wavy wire rope factory
Mechanical damage caused by the rope contacting the structure of the crane on which it is operating or an external structure—usually of a localized nature.Generally results from operational conditions.
Note—Rotation Resistant ropes are designed with a specific strand gap which may be apparent on delivery in an off tension condition. These gaps will close under load and will have no effect on the operational performance of the rope.Check sheave and drum groove radii using sheave gauge to ensure that they are no smaller than nominal rope radius +2.5%—Bridon recommends that the sheave and drum groove radii are checked prior to any rope installation.
Check if the rope has been cut “on site “ prior to installation or cut to remove a damaged portion from the end of the rope. If so, was the correct cutting procedure used? Incorrect cutting of Rotation Resistant, low rotation and parallel closed ropes can cause distortion in operation.
Wire breaks usually resulting from crushing or abrasion.Check tension on underlying layers. Bridon recommends an installation tension of between 2% and 10% of the minimum breaking force of the wire rope. Care should be taken to ensure that tension is retained in service. Insufficient tension will result in these lower layers being more prone to crushing damage.
“Pigtail” or severe spiralling in rope.Check that the sheave and drum diameter is large enough— Bridon recommends a minimum ratio of the drum / sheave to nominal rope diameter of 18:1.
Two single axial lines of broken wires running along the length of the rope approximately 120 degrees apart indicating that the rope is being “nipped” in a tight sheave.Check sheave and drum groove radii using sheave gauge to ensure that they are no smaller than nominal rope radius + 2.5%—Bridon would recommend that the sheave / drum groove radii are checked prior to any rope installation.
One line of broken wires running along the length of the rope indicating insufficient support for the rope, generally caused by oversize sheave or drum grooving.Check to see if the groove diameter is no greater than 15% greater than the nominal rope diameter.
Fatigue induced wire breaks are characterized ends by flat on the broken wires.Bending fatigue is accelerated as the load increases and as the bending radius decreases. Consider whether either factor can be improved.
Fatigue induced wire breaks are characterized ends by flat on the broken wires.Bending fatigue is accelerated as the load increases and as the bending radius decreases. Consider whether either factor can be improved.
Localized fatigue breaks indicate continuous repetitive bends over a short length. Consider whether it is economic to periodically shorten the rope in order to move the rope through the system and progressively expose fresh rope to the severe bending zone. In order to facilitate this procedure it may be necessary to begin operating with a slightly longer length of rope.
Broken rope—ropes are likely to break when subjected to substantial overload or misuse particularly when a rope has already been subjected to mechanical damage.
Corrosion of the rope both internally and/or externally can also result in a significant loss in metallic area. The rope strength is reduced to a level where it is unable to sustain the normal working load.Review operating conditions.
Wave or corkscrew deformations normally associated with multi-strand ropes.Check sheave and drum groove radii using sheave gauge to ensure that they are no smaller than nominal rope radius +2.5%—Bridon recommends that the sheave / drum groove radii are checked prior to any rope installation.
Rope accumulating or “stacking” at drum flange— due to insufficient fleet angle.Review drum design with original equipment manufacturer—consider adding rope kicker, fleeting sheave, etc.
Check tension on underlying layers—Bridon recommends an installation tension of between 2% and 10% of the minimum breaking force of the wire rope—Care should be taken to ensure that tension is retained in service. Insufficient tension will result in these lower layers being more prone to crushing damage.
Review rope selection. The smooth surface of Dyform wire ropes gives better contact with drum and sheaves and offers improved resistance to “interference” between adjacent laps of rope.
CLEVELAND, OH – Mazzella Lifting Technologies, a Mazzella Company, is pleased to announce the acquisition of Denver Wire Rope & Supply. This acquisition will strengthen Mazzella’s footprint west of the Mississippi River and reinforce Mazzella’s commitment to be a one-stop resource for lifting and rigging services and solutions.
Denver Wire Rope & Supply has been in business since 1983 and services a variety of industries out of their location in Denver, CO. Denver Wire Rope & Supply is a leading supplier of rigging products, crane and hoist service, below-the-hook lifting devices, and certified rigging inspection and training. Effective immediately, Denver Wire Rope & Supply will operate as Mazzella / Denver Wire Rope. Terms of the transaction are not being disclosed.
