the platform was wearing a body harness hooked by a lanyard to a lifeline that kept him from falling. The victim was on the left side of the platform and was wearing the same equipment, but he apparently did not have the lanyard hooked to his lifeline. He fell eleven floors and was killed.

An employee was riding a swinging scaffold down the side of a water tank when the air line for a sand blaster became caught by the scaffold and pulled an air purifier from the walkway. The purifier struck the employee and knocked him from the scaffolding. He was not wearing his safety belt and was killed.

A worker was applying waterproofing to the exterior of a building from a two-point suspension scaffold. Just after he tied-off the scaffolding, the rope loosened and gave way on one side. According to witnesses, the worker slipped out of his safety belt and fell three floors to a concrete walkway and injured his head. He was pronounced dead on arrival at a hospital at 11:55 a.m.

At approximately 2:00 p.m., a painter and a helper were scraping, glazing, and painting windows from a 32-foot-high two-point suspension scaffold. The employees stopped painting because it started to rain. They pulled ⅞-inch manila hoisting ropes up to the work platform and laid them over the top of the guardrail system at both ends of the 19-foot-long scaffold platform. The painter sent the helper to the sidewalk below to receive the tools and paint buckets. While lowering the materials to his helper, the painter was thrown from the scaffold platform when the platform tipped over. He died. The employees were not using fall protection, and the scaffold was not tied off.

Two laborers were working on a motorized two-point suspension scaffold, 70 feet above ground level, without safety belts, lanyards, or lifelines. An "eye" formed by three wire rope clips, which connected the wire rope to the C-hook, failed to hold, and one end of the scaffold came down. One employee fell to the ground, and the second employee at the other end was catapulted through an open window, where he was pulled to safety by office workers. Two of the rope clips were still attached to the end of the rope after the incident. The third clip fell to the ground, and was found to have stripped threads.

An employee was arc welding from a suspended scaffold. The work lead on the welder had frayed insulation in one place, and the bare conductor was exposed. The frayed section of welding cable was tied around the metal guardrail of the scaffold. Since the scaffold was not grounded, it became energized. This caused arcing between the scaffold and the building. The welding current passed through the wire rope supporting the scaffold, and the wire rope separated. The employee and the scaffold fell 50 feet to the ground. The employee was hospitalized for his injuries.

Re: Wire rope clips on suspension scaffolds; safety latches on large crane hooks; hanging scaffolds - order of assembly; jobsite fabricated lifting accessories - criteria; and horizontal lifelines: use of wire rope clips, anchorages, number of persons allowed to be connected, requirements relating to sag, and use of synthetic rope.

Question 1(a) - (c): When using horizontal lifelines as part of personal fall arrest systems, what type of wire rope clips does OSHA require, and how many clips must be used? Additionally, what are the horizontal spacing criteria for the uprights?

Subpart M does not specify what type of wire rope clip or how many clips/clamps must be used when installing a horizontal lifeline. However, under §1926.502(d)(8), these decisions must be made under the supervision of a qualified person when the system is designed. The determination of the horizontal spacing criteria for uprights is also left to the qualified person"s supervisory approval.1

In an August 28, 2000 letter to Mr. Troxell2, we addressed the related issue of using wire rope clips on a wire rope guardrail. In that letter, we cautioned that, as a practical matter, it is unlikely that the criteria requirements for guardrails under §1926.502(b) could be met unless the manufacturer"s recommendations for the number of clips to be used on wire ropes of different diameters were followed (for example, the Crosby Group, Inc., general catalog 2000 edition, has tables showing their recommendations for their clips). We also pointed out that OSHA"s standard for rigging equipment used for material handling, 29 CFR 1926.251, has a table showing the number of clips required for wire rope ½-inch and greater. We noted that although that standard does not apply to wire rope used for guardrails, when designing a rope system to meet the §1926.502 guardrail requirements, following the tables at §1926.251 will normally ensure that there will be enough clips.

Question 2: For a horizontal lifeline used as part of a personal fall arrest system during steel erection work, how tight should the lifeline be, and may synthetic rope be used for the horizontal lifeline?

