SYNTHETIC ROUNDSLINGS CI May 2014

Transcription

1 Cordage Institute All rights reserved. No part of this standard/guideline may be reproduced or utilized in any way or by any means (electronic or mechanical) without permission in writing from the Cordage Institute. Approved for use. Cordage Institute International Standard SYNTHETIC ROUNDSLINGS CI May Introduction 1.1. Purpose: This standard specifies the requirements related to safety, including methods of identification, rating, inspecting, and testing roundslings made from synthetic fibers. The roundslings covered by this standard are intended for general purpose and critical horizontal and vertical load movements. These load movements may include vehicle recovery, load manipulation and/ or load securement. 2. Training: Synthetic roundsling users shall be trained in the selection, inspection, cautions to personnel, effects of the environment, and rigging practices as covered by this standard. 3. Terminology: 3.1. Terms Specific to this document. Breaking strength: The total force or tension at which the sling fails. Designated person: See qualified person. Design factor: A ratio of the minimum breaking strength to rated capacity. Rated load tables are based on a 5-1 design factor. Nuclear, offshore, or engineered lifts may require different design factors. Dynamic loading: A dynamic load is the force that moves or changes when acting on a structure. Fitting: A load bearing component that is fitted to the sling. It can be of steel, aluminum, or other material that is compatible with the rated load limit of the roundsling. High tenacity fiber: Synthetic fiber with strength equal to or greater than 15.0 grams per denier. Cordage Institute, 994 Old Eagle School Rd., Ste 1019, Wayne, PA Tel: Fax: info@cordageinstitute.com Web:

2 Multi-path roundsling: A roundsling constructed with more than one load bearing core per sling. Proof load test: A non-destructive load test, usually to twice the rated load of the sling. Qualified person: A person who, by possession of a recognized degree or certificate of professional standing in an applicable field, or who, by extensive knowledge, training, and experience, has successfully demonstrated the ability to solve or resolve problems relating to the subject matter and work. Rated load sometimes referred to as Rated Capacity: The load or capacity that must not be exceeded. Tables of rated loads are included in this document for various roundslings. Roundsling: An endless sling composed of a continuous load bearing core made from synthetic yarns, enclosed in a protective synthetic cover, used for general lifting purposes. A roundsling may be of a single-path or multi-path construction. Standard Tenacity Fiber: Synthetic fiber with a strength less than 15.0 grams per denier. Shock loading: Any condition of rapid lifting, sudden shifting of load or arrest of falling load which imparts higher than normal forces on the sling. The dynamic effects often can be well in excess of the static load that is being lifted and may exceed the rated load. Single -path roundsling: A roundsling constructed with one load bearing core per sling. Synthetic fiber: Man-made material used for the cover, the core and the thread of the roundsling product. 4. Materials for roundsling 4.1. Core: The synthetic yarns shall be wound endlessly on a multiple of turns for even distribution of the load Core Material: There are two categories of synthetic core material covered by this standard: high tenacity with 15 grams per denier or higher and standard tenacity with less than 15 grams per denier. LCP, HMPE, PBO, Para-aramid, or any combination are examples of high tenacity synthetic fiber. Polyester fiber is an example of standard tenacity fiber. (For details see: CI , Fibers for Cable, Cordage, Rope and Twine) 4.3. Cover: The cover material is to protect the load bearing core yarn from harmful effects presented by normal conditions of use. These conditions include chemical exposure, heat, abrasion, cutting, sunlight, and other significant environmental factors. These factors can be addressed by additional protection including abrasion pads, special materials, additional layers or covers, or engineered cut protection Thread and stitching: The stitching that is used to secure the cover, tag, and to separate load bearing paths in multi-part slings should be polyester, nylon, Para- Aramid, LCP, HMPE, or other synthetic thread Finishes: The characteristics of a roundsling can be enhanced by the addition of chemical coatings and finishes. The material used must be compatible with the composition of the core, cover, and thread used to manufacture the roundsling product. Performance of the roundsling should be improved and must not be impaired by the addition of finishes. 2

3 5. Hitches: Common roundsling hitches are shown in figure 1. FIGURE 1 Hitch/Vertical: A method of attachment whereby the sling extends from the lifting point to the load in a straight connection. Hitch/Choker: The sling is passed around the load and back through itself and is connected to the lifting point. The sling then tightens around the load when force is applied. Choker hitches are rated at 80% of the vertical hitch. Hitch/Basket: The sling is passed from the lifting point around the load and back to a lifting point. Hitch/Multi -Leg: 5.1. Angles and rated load calculations: The following equation shall be applicable to determine rated loads for multi- leg hitches with roundslings, for multiple leg roundslings, and for basket hitches where the legs are not vertical. Rated load = single leg vertical hitch rated capacity multiplied by the number of legs multiplied by the sine of the minimum horizontal angle. 3

