TYPICAL ROPE DAMAGE
Mechanical damage due to rope movement over sharp edge projection while under load.
Localised wear due to abrasion on supporting structure. Vibration of rope between drum and jib head sheave.
Narrow path of wear resulting in fatigue fractures, caused by working in a grossly oversize groove, or over small support rollers.
Two parallel paths of broken wires indicative of bending through an undersize groove in the sheave.
GETTING STARTED
WIRE ROPE INSPECTION The single most important operational check to be made on hoisting and rigging equipment is the rope and rigging inspection. Assurance of safety and economy in use of the equipment dictates the requirement for a program of periodic inspections of all load supporting wire rope and fittings. Factors such as abrasion, wear, fatigue, corrosion, improper reeving and kinking are often of greater significance in determining the usable life of wire rope than are strength factors based on new rope conditions.
HOW OFTEN TO INSPECT
INSPECTION All wire rope in continuous service should be observed during normal operation and visually inspected on a weekly basis. A complete and thorough inspection of all ropes in use must be made at least once a month and all rope which has been idle for a period of a month or more should be given a thorough inspection before it is put back into service (check local government regulations). All inspections should be the responsibility of and be performed by an appointed competent person who makes a complete report of the rope condition.
CRITICAL INSPECTION POINTS
There are certain points along any given rope which should receive more attention than others, since some areas will usually be subjected to greater internal stresses, or to greater external forces and hazards. Carefully select the most critical points for close inspection, points where failure would be most likely to occur. The same critical points on each installation should be compared at each succeeding inspection. Critical points which should be considered for careful inspection on most installations include the following:
MEASURING ROPE DIAMETER
Every periodic inspection must include diameter measurement at critical points and recording of measurements for future comparisons. Most inspection standards are specific on permissable reductions in diameter. The criteria for the installation and industry involved should be known by the inspector before starting to take measurements. Measurements are proper only when made across the crowns of rope strands, so that the true diameter is the widest diameter at any given point on the rope. Always rotate the caliper on the rope, or the rope inside the caliper, to take a measurement.
MEASURING ROPE LAY
One rope lay is the length along the rope which a single strand requires to make one complete spiral, or turn, around the core. It is an engineering factor in the design of a rope, and is carefully controlled during manufacture. Since there is often some adjustment in rope lay during the initial break-in stages of a ropes usage, it is recommended that rope lay measurements should be made after the initial loading, for comparison purposes at succeeding periodic inspections. One method for measuring rope lay is with ordinary blank white paper and a pencil. Firmly hold the paper on the rope and stroke the rope with the side of the pencil, using a small angle iron as a guide, so the ropes print appears on the paper.
FINDING BROKEN WIRES
INTERNAL ROPE EXAMINATION
Any time interior damage, broken wires or core failure is suspected, a section of rope should be opened for internal examination. This may be accomplished without destroying the rope's future usefulness if due care is exercised and wires are not kinked or notched.
INSPECTING SHEAVES
A proper fitting sheave groove should support the rope over 135-150 degrees of rope circumference. Observe the groove so that it may be clearly seen whether the contour of the gauge matches the contour of the bottom of the groove.
Sheave inspection should also include the condition of bearings and shaft. With the rope relaxed, the sheave should be rotated by hand to determine the fit of the bearing and effectiveness of its lubrication, whether the sheave runs true without wobbling on its shaft, whether the bottom of the groove is still concentric or round in relation to the shaft and whether the sheave and its shaft are in proper alignment with other sheaves or components of the system.
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EVALUATING DRUMS
Even though both these gauges properly follow groove contours, when used side-by-side they indicate grooves are too close and that the "Drum Pitch" is less than the rope diameter. Two gauges which overlap in this manner reveal that wraps of rope will scrub when spooling on to or off the drum.
Inspection criteria for drums will usually specify the following: - Minimum number of dead wraps to remain on the drum. - Condition of drum grooves, if a grooved drum, and the surface of a smooth drum. Condition of flanges at the ends of the drum.
END ATTACHMENTS
All end attachments have one characteristic in common: they restrict, to some degree, the free movement of wires at the end of the rope. This impairment of the ability of wires to adjust and move at the end can ultimately result in breakage of wires at the point where restriction occurs. As a result, broken wires are a primary concern when inspecting end attachments on a rope. A single broken wire is usually reason to question continued use of the rope and more than one is usually sufficient cause for rejection. Broken wires may be more difficult to locate at end fittings than in other sections of rope. An awl used to pick and probe at the point where
INSPECTION REPORTS
click on the above report graphic to enlarge (suitable for landscape printing)
This report was prepared to serve as a guide for making thorough periodic examinations of wire ropes, sheaves and drums and serve as a permanent record of the inspection. One form should be used for each specific machine at each inspection. Before beginning an examination of an installation, fill in the blank spaces at the top of the report. These identify the company, equipment
(i.e. Worn right hand flange, damaged rope port). OVERALL CONDITION -
Overall condition rates the rope sheaves or drum (i.e. Poor).
COMMENTS -
This column allows the inspector to write specific notes, recommendations or out right rejection of the inspected item (i.e. Rope rejected due to damage at the drum, re-machine drum).
When an inspection is complete or has proceeded far enough for the inspector to reject the rope and or associated sheaves and drums the inspector should complete the form and sign the document. This document should then be kept on file for future reference. Refer to local or federal regulations to confirm the proper procedure for tracking and maintaining reports. Please note that this inspection report is also available on Micro Soft Excel. Please contact your Wire Rope Industries representative for a copy or contact our technical personnel on the Internet (www.wirerope.com). Back toTop