“Denver Wire Rope & Supply will complement the wide range of products and services that Mazzella Companies offers. We are dedicated to being a single-source provider for rigging products, overhead cranes, rigging inspections, and rigging training. Both companies commit to a customer-first mentality, providing the highest-quality products, and leading by example when it comes to safety and sharing our expertise with customers and the market,” says Tony Mazzella, CEO of Mazzella Companies.
“Our team and family are excited to be part of the Mazzella Companies. This acquisition strengthens our place in the market and allows our team to continue to provide excellent service and products to our valued customer base and expand our offering,” says Ken Gubanich, President of Denver Wire Rope & Supply.
“Over the years, we have had numerous companies show interest in purchasing Denver Wire Rope & Supply, none seemed to be the right fit. We are looking forward to becoming a part of an aggressive, passionate, and progressive organization. As a family business for over 36 years, it is important to us that our customers/friends, suppliers, and team members continue to be treated with first-class service, products, and employment opportunities. Again, we are very enthusiastic about our future and look forward to being a quality supplier for your crane, safety training, rigging, and hoisting needs for years to come,” says Gubanich.
“We wish Ed and Carol Gubanich all the best in their retirement. We welcome Ken and the other second and third-generation Gubanich family members, as well as the entire Denver Wire Rope Team, into the Mazzella organization,” says Mazzella.
We’ve changed our name from Denver Wire Rope to Mazzella. Aside from the new name and logo, our member experience is virtually unchanged. Here are some common questions and answers related to this change.
In 2019, Denver Wire Rope & Supply was acquired by Mazzella Companies to expand lifting and rigging products and services to the western half of the United States.
In 1954, James Mazzella founded Mazzella Wire Rope & Sling Co. in Cleveland, OH. For over 65 years, the company has grown organically by nurturing historic relationships, expanding its product offerings, and entering new markets through acquisition.
Abrasion damage may occur when the rope contacts an abrasive medium or simply when it passes over the drum and sheaves. Therefore it is vital that all components be in proper working order and of the appropriate diameter for the rope. A badly corrugated or worn sheave or drum will seriously damage a new rope, resulting in premature rope replacement.
Corrosion is very difficult to evaluate but is a more serious cause of degradation than abrasion. Usually signifying a lack of lubrication, corrosion will often occur internally before there is any visible external evidence on the rope’s surface. A slight discoloration caused by rusting usually indicates a need for lubrication which should be tended to immediately. If this condition persists, it will lead to severe corrosion which promotes premature fatigue failures in the wires and strands, necessitating the rope’s immediate removal from service.
The table below shows the number of allowable wire breaks per crane type. The inspector must know the ASME standard for the equipment being inspected. The number of broken wires on the outside of the wire rope is an indication of its general condition and whether or not it must be considered for replacement. The inspector may use a type of spike to gently probe the strands for any wire breaks that do not protrude. Check as the rope runs at a slow speed over the sheaves, where crown (surface) wire breaks may be easier to see. Also examine the rope near the end connections. Keeping a detailed inspection record of the wire breaks and other types of damage will help the inspector determine the elapsed time between breaks. Note the area of the breaks and carefully inspect these areas in the future. Replace the rope when the wire breaks reach the total number allowable by ASME or other applicable specifications.
Valley breaks, or breaks in between strands, must be taken very seriously at all times!When two or more valley breaks are found in one lay-length, immediately replace the rope. Valley breaks are difficult to see; however, if you see one you can be assured that there are a few more hidden in the same area. Crown breaks are signs of normal deterioration, but valley breaks indicate an abnormal condition such as fatigue or breakage of other wires such as those in the core.
Once crown and valley breaks appear, their number will steadily and quickly increase as time goes on. The broken wires should be removed as soon as possible by bending the broken ends back and forth with a pair of pliers. In this way the wire is more likely to break inside the rope where the ends will be tucked away. If the broken wires are not removed they may cause further damage. The inspector must obey the broken wire standard; pushing the rope for more life will create a dangerous situation.
It is important to check and record a new rope’s actual diameter when under normal load conditions. During the life of the rope the inspector should periodically measure the actual diameter of the rope at the same location under equivalent loading conditions. If followed carefully, this procedure reveals a common rope characteristic—after an initial reduction, the overall diameter will stabilize and slowly decrease in diameter during the course of the rope’s life. This condition is normal. However, if diameter reduction is isolated to one area or happens quickly, the inspector must immediately determine (and correct, if necessary) the cause of the diameter loss, and schedule the rope for replacement.
