SLING
PROCEDURES Covering the world. Protecting the Earth.
SOLMAX.COM
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SLING PROCEDURES As part of Solmax’s customer service policies and procedures, Solmax supplies with each shipped roll, two (2) Eye & Eye web slings (Figure 1) to facilitate the unloading of the rolls and their onsite manipulations. The slings supplied by Solmax are made of Polyester and have a 5:1 safety factor. Usually, Solmax supplies the “Flat Untapered” (Figure 2) type but for convenience and availability reasons, Solmax might supply some “Flat Tapered” slings (Figure 3). EYE & EYE:
Figure 1 - Eye & Eye Web Sling
Figure 2 - Flat Untapered Slings
Figure 3 - Flat Tapered Slings
Although Solmax supplies these slings to its customers, it is Solmax’s recommendation and the customer’s responsibility that any worker that uses these slings, follow an appropriate training on how to use and manipulate this handling equipment, in order to prevent any incident from occurring. As a compliment to the proper training, you will find in this document some valuable technical information, as well as unloading guidelines for the slings that will facilitate their use and help prevent incidents.
SLING TECHNICAL INFORMATION The slings supplied with each Solmax PE rolls are made of 100% polyester. They have a Working Load Limit (W.L.L.) of 3,100 lbs and a 5:1 safety factor, which means that the strength needed to break the slings, should be around 15,500 lbs. Each sling measures 10 ft. in length and is tested as per the ASME B30.9-2006 Safety Standard for Cableways, Cranes, Derricks, Hoists, Hooks, Jacks, and Slings. This information can be found in a table, such as Table 1, located on a tag on each sling. MATERIAL
100% POLYESTER
S/F
5:1
W.L.L.
3100 LBS
E/L
10 ft
STANDARD M/D
ASME B30.9-2006
Table 1- Sling Properties Tag
MONTH
YEAR
Figure 4 - PE Rolls with slings attached
Solmax’s PE rolls weigh approximately 4,000 lbs each. As such, two (2) slings should always be used to lift the rolls. As illustrated in Figure 4, Solmax always supplies two (2) slings per roll. Do not exceed capacities of the slings working load.
The slings supplied are mainly for unloading purposes. However, if the slings have not been damaged, they can be reused for further handling of the rolls. Prior to using any sling, new or used, the following information should always be verified. Table 2- Sling Inspection Procedures
INSPECTION
TYPE
WHAT TO LOOK FOR
Initial
Verify if the correct sling is being used
Frequent
Periodic
• • • • • • • • • • •
Acid or Caustic burns (Figure 5) Melting or charring Holes, tears, cuts (Figure 6), snags Broken/worn stitching in load-bearing splices Excessive abrasive wear (Figure 7) Knots (Figure 8) Excessive pitting or corrosion, or cracked, distorted or broken fittings Weld Splatters (Figure 9) Frays and Pulls (Figure 10) Other visible damage Missing / illegible markings
Same as “Frequent” inspection
HOW OFTEN Prior to the first use as new or as repaired
Daily
Based on how often the sling is used and the severity of service conditions, but at least annually
SLING ACID BURN
SLING KNOT
Figure 5- Sling Acid Burn
Figure 8 - Sling Knot
SLING WELD SPLATTERS
SLING CUTS
Figure 6 - Sling Cuts
SLING ABRASION
Figure 9- Weld Splatters
SLING FRAYS AND PULLS
Figure 7- Sling Abrasion Wear
Should any of the damages described in Table 2 or seen in Figures 5 to 10 be identified on the sling, that sling should not be used as its W.L.L. will be compromised. As damage to the slings may occur during the unloading process, Solmax supplies a few extra slings to its customers with each shipment.
SLING HANDLING INFORMATION Although the W.L.L. of the slings is 3,100 lbs, many factors will affect the effectiveness of the sling. As such, please find the following information.
Handling Method
As seen in Table 3, there are different ways to lift Solmax’s rolls using the supplied slings.
CHOKER HITCH Sling passes through one end around the load, while the other end is places on the hook. Load control is limited with only one sling rigged in a choker hitch. A choker hitch will never provide full 360 degree contact. For full contact use a Double Wrap Choke Hitch. The Choke Point should always be on the sling body, not on the sling eye, fitting base of the eye or fitting, splice or tag.
Table 3 - Sling Handling Methods
VERTICAL HITCH
BASKET HITCH
One end is on the hook, while the other end attached directly to the load. Use a tagline to prevent load rotation.
The sling cradles the load while both eyes are attached overhead. As with the choker hitch, more than one sling may be necessary to help ensure load control.
The slings supplied by Solmax are attached to each roll using the “Choker Hitch”. However, it is the sling user’s responsibility to use the appropriate handling method for their use. As such, Table 4 explains the effects of the handling method on the W.L.L.