4 Horizontal Angle Sine of Angle 60 deg deg deg Proof Load Testing: Proof load testing shall be performed when requested by the purchaser or may be done by the manufacturer as a part of their quality system The roundslings shall be pulled on a tensile testing machine that has been calibrated to ASTM E- 4 or similar specifications within twelve months of the date of the test. Proof testing on all roundslings by the manufacturer may be included as part of their quality system The force applied during this test should be twice the Rated Load. If fittings are part of the sling assembly, the fittings must be included in the proof load test. Any distortion of the fittings or roundsling shall be considered a failure of the proof load test For proof load testing, the pins shall be of a size that will withstand the force applied without distortion Repaired roundslings shall be proof tested before they are returned to service. If fittings are part of the roundsling, they shall also pass a proof load test. 7. Break Testing: Break testing shall be performed using a tensile test machine that has been calibrated to ASTM E- 4 or similar specifications within twelve months of the date of the testing. For break testing, the pin sizes shall be of a size that will withstand the force applied without distortion. The roundslings shall be tested in a manner that allows the load bearing core fibers to spread out and share the load evenly. THE DIAMETER OF THE TEST PINS SHALL BE DOCUMENTED ON THE BREAK TEST CERTIFICATE. Slings shall be tested in a single vertical hitch and shall be pulled until the maximum peak load is reached. Pin diameter and span of the jaw may affect the break test results For break testing of slings made with high tenacity core material (see Para. 4.2) the pin sizes shall be of a size that will withstand the force applied without distortion. The pin sizes should conform to the sizes given in table For break testing of roundslings with standard tenacity core material (see Para. 4.2) the pin sizes shall be of a size that will withstand the force applied without distortion. The pin sizes should conform to the sizes given in table The roundsling must withstand a minimum of five times its rated load (for a design factor of 5), or other load as specified by the design factor, before failure Prior to pulling a roundsling to failure, it should be first proof tested, but only if this is a normal part of the manufacturer s quality system. 8. Roundsling identification: Each sling shall be tagged with a permanent legible tag with the following information: 1. The name or trademark of the manufacturer 4

5 2. The manufacturer s code or stock number 3. The rated load for various types of hitches, and the angle on which the hitch is based 4. The type of the core fiber material or trademark. 5. The type of the cover fiber material or trademark. 6. A warning that provides a basic understanding to the user of sling hazards 7. Number of legs, if more than one. *NOTE: See the manufacturers warnings for operable temperature ranges 8.1. Identification Responsibility: The roundsling manufacturer is responsible for the identification when the sling is made The user is responsible for tag legibility and tag maintenance while the sling is in the user s possession If the tag becomes illegible, or is missing, the roundsling shall be removed from service and destroyed, or returned to the original manufacturer, or authorized agent, for repair evaluation and retagging. 9. Environmental Considerations: Roundslings used in chemically active environments may be adversely affected. Consult the manufacturer before subjecting a roundsling to environmental hazards When not in use, synthetic roundslings should be stored in a clean, dry place. Heat sources and sunlight should be avoided Chemically active environments can affect the strength of synthetic lifting slings. Different chemicals will react with different exposure to bulked nylon, polyester, aramids, and olefins. Chemically active environments may affect the core, cover, and stitching differently. Please see the manufacturer for recommendations Temperature: Refer to the tag for Operating Temperature Ranges Polyester roundslings shall not be used in contact with objects or at temperatures in excess of 194 F (90 C) or at temperatures below -40 F (-40 C) Some synthetic yarns do not retain their published breaking strength above 140 F (60 C). The roundsling manufacturer should be consulted for the temperature range of roundslings made from other synthetic yarns. 10. Fittings: Fittings shall be able to withstand a proof test to twice the rated load without material deformation Fittings shall be compatible with the mechanical and environmental requirements imposed on the roundsling Fittings must be smooth and have sufficient openings to attach the roundsling without crushing, bunching, or unduly restricting the roundsling Previously used or welded fittings shall be proof tested before being returned to service. 5