Crushing or flattening of the strands can be caused by a number of different factors. These problems usually occur on multilayer spooling conditions but can occur by simply using the wrong wire rope construction. Most premature crushing and/or flattening conditions occur because of improper installation of the wire rope. In many cases failure to obtain a very tight first layer (the foundation) will cause loose or “gappy” conditions in the wire rope which will cause rapid deterioration. Failure to properly break-in the new rope, or worse, to have no break-in procedure at all, will cause similar poor spooling conditions. Therefore, it is imperative that the inspector knows how to inspect the wire rope as well as how that rope was installed.
Shock loading (bird-caging) of the rope is another reason for replacement of the rope. Shock loading is caused by the sudden release of tension on the wire rope and its resultant rebound from being overloaded. The damage that occurs can never be corrected and the rope must be replaced.
High stranding may occur for a number of reasons such as failure to properly seize the rope prior to installation or maintain seizing during wedge socket installation. Sometimes wavy rope occurs due to kinks or a very tight grooving problem. Another possibility is simply introducing torque or twist into a new rope during poor installation procedures. This condition requires the inspector to evaluate the continued use of the rope or increase the frequency of inspection.
Jakob Rope SystemsJakob Rope Systems is one of the market leaders in the manufacture and supply of top-end, design-forward solutions to industrial and construction-related rope and cable applications in which elegance, simplicity and superlative quality are required.
Now, for more than a century and in over 55 countries, Jakob offers a range of steel rope products to our clients who return time and again seeking a reliable maker and provider of stainless steel wire ropes, rod fasteners, nets and unique fittings, all custom-designed and produced to fit exact specifications. At Jakob, we understand it’s the little details that make the big differences.
Every piece of finished goods leaving our warehouses is put through a stringent testing process to ensure compliance with AISI 316, ISO and DIN standards. Our cable railing, wire mesh, wire ropes, and rods can be used in multiple applications, both indoor and outdoor and at various scales, such as sign stanchions, shelving, as trellises on green walls, safety netting, and even in zoo enclosures.
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Wire Rope is an item often found on Wire Rope Cranes. Unfortunately, though these wires are not unbreakable and can/will succumb to the pressure of constant use and may potentially snap when in use. Which is why it is important to know what to look out for in an unsafe wire rope, the Government of Canada recommends a visual inspection of the wire before each use, but full inspections should be undertaken by a trained professional periodically. This article will cover what causes wire ropes to break, what your professional inspector will do to ensure your rope is safe and what you can look out for when completing your frequent inspection to ensure the rope is safe to work with.
When you hear the term wire rope you may picture in your mind a metal and seemingly unbreakable rope, and through wire ropes, can and will stand up better than many other rope types it is unfortunately not unbreakable. Some things that can cause a wire rope to break include:
Kinks caused by improper installation of a rope, sudden release of a load or knots that were made to shorten a rope can cause the rope to become compromised
Many of these causes can be minimized by the use of proper crane design and rope maintenance procedures, most of these causes though are unavoidable and are considered to be part of a normal rope life. The two main causes that are considered unavoidable are crushing and internal and external fatigue.
Many wire ropes are subject to a lot of repetitive bending over a sheave, which causes the wire to develop cracks in its individual wires. These broken wires often develop in the sections that move over sheaves. This process will become escalated if a rope travels on and off of a grooved single layer drum, which causes this to go through a bending cycle. Tests in the past have shown that winding on a single layer drum is equal to bending over a sheave because it causes similar damage.
Fatigue breaks often develop in segments as stated before these segments are usually the part of the rope surface that comes into direct contact with a sheave or drum. Because this is caused by external elements rubbing, oftentimes these breakages are external and visible for the eye to see. Once broken wires start to appear, it creates a domino effect and quickly much more will appear. Square ends of wires are common for fatigue breaks. These breaks are considered a long-term condition and are to be considered part of the normal to the operating process.
Internal Breaks,these breaks can develop over time-based upon the loading of the hoist. Many ropes are made of a torque-balanced multi-strand design, which comprises of two or more layers of strands. A torque balance is created in multi-strand ropes, by layering the outside and inside ropes in opposite directions. Multi-strand ropes offer much more flexibility and have a more wear-resistant profile. Though the wires in these ropes touch locally and at an angle, which causes them to be subject to both the effect of radial load, relative motion between wires and bending stresses when bent on sheaves or drums.