Handling Method Choker Hitch
Vertical Hitch Basket Hitch
Table 4 – Handling method and W.L.L.
W.L.L. 2,480 lbs 3,100 lbs 6,200 lbs
As Solmax supplies two (2) slings per roll and each roll weighs approximately 4,000 lbs, depending on other conditions that will be described in future sections, the choker hitch method should be considered a proper handling method of the rolls. However, it is the user’s responsibility to ensure that this handling method is the proper one, based on all the lifting variables.
Sling-to-load limit
The horizontal angle formed between the sling leg and the “top” of the load is called the sling-to-load angle (Figure 11). Ideally, this angle should be at a 90° angle or in other words, vertical.
Sling-to-load angle
Figure 11- Sling-to-load angle
As Table 5 shows, the loss factor for the W.L.L. decreases as the sling-to-load angle decreases. Table 5- Loss Factor Chart
LOSS FACTOR CHART
Sling-to-load Angle (°)
Loss Factor
Sling-to-load Angle (°)
Loss Factor
90
1.000
55
.8192
85
.9962
70
.9397
80
75
65
60
.9848
.9659
.9063
.8660
50
45
40
35
30
25
.7660
.7071
.6428
.5736
.5000
.4226
To evaluate if the sling-to-load angle used is appropriate to lift the rolls, Formula (1) should be used. đ?‘Š.đ??ż.đ??ż.đ?‘“=đ??żđ??š đ?‘Ľ đ?‘Š.đ??ż.đ??ż.đ?‘–
(1)
Example: If 2 slings supplied by Solmax, that have no visible damages identified on the rolls, are used as Choker Hitches to lift a 4,000 lbs roll at 70° Sling-to-load angle, the following calculation should be performed. đ?‘Š.đ??ż.đ??ż.đ?‘“= .9397 đ?‘Ľ 2,480 đ?‘Ľ 2=4,661 đ?‘™đ?‘?đ?‘
Therefore, if used as choker hitches and at a 70° sling-to-load angle, the slings supplied by Solmax will have a W.L.L. greater than 4,000 lbs and be the proper handling method to lift Solmax’s PE rolls.
Based on Table 5, the minimum sling-to-load angle, when using the choker hitch handling method, to carry a 4,000 Solmax PE roll with two (2) slings is 55°. Therefore, Solmax does not recommend using the supplied slings with a sling-to-load angle smaller than 55° when using the choker hitch method. Should a different handling method be used or if other variables, such as the ones described in future sections affect the effectiveness of the sling, the minimum sling-to-load angle may vary.
Choker angle When using the choker hitch handling method, the location of the choke on the roll will have an effect on the effectiveness of the W.L.L. Figure 12 shows different choker angles that can occur during handling of the rolls.
Rated Capacity %
Over 120
100
60-89
74
30-59 0-29
87
de
g
18 0
90
de g
eg 0d 12
90-120
135 deg
Angle of Choke Degree
60 deg
62
30 deg
49 Figure 12 - Choker Angle
LOAD
When transporting a load, the choker angle should always be greater than 120°. When the choker angle is below 120°, the rated capacity is reduced as per the Figure 12. As an example, if two (2) slings with a sling-to-load angle of 80° and a choker angle of 70°, the W.L.L. would be calculated as follows: đ?‘Š.đ??ż.đ??ż.đ?‘“=đ??żđ??š đ?‘Ľ đ?‘…đ??ś đ?‘Ľ đ?‘Š.đ??ż.đ??ż.đ?‘–
(2)
đ?‘Š.đ??ż.đ??ż.đ?‘“= .9397 đ?‘Ľ 0.74 đ?‘Ľ 2,480 đ?‘Ľ 2=3,449 đ?‘™đ?‘?đ?‘
Therefore, the slings used in this example would be at risk of breaking and should not be used in this configuration. For this reason, Solmax recommends to always use choker angles greater than 120° to avoid any failures.
Handling Equipment The same way the sling-to-load angle will affect the effectiveness of the W.L.L., the angle within the eye of the sling will reduce it as well. Figure 13 shows different types of handling equipment and their effect on the angle within the eye.
Figure 13 - Handling equipment effects on angle within the eye
Solmax has not collected any data on the exact loss factor of using one handling method over another. However, a greater eye angle will decrease the effectiveness of the W.L.L. more than a smaller angle. Therefore, the sling user should make every effort to reduce this angle. As such, Solmax does not recommend the use of forklifts during unloading given their effect on the angle within the eye.
Also very important to consider when choosing handling equipment is if the selected equipment can cut the sling. The most common cause for a sling to be taken out of service is for showing signs of cutting. Therefore, the handling equipment should be free of sharp edges that can damage the sling and reduce its effectiveness. For the reasons mentioned above, Solmax recommends the use of hooks (Figure 14) when handling rolls with slings.
Figure 14 - Recommended hook for sling handling