6 10.4. The diameter and width of the load bearing surface of a fitting will affect the strength of the roundsling, resulting in a possible reduction of the design factor. The roundsling manufacturer s recommendations must be followed when fittings are used with roundslings. 11. Inspection: A three stage procedure is recommended to help ensure that slings are inspected with appropriate frequency Initial inspection: Prior to use, all new or repaired roundslings shall be inspected by a qualified person to verify compliance with this standard Frequent Inspection: In normal service conditions, a visual inspection for damage must be performed by the user or other designated person each day or shift before the sling is used. In severe service conditions, a visual inspection for damage must be performed by the user or other designated person before each use. Written records are not required for frequent inspection. Manufacturer recommendations must be followed if a higher rate of inspection frequency, such as before each use, is prescribed Periodic inspection: a regular, dated, documented inspection by a qualified person. This periodic inspection is made according to experience with prior service life of roundslings in the same or nearly identical usage, and must be performed at least annually. The inspection report must be kept on file. A. Periodic Inspection Frequency: Periodic inspection intervals must not exceed one year. The frequency of periodic inspections should be based on: 1. Frequency of sling use 2. Severity of service conditions 3. Nature of lifts being made 4. Experience gained on the service life of slings used in similar circumstances. B. Time Interval Guideline: The guidelines for time intervals are as follows: 1. Normal service yearly 2. Severe service monthly to quarterly 3. Special service as recommended by a qualified person C. Documentation: 1. The most recent documentation of a periodic inspection that was performed shall be maintained. 2. Inspection records of individual slings are not required. 12. Inspection and Removal Criteria: Remove a roundsling from service if any of the following damage is indicated during inspection. The roundsling should be destroyed, or returned to the manufacturer for repair evaluation Missing identification or identification that is unreadable Slings should be inspected for evidence of cutting or tearing of the outer cover. Slings with cuts should be removed from service and sent back to the manufacturer for repair evaluation. Damage to the cover may indicate core damage Inspect slings for evidence of heat damage. Reference the tag, and or contact the roundsling manufacturer for specific operating temperature ranges. 6

7 12.4. Slings using aluminum fittings should not be used where fumes, vapors, sprays, or mists of alkalis or acids are present Slings should be examined throughout their length for abrasion, cuts, heat damage, fitting distortion or damage, or tag illegibility. If any doubts are held by the inspector, the sling should be removed from service Roundslings that suffer damage to the load bearing cores must be removed from service, as they are not repairable Slings removed from service that are not capable of repair should be destroyed and rendered completely unfit for future use Abrasion, heat damage, or cuts to the cover may indicate a loss of strength to the load bearing core, and these slings should not be used until evaluated by the manufacturer Please consider that some roundsling manufactures commonly use fabrication methods which include constructional knots. A constructional knot is formed when the beginning and end of the load bearing core yarns are tied together. 13. Repairs Temporary repairs of roundslings shall not be permitted unless authorized by the manufacturer There shall be no repairs of load bearing core yarns or fittings Repairs to protective covers shall be done only by a qualified person authorized by or performed by the manufacturer Repaired roundslings, INCLUDING ATTACHED HARDWARE OR FITTINGS, shall be proof tested to twice their rated load, and a certificate of proof test shall be issued with the repaired roundsling The repair agent shall have their company name or trademark stamped on the identification tag of the repaired roundsling. 14. Operating Practices Determine the load that will be applied to the sling. The load, including the static and any dynamic loading, shall be within the rated load of the roundsling Select a sling having suitable characteristics for the type of load, hitch and environment Slings shall not be loaded in excess of the rated load. Consideration shall be given to the angle of lift, which will affect the lifting capacity. Diameters of pins and edges also will affect the capacity of the roundsling Slings used in a choker shall not be forced to tighten around the load by pounding with hammers or other objects. Choker hitches are the least effective way to use a sling based on capacity. Two chokers should be used to balance the load. One choker in the center of the load may create an unbalanced situation which could lead to an accident. Use double wrap choker hitches for better load control. 7

8 14.5. Slings used in a basket hitch must have the load balanced to prevent slippage and accidents. Use a double wrap basket hitch for better load control Slings used with fittings shall be compatible with the fittings used. The lifting capacity shall be rated at the lower of the fitting or sling. Fitting openings shall be of the proper shape and size to assure that the sling will seat properly Slings shall be protected from damage. All protrusions, edges and abrasive surfaces shall be kept from contacting sling. Protection shall be placed between the sling and the edge, protrusion, or abrasive surface. A shackle pin may cause synthetic roundslings to cut, and placing roundslings on the unprotected pin of the shackle should be avoided Roundslings shall not be dragged on the floor or drawn across other surfaces that may damage the sling Slings should not be twisted and shall not be tied in knots to shorten their length Slings shall not be pulled from under loads resting on the sling Do not drop objects on roundslings or run over them with vehicles Roundslings which are damaged shall not be used Roundsling hitches must provide control of the load Portions of the human body shall be kept from between the sling and the load and from between the sling and any attachment to lifting devices such as hooks Personnel shall stand clear of suspended loads Personnel shall not ride on the roundsling or suspended loads Avoid snatch or shock loading Twisting and kinking the legs of the roundsling should be avoided Loads applied to the hook should be centered in the bowl of the hooks. Do not point load the hook During lifting with or without the load all personnel shall be alert for possible snagging The roundslings should contain or support the load from the sides above the center of gravity so the load will not tilt when the load is lifted Roundslings shall be of the proper length to provide an acceptable angle of lift Only legibly marked or labeled slings shall be used. If the tag is not legible, or is missing, the sling shall not be used Keep labels or tags away from the load, the hook and the choke hitch point Synthetic roundslings shall be inspected each time before each lift. 8