Nicking and fatigue patterns such as the ones discussed before occur in Independent Wire Rope Cores or IWRC ropes. IWRC ropes have outer wires of the outer strands, which have a larger diameter than the outer core strands. This helps to minimize inner strand nicking between the outer strands of the IWRC. The outer strands and the IWRC strands are approximately parallel. Often their neighbouring strands support these outer strands while the outer IWRC wires are relatively unsupported.
With these geometrical features it allows for the wire to fluctuate under tensile loads, the outer IWRC wires are continuously forced into valleys in between the outer strand wires and then released. This system results in secondary bending stresses which leads to a large number of core wires with fatigue breaks. These breaks are often close together and form in groups. This eventually leads to the IWRC breaking or completely disintegrating into short pieces of wire that lay, half a length long. This condition is often called complete rope core failure.
It is as the IWRC fails, and the outer strands lose their radial support then valley breaksform. Valley breaks occur when the outer strand wires bear against each other tangentially. This results in interstrand nicking, which restricts the movement of strands within the rope; without the freedom to move, secondary fatigue breaks occur in the outer strands, which will develop a stand tangent points. These breaks occur in the valleys between the outer strands hence why they are called valley breaks.
So to go over what we just learned, internal broken wires occur often in ropes that are operated with large diameter sheaves and high factors of safety. These breakages can occur when a reeving system incorporates sheaves lined with plastic or all plastic sheaves; these sheave units offer more elastic support than their steel counterparts. Which causes the pressure between outer wires and sheave grooves to be reduced to the point where the first wire breaks will occur internally.
If a section of a rope travels on and off of a grooved multi-layer drum, then it goes through what is called a bending cycle. The bending cycle occurs by a section of rope spooling in the first layer and is bent around the smooth drum surface, but when the second layer rolls around the rope section in the first layer will be spooled over. This causes the first layer to become compressed and damaged on the upper side by the second rope layer. With continued spooling the rope layers in the second and higher layers will, in turn, be damaged on both sides during contact with their neighbouring rope layers. This damage is caused both by the compression of the rope and by the rope laying on a rough surface.
Accelerated wear occurs where the point of the rope is squeezed between the drum flange and the previous layer. Often times the slap of rope at the crossover points causes peening, martensitic embrittlement and/or wire plucking, further associated rope damage is caused when the rope crosses over from layer to layer on a drum.
Also, if the lower wire rope areas where not spooled under sufficiently high tension the lower wraps can become displaced by the additional rope sections which would allow for these new rope sections to slide down in between them, which will lead to severe rope damage.
Many regulators have decided that the Statutory Life Policy be overly wasteful and they tend to use the Retirement for Clause Policy. A wire rope deteriorates slowly over its entire service, but to be aware of the state of deterioration, a wire rope must be periodically inspected. Moderate deterioration is normally present, and low levels of deterioration do not justify retirement. Which is why you have wire rope inspections to monitor the normal process of deterioration. This ensures that the rope can be retired before it can become dangerous. Besides, these inspections can detect unexpected damage or corrosion on the wire rope which will allow you to take corrective actions to ensure the longevity of the wire rope.
This system is useful for detecting external rope deterioration. To use this approach, the inspector will lightly grab the rope with a rag. The inspector then glides the cloth over the rope. Often times external broken wires will porcupine (stick up). When the rope moves along the wire it will be snagged on the broken wire. The inspectorwill then stops dragging the cloth along the wire and visually inspects the condition of the wire.
Frequently broken wires often do no porcupine, which is why a different test procedure must be utilized. This test involves moving along the rope two or three feet at a time and visually examining the rope. This method though can become tiresome because oftentimes the rope is covered in grease and many internal and external defects will avoid detection through this method.
Another method involves measuring the wire ropes diameter. This involves comparing the diameter of the current rope to the original rope’s diameter. Changes in the diameter of the rope indicate external and/or internal rope damage. This method is not perfect because many different wire breakages damages do not change the diameter of the rope.
You can also check for several visible signs of distributed losses of the metallic cross-sectional area. This is often caused by corrosion, abrasion and wear. To internally check for damage, you can insert a marlinspike under two strands and rotate it to lift the strands and open the rope.
