Synthetic Slings Inspection Criteria
Effects of Wear and Abuse
Far too many web slings have been discarded prematurely simply because abusive and careless work habits caused irreparable damage. Following are examples of damage typically caused by abuse and misuse.
Extending Sling Service Life
Provision for storing synthetic slings are an effective way to improve the life of a sling. Storing slings away from dirt, abrasives, or contaminants serves to maintain the optimum lifting capacity.
Sling Inspection and Repair
Effects of Wear and Abuse
Far too many web slings have been discarded prematurely simply because abusive and careless work habits caused irreparable damage. Following are examples of damage typically caused by abuse and misuse. Regardless of whether a sling shows damage from abuse or normal wear, the overriding rule is in all cases is that sling eyes should be cut and the sling discarded immediately whenever damage is detected.
TENSILE BREAK – Characterized by a frayed appearance at the point of failure or damage. Such damage is caused by loading the sling beyond its existing strength. The example pictures was pulled to destruction on a testing machine.
CUTS – A cut is easily identified by a clean break in the webbing structure or fibers, and usually results from the sling contacting a sharp object or unprotected edge of a body or eyes of a web sling. Red Guard warning yarns are woven into webbing of many slings to provide a warning when a serious cut has occurred. Cuts from contact with sharp corners during lifts can often be avoided by using wear pads on the sling for protection of the fabric.
CUT AND TENSILE DAMAGE – The sample shown illustrates a typical shop failure in which a sling is used after having received a cut by a sharp object along one edge of the sling body. The cut severely reduces lifting capacity, and continued usage will result in the sling breaking much as shown. Such a failure often occurs at a level far below the Rated Capacity of the sling.
ABRASION DAMAGE – The most common abrasion damage occurs either when a sling slips while in contact with a load during a lift, or when being pulled from under a load. Abrasion is characterized by frayed fibers on the surface which exposes the “picks,” or cross fibers, of the webbing that hold in place the load-bearing (lengthwise) fibers. Further abrasion at this point will expose the Red Guard warning yarns to signal the inspector or sling user that serious damage – and loss of lifting capacity – has occurred. Any damage to load-bearing fibers should be viewed seriously.
ACID DAMAGE – Although polyester webbing has considerable resistance to certain acids, any contact with strong acids should be avoided. Nylon should never be exposed to any acid. Metal fittings on slings should not be exposed to any acid or corrosive liquid.
Example A – The damage show to this nylon webbing occurred when sulfuric acid (such as used in an automobile batter) was heated to 100 degrees C (212 F) and dropped on the webbing. The charring of surface fibers seen here is typical of acid damage. The deterioration shown will coninue over time and severely affect webbing strength.
Example B – A piece of Nylon webbing was immersed in sulfuric acid at room temperature for three weeks, resulting in the significant damage shown. Note that fibers are softened and swollen, and the entire fabric is grossly distorted, virtually destroying the webbing. Precautions should be taken to never store slings where they may be exposed to acide fumes (which can be as destructive as liquid) or to possible contact with liquid.
Extending Sling Service
- Provision for storing synthetic slings are an effective way to improve the life of a sling. Storing slings away from dirt, abrasives, or contaminants serves to maintain the optimum lifting capacity.
- Cleaning slings to remove dirt, grime, abrasives (such as sand or caliche) will help to prolong service life. These contaminants wear the fibers and reduce their strength.
- Slings should be cleaned with a mile soap. Capacity tags must be legible. After rinsing the sling, it should be hung to air dry.
NOTE: Prolonged exposure to direct sunlight detrimentally affects synthetic fibers, reducing capacities over time.
Sling Inspection & Repair
Inspection Critera
Cited below are removal criteria established by the Occupational Safety and Health Administration and the American National Standard Institute Safety Standard.
Repairs
Repairing synthetic slings should never be performed in the field. Any sling to be repaired should first be inspected by a qualified individual to determine if rework is possible.
Repair work should be performed by a manufacturer.
Once repair work is finished, the sling must be tested to TWICE the rated working load.
Records of repair work should be maintained through the life of the sling.
OSHA 1910.184 – Criteria for Removal From Service.
Synthetic web slings shall be immediately removed from service if any of the following conditions are present:
- acid or caustic burns
- melting or charring of any part of the sling surface
- snags, punctures, tears, or cuts
- broken or worn stitches
- distortion or fittings
ANSI B30.9-9.5.6.2 – Possible Defects. A sling shall be removed from service if any defects such as the following are visiable:
- acid or caustic burns
- melting or charring of any part of the sling surface
- snags, punctures, tears or custs
- broken or worn stitches
- wear or elongation exceeding the amount recommended by manufacturer
- distortion of fittings
- other apparent defects which cause doubt as to the strength of the sling should be referred to the manufacturer for determination.
While most of the foregoing standards are quite specific regarding some removal criteria, a certain amount of judgement is involved in others. The issue of wear to the sling body, the salvage of webbing, and to sling eyes creates the greatest amount of contentions. We recommend that any exposure of the RED GUARD wanring years is sufficient cause to remove a sling from service and destroy it.