9 The use of rope and cordage products has inherent safety risks which are subject to highly variable conditions and which may change over time. Compliance with standards and guidelines of the Cordage Institute does not guarantee safe use under all circumstances, and the Institute disclaims any responsibility for accidents which may occur. If the user has any questions or uncertainties about the proper use of rope or cordage or about safe practices, consult a professional engineer or other qualified individual. 9

10 RECOMMENDED PIN SIZES FOR THE DESTRUCTIVE TESTING OF STANDARD TENACITY ROUNDSLINGS SLING RATED CAPACITY (POUNDS) TABLE 1 MAXIMUM PIN DIAMETER FOR DESTRUCTIVE TESTING 5, , , , , * Pin sizes for proof loading slings may be larger than destructive pin sizes * The pin sizes referenced in table 1 and table 2 are designated for use in testing slings in a vertical hitch and may not be adequate for testing round slings in a basket configuration. * For slings with capacity values that fall in between those listed above, the diameter of the test pins shall be determined by using the values of the higher capacity sling. * Higher capacity slings should be tested on pin diameters that will fully and safely support the test load. For additional information, see Associated Wire Rope Fabricators (AWRF) Test Bed Safety Guide. 10

11 RECOMMENDED PIN SIZES FOR THE DESTRUCTIVE TESTING OF HIGH TENACITY ROUNDSLINGS TABLE 2 High tenacity core yarn SLING RATED CAPACITY (POUNDS) MAXIMUM PIN DIAMETER FOR DESTRUCTIVE TESTING 10, , , , , , , , , , , , , , ,000 9 * Pin sizes for proof loading slings may be larger than destructive pin sizes * The pin sizes referenced in table 1 and table 2 are designated for use in testing slings in a vertical hitch and may not be adequate for testing round slings in a basket configuration. * For slings with capacity values that fall in between those listed above, the diameter of the test pins shall be determined by using the values of the higher capacity sling. * Higher capacity slings should be tested on pin diameters that will fully and safely support the test load. For additional information, see Associated Wire Rope Fabricators (AWRF) Test Bed Safety Guide. 11

12 STANDARD PERFORMANCE ROUNDSLINGS (Core made from standard tenacity fiber) TABLE 3 Rated Load (Lbs.) at Design Factor (DF) 5:1 Vertical Choker Basket Hitches 2,600 2,100 5,200 4,500 3,700 5,300 4,200 10,600 9,200 7,500 8,400 6,700 16,800 14,500 11,900 10,600 8,500 21,200 18,400 15,000 13,200 10,600 26,400 22,900 18,700 16,800 13,400 33,600 29,100 23,800 21,200 17,000 42,400 26,700 30,000 25,000 20,000 50,000 43,300 35,400 31,000 24,800 62,000 53,700 43,800 40,000 32,000 80,000 69,300 56,600 53,000 42, ,000 91,800 74,900 66,000 52, , ,300 93,300 90,000 72, , , ,300 Manufacturers are free to set their own distinct rated loads which may be different from the ones included in this standard as Table 3 and Table 4. DO NOT EXCEED RATED CAPACTIY 12

13 HIGH PERFORMANCE ROUNDSLINGS (Core made from High Tenacity Fiber) TABLE 4 Rated Load (Lbs.) at Design Factor (DF) 5:1 Vertical Choker Basket Hitches 10,000 8,000 20,000 17,320 14,140 15,000 12,000 30,000 25,980 21,210 20,000 16,000 40,000 34,640 28,280 25,000 20,000 50,000 43,300 35,350 30,000 24,000 60,000 51,960 42,420 40,000 32,000 80,000 69,280 56,560 50,000 40, ,000 86,600 70,700 60,000 48, , ,920 84,840 70,000 56, , ,240 98,980 85,000 68, , , , ,000 80, , , , ,000 *100, , , , ,000 *120, , , , ,000 *140, , , , ,000 *160, , , , ,000 *200, , , , ,000 *220, , , , ,000 *240, , , , ,000 *320, , , , ,000 *400,000 1,000, , ,000 Manufacturers are free to set their own distinct rated loads which may be different from the ones included in this standard as Table 3 and Table 4. *When using a roundsling in a choke hitch at 100,000 pounds and above, it is suggested that the end user ask the roundsling manufacturer for rigging recommendations. *DO NOT EXCEED RATED CAPACITY: Minimum Ultimate Load for sling capacities higher than this chart may be less than a 5-1 design factor (consult manufacturer) 13