Visual inspections are often not well suited for the detection of internal rope damage. This means that they have limited value as the only means of wire rope inspection. Though visual inspections do not require special machines. When completed by a knowledgeable and experienced rope examiner through visual inspections can be valuable tools for evaluating rope degeneration.
Electromagnetic Inspections or EM gives a detailed insight into the exact condition of a rope. EM is a very reliable inspection method and is a universally accepted method for inspecting wire ropes for mining, ski lifts and other similar industries. There are two distinct EM inspection methods, which have been developed to classify defects called Localized-Flaw (LF Inspection) and Loss-of-Metallic-Area Inspection (LMA Inspection type)
LF Inspection is similar to the rag-and-visual method. This inspection method is suited primarily for finding localized flaws, such as broken wires. Which is why small hand-held LF instruments are called electronic rags.
Electromagnetic and visual wire rope inspection methods are like peanut butter and jelly or cookies and milk they are the perfect combination, and both are essential for safe rope operation. Which is why both methods are often used to ensure maximum safety.
A program that involves periodic inspections is extremely effective. To establish baseline data for future inspections, a wire rope inspection program should begin with an initial inspection after a break-in period. Then the inspections should follow at scheduled intervals, with documentation of the ropes deterioration over its entire service life.
For multi-strand ropes often times visual inspections are ineffective which is why statutory life policy for a ropes retirement is often adopted. This means that these ropes are often discarded long before they should be meaning millions of dollars’ worth of perfectly good wire ropes are being thrown away annually.
Some people have suggested that non-rotating ropes should not be used if cranes use a single layer winding on a drum. Following this line of thought, this would mean multi-strand ropes should be used only when winding on multi-layer drums. This would cause wires to break the surface faster than internal wire damage can occur, these non-rotating wire ropes will be replaced long before internal fatigue can set in.
When internal broken wires are the problem electromagnetic rope testing can be the solution. Though there are some factors one needs to take into account such as certain regulations require rope retirement when a certain number of broken wires per unit of rope length exceed a set limit. This discard number that is specified in retirement standards refers solely to external wire breaks. This means the condition of a wire rope with internal breaks is therefore left up to the inspector.
Though you also need to take into account detailed detection and quantitative characterization of internal broken wires in ropes with many breaks and cluster breaks could be a problem. These difficulties are caused by the fact that electromagnetic wire rope can be influenced by several parameters such as:
Clusters of broken wires can cause an additional problem because the relative position of broken wires concerning each other within the rope is not known
Broken wires with zero or tight gap widths are not detectable by electromagnetic inspection because they do not have a sufficient magnetic leakage flux.
When you consider all of this you can quickly realize that you can only estimate the number of broken wires that have formed on a wire rope. You can use the LF trace for the detection of broken wires, though unfortunately it is not quantitative so it cannot be used to estimate the number of broken wires. Though it is good to note that if any internal broken wires are present an LMA trace will show rapid relatively small variations of a cross-section.
An electromagnetic inspection will help to enhance the accuracy and reliability of the inspection, by combining visual and EM methods they will be able to detect deterioration at the earliest stages. The inspections can be then used as an effective preventive maintenance tool. For example, the inspector early on detects corrosion, and you immediately apply the corrective action of improving the lubrication of the wire rope.
Wire ropes should be inspected by a certified inspector when installing it, and periodically throughout its life cycle. A wire rope should go through a quick, but thorough inspection every day that you use it at the beginning and end of each shift and you should keep records of all inspections. Ensure that your certified wire rope inspector uses a combination of visual inspection methods and electromagnetic inspection methods because this will ensure the optimum safety and longevity of the rope. This is especially true for ropes that are more likely to develop internal broken wires, and inspections completed by a certified inspector is the best way of having a preventive maintenance program and extending the life of your wire rope.
Queensland Division of Workplace Health and Safety, “Non-rotating hoist wire ropes, multi fall configurations, Health and Safety Alert,” http://www.whs.qld.gov.au/alerts/97-i-5.pdf
Verreet, R. “Wire rope damage due to bending fatigue and drum crushing,” O.I.P.E.E.C.(International Organization for the Study of the Endurance of Wire Rope) Bulletin 85, June 2003, Reading (UK), ODN 0738, pp. 27-46.