With regard to the use of synthetic ropes, §1926.502(d)(14) specifies that, when using non-wire rope, synthetic rope (rather than nature fiber rope) must be used:

Section 1926.451(f) sets out requirements involving the use of the scaffold. Where scaffolding is erected, moved, dismantled, or altered, §1926.451(f)(7) provides:

Question 5: Under §1926.451(d)(12)(v) and (vi), when wire rope clips are used on suspension scaffolds, "(v) U-bolt clips shall not be used at the point of suspension for any scaffold hoist," and "(vi) when U-bolt clips are used, the U-bolt shall be placed over the dead end of the rope, and the saddle shall be placed over the live end of the rope." Does §1926.451(d)(12)(v) contradict paragraph (d)(12)(vi)?

No. By its terms, §1926.451(d)(12)(v) prohibits the use of U-bolt clips at the point of suspension for any scaffold. The scaffold standard does not prohibit using U-bolt clips elsewhere. However, when using them elsewhere, under §1926.451(d)(12)(vi), the U-bolt must be placed over the dead end of the rope, and the saddle placed over the live end of the rope.

Question 6: Under §1926.251(c)(4)(iii), are eyes in wire rope bridles and slings or bull wires formed by wire rope clips permitted when used to lift scrap boxes or pendants?

This provision specifically prohibits eyes in wire rope bridles and slings or bull wires being formed by wire rope clips. There is no exception for lifting scrap boxes or pendants.

In our view, the industry recognizes that the following engineering factors, among others, must be considered when designing horizontal high-lines: the span and sag of the wire rope line, the weight of the load being lifted, the initial tension of the rope line, and the size of the columns.

Knotting wire rope compromises the integrity of the strength of the wire rope and is therefore prohibited. Based on the picture provided, which showed a knot in wire rope secured by a U-bolt clip, this practice would be in violation of §1926.251(c)(3).

Rope Services Direct supplies a variety of anti-spin non rotating wire rope (also called rotation resistant wire-rope). All standard rope wirehas a tendency to develop torque and therefore prone to rotation, whereas non-rotating wire ropes are designed so that the wire-rope outer rotational force naturally counteracts the inner strands rotational force. This is in the event that a rope is subjected to a load.

Rope elongation and rotation occurs on standard ropes when loaded, which can therefore spin the load, quite possibly out of control, which can be dangerous. When the rope rotates in this way the strands will begin to unravel. This causes the rope to lose strength and will undoubtedly fail, which could be catastrophic. It is for these reasons that non rotating wire rope is commonly used for many types of lifting applications including main hoist rope, whip rope,crane rope, off-shore and deck rope and more.

Non rotating wire rope or rotation resistant wire rope has a different construction to standard. as wires and strands are not laid in the same direction like they would be on standard rope. Inner and outer strands of wires are laid in opposite directions. For example the inner may be constructed in left hand lay whilst the outer layer is in right hand lay. The nature of this construction means that torsional forces on the inner and outer wires/strands will counteract each other and therefore minimising the risk of unraveling.

It is worth noting that the number of strand layers will have an effect of the resistance of rotation. A 2 layer rope has less resistance than a 3 layer rope. Therefore the more layers the rope has the greater rotation resistance it will have.

These types of ropes can be classified as spin resistant, rotation resistant or non rotation resistant. Classed on the basis of the number of rotations a certain length of rope does when a force of 20% of the MBF is applied; with 1 turn or less the rope will be classified as non rotating; with rotations between 1 & 4 the rope is classed as low rotation and for rotations between 4 & 10 the rope will be classified as spin resistant, any higher and the rope is NOT rotation resistant at all.

Correct usage and care with handling will prolong the working life. This is due to the friction on the inner wires caused by the strand crossover’s which will eventually cause the inner wires to break up. This is more apparent on non rotating wire rope with two layers. Ropes with 3 or more strand layers will distribute the radial pressures more evenly. Which will reduce friction and stress on the inner wires.

Regular,thorough inspectionsof non rotating rope are essential due to the fact that it is the inner strands that often break first and broken internal wires often go unnoticed as they are difficult to see.Rope Services Direct offer inspectionson all rope with certification issued on completion.

Holding both ends of the rope will prevent unraveling. Correctly fitted terminations will help to prevent damage. Kinking and unraveling may occur and they can also have an effect on the rotational balance if not fitted correctly.

Application1.Elevator wire rope;Avation wire rope;Fishing wire rope;Aerial ropeway &cable car wire rope;Wire rope for drill deep equipment;telecommunications, barrier etc