Wire ropes are largely used in marine environment or for rigging purposes. They receive considerable loads and thus suffer a great deal of mechanical damage throughout their service life. Moreover, research has shown that the major cause of wire rope failure is excessive deterioration and corrosion, lack of maintenance and inspection, and wrong usage resulting in early discarding, reduced safety and replacement cost increase.
Sometimes damage can be easily detected, while in other cases fractured wires may occur on the inside. Hence, wire ropes should be inspected and maintained by the right person (competent person assigned by the company), to assure they’re in perfect condition. Regular inspectionsensure high rope performance, long service lifetime , safety of personnel and equipment, and reduced operating costs.
All ropes (synthetic, high modulus and wire ropes) should be inspected before and after an operation. This guideline ensures maximum safety for both a ship’s personnel and equipment. Even though it’s difficult to determine the exact service life span of ropes, there is a way to have a more precise estimation about their efficient lifecycle. Calculating the exact time ropes have been in use (e.g mooring time, mooring conditions, weather and tidal conditions) is the answer. All in all, rope inspections should occur at least once a year.
Inspecting wire ropes in particular, comes with great responsibility. Inspection results should be recorded, and any defects noticed have to be reported and addressed properly. Some defects can be repaired, while in some cases replacing a wire rope is inevitable.
Periodical inspections ofvessel deck equipment is also crucial for maintaining the good condition of wire ropes. The condition of the drum, chocks, bitts, rollers, sheaves, cable clamps and other end fittings, affect the rope’s performance, threads and cords. Make sure to mark these parts during your overall inspection.
In order to help marine officers and staff conduct successful wire rope inspections – and keep an up-to-date record of them – we have created an inspection solution that helps in maintaining and monitoring a ship’s ropes and deck equipment.
When calculating mass using F = Minimum Breaking Force, according to the wire rope’s diameter, you can determine the Minimum Breaking Massand therefore the wire’s max strength. When calculating mass using F = Safe Load according to the wire rope’s diameter, you can determine the Safe Load Mass,which is the advised load for this rope diameter.
The strands of a wire rope absorb the majority of the tensile force applied on the rope. Their design and manufacturing standards affect the level of fatigue resistance and resistance to abrasion. An easy way to understand which rope design is suitable for each purpose, is the wire rope classification.
Wire ropes are classified according to the number of strands in each construction and the number of wires in each strand. For example, a classification of 6X19 means that a wire rope of this type always has six strands, but its wires could be 15-26 per strand. This is because 19 is not the exact number of wires, but the classification of a wire number range.
Visual inspections are a common and fast way to assess wire rope condition. Both the standard and rotation resistant wire rope inspectionprocesscomply with the same four steps of examination. A ship’s crew can perform them as follows:
Steel wire rope distortion is obvious in most cases and can easily be identified by the inspector or the ship‘s crew. It usually occurs if load is suddenly applied or abruptly released (shock loading), or even if swift torque is forcefully induced.
Although not all of these deformations make the rope absolutely dangerous to use, they all may cause ropes to wear unevenly in time. This means inspections should take place more often, and distorted ropes should be handled with caution.
The rag and visual inspection is a good method for regular inspection intervals. The inspector pulls a rag along the rope trying to find broken wire cords. If the rug gets snagged by the rope, the inspector has to stop and assess the wire rope’s condition. Extreme caution should be exercised during the visual inspection, and under no circumstances should this method be the only one used to inspect wire ropes.
Tip: When you encounter a protruding wire end, bend it back and forth manually, until it separates from the wire. This will protect neighboring wires from wearing out.
Diameter reduction is a critical factor in steel wire rope wear and if not properly taken care of, it can result in rope breakage. Excessive abrasion, loss of core mass, corrosion or inner wire failure are all factors that contribute to diameter reduction.
To get an accurate measurement of the rope’s diameter, measure the rope at three different points at least 5 feet apart. Take the average of these three measurements to determine the true diameter.
Any measurements showing a reduction of ⅓ or more, indicate that a replacement should follow without delay. A diameter reduction of less than 1/3 still requires attention, and the inspector or the ship’s crew should be on guard in the next scheduled wire rope inspection.
Failure from abrasion or corrosion is a result of deficient deck equipment inspection or insufficient wire rope lubrication respectively. Internal corrosive damage is more difficult to identify than any other types of degradation. In most cases, the damage has progressed more than the external signs suggest.
Wire rope storage plays a significant role in the rope’s operation life.Wire rope corrosion and pitting can be avoided if ropes are safely stored in a clean, cool, dry and well-ventilated place. Steel wire ropes should not by any means rest on the floor, and should be protected from water, dust or any chemical fumes. Long term storage requires periodic greasing, turning the reel upside down for preventing grease dripping and possibly re-winding to another reel with larger inner tube diameter.
Wire ropes should be maintained with periodical lubrication. In order to prevent internal corrosion, a pressure lubricator is suggested to be used. In this case, a small amount of grease is used to lubricate the rope internally, while the deck stays grease-clean. Pressure lubricators clean the rope before they grease it so that the new grease enters a clean rope. The type of grease used is very important for maximum protection and greasing efficiency.
Steel wire ropes exposed to dirt, grime and other contaminants, have to be cleaned with a wire brush and petroleum (unless a pressure lubricator is used). Optimal cleaning of wire ropes can extend their service life and guarantee safe operations.
The reeling process is of high importance for the longevity of wire ropes. To protect them from being damaged, it is important that the surface of the drum is clean, smooth and dry. Improper reeling may cause wire-rope strands to spread or get flattened, when in contact with one another, as successive layers are being spooled and upper layers apply pressure on the lower ones.
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Our proprietary and innovative German-engineered rope designs deliver the highest levels of performance and safety, superior breaking strength values, the highest bending fatigue resistance, superior crushing resistance, and the best rotational resistance characteristics for high lifts.We have decades of global experience and on-site engineering support in the crane, OEM and underground mining sectors.
CASAR has an extensive range of products available and we can customize to your application.Our wire rope specialists will assist customers in design, selection, installation and operation to improve rope performance and maximize service life.
Shortly after the new bridge was commissioned in February Maine Department of Transportation officials noticed the lifts pan"s wire cables were experiencing a condition officials are calling “wavy ropes.” DOT press secretary Ted Talbot said the condition does not affect the operation of the bridge but will expedite the replacement of the cables before their 25-year lifespan is up.
“The contractor, the operating rope manufacturer, the machinery supplier and the engineer of record have all inspected the wire ropes and the lift span"s operating system. This condition does not result in a loss of strength or impact the normal safe operation of the bridge,” Talbot said. “However, due to the ‘wavy rope" condition, it is MDOT"s understanding that normal and expected wear of the ropes will be accelerated. As a result, replacement of the operating ropes will likely need to occur sooner than the expected 25-year life."
Talbot said MDOT will continue to monitor the condition and will order an additional set of operating ropes in the near future to have available for installation at a later date when determined to be necessary.
Wire rope will develop defects during use through several different mechanisms each of which will affect the strength of the rope and therefore limit the working life of the rope.
This is the second article of Part 2 of our Technical Series on Wire Rope Safety. Click here for an outline of the entire Technical Series on Wire Rope.
The number of wire breaks will increase steadily during the life of the rope due to several factors but primarily due to fatigue caused by the rope travelling through sheave wheels. Neither the OHS Act nor the MHSA stipulates how many wires need be broken before a wire rope is discarded. In addition to the number of wires broken, attention must be given to the position and the concentrations of wire breaks as a localized concentration, although less than the number specified, will be sufficient reason to discard.
Inspection is done by first visually inspecting the full length of the rope. In some cases it can be helpful to spool the rope slowly through the hand. Special attention has to be paid and strong protective gloves must be worn. A soft cotton or similar type cloth held against a moving rope will be caught by protruding ends and thus detect the broken wires.
The detection of broken wires in the strand valleys is important but can be difficult. The use of a wire brush on a dirty, heavily lubricated rope can loosen, but not always remove old lubricant and the brush may have to be cleaned frequently with a solvent. Where solvents are used to clean the rope surface, they should be used sparingly and the rope section should be thoroughly lubricated afterwards.
Reduction in diameter can be caused by abrasion, corrosion or a local failure of the rope core. It is recommended that a wire rope should be discarded when the rope diameter anywhere is reduced to 90 % of the nominal diameter.
Corrosion may be external or internal, general or localized. It is recommended that a wire rope should be discarded when the surface of the wires is severely roughened or pitted, or if the wires are slack within the strands due to wastage.
This deformation, while it may not necessarily affect the strength of the rope, can transmit pulsation and produce uneven rope wear. When the rope is laid on a level surface under no load, the maximum height of the “wave” should not be greater than the nominal rope diameter + 1/3, otherwise the rope should be removed from service.
A birdcage develops when the outer layer of strands becomes longer than the inner layer or layers. The condition may occur as a result of incorrect fitting, tight sheaves, shock loading, incorrect use of a swivel or the application of a heavy load to a new rope before the strands have settled into position. Ropes with a birdcage should be discarded.
A local increase in rope diameter with the core easily visible between several covering strands can be caused by shock loading or, in the case of fibre main core ropes, by the absorption of moisture. A node is a justification for discard.
Deformation caused by a loop in a rope being tightened when the rope cannot rotate about its axis to release the torque. The tight bend or kink thus formed can result in a serious loss of strength due to unbalance in the lay lengths. Ropes with kinks must be discarded.
Wire rope is extremely sturdy and can be used in many different applications. In order to withstand harsh conditions, wire rope has basic guidelines of inspection it must meet. Continue reading to find out the guidelines of inspection for wire rope.
Abrasion damage is usually caused by the rope making contact with an abrasive surface. It can also be caused by simply passing over the drum and sheaves during regular, continued use. To minimize this risk, all components should be in proper working condition and be of appropriate diameter for the rope. Badly worn sheaves or drums will cause serious damage to a new rope and will greatly diminish the integrity of the rope quickly.
Corrosion is hard to assess but is more problematic than abrasion. Corrosion is usually the result of the lack of lubrication. It will most likely take place internally before there are any apparent signs on the rope’s surface. One telltale sign of corrosion is a slight discoloration, which is generally the result of rusting. This discoloration indicates a need for lubrication which should be dealt with as soon as possible. Failure to attend to this situation will lead to severe corrosion which will cause premature fatigue failures in the wires and strands. If this occurs, the rope will need to be removed immediately.
Diameter reduction is an extremely serious deterioration factor and can occur for several reasons. The most common reasons for diameter reduction are excessive abrasion of the outside wires, loss of core diameter/support, internal or external corrosion damage, or inner wire failure.
Examining and documenting a new rope’s actual diameter when under normal load conditions is critical. During the life of the rope, the actual diameter of the rope should be regularly measured at the same location under similar loading conditions. If this protocol is followed correctly, it should divulge a routine rope characteristic—after an initial reduction, the overall diameter will stabilize, then gradually decrease in diameter during the course of the rope’s life. This occurrence is completely natural, but if diameter reduction is confined to a single area or happens quickly, the inspector must quickly identify the source of the diameter loss and make the necessary changes if possible. Otherwise, the rope should be replaced as soon as possible.
Crushing or flattening of wire rope strands can happen for many reasons. These issues usually arise on multilayer spooling conditions but can also develop just by using the wrong wire rope for the specific application. Incorrect installation is the most common cause of premature crushing/flattening. Quite often, failure to secure a tight first layer, which is known as the foundation, will cause loose or “gappy” conditions in the wire rope which will result in accelerated deterioration. Failure to appropriately break-in the new rope, or even worse, to have no break-in protocol whatsoever, will also result in poor spooling conditions. The inspector must understand how to correctly inspect the wire rope, in addition to knowing how that rope was initially installed.
Another potential cause for the replacement of the rope is shock loading (also known as bird-caging). Shock loading is caused by the abrupt release of tension on the wire rope and its rebound culminating from being overloaded. The damage that ensues can never be amended and the rope needs to be replaced immediately.
There are several different instances that might result in high stranding. Some of these instances include the inability to correctly seize the rope prior to installation or the inability to maintain seizing during wedge socket installation. Sometimes wavy rope occurs due to kinks or very tight grooving issues. Another possible problem arises from introducing torque or twist into a new rope during poor installation methods. In this situation, the inspector must assess the continued use of the rope or conduct inspections more often.
There are a lot of guidelines for troubleshooting wire rope. At Silver State Wire Rope and Rigging, Inc., we take these guidelines seriously, and so should you. All of our products are tested and guaranteed to be the best fit for your specific needs. We can also help you with your troubleshooting needs. Contact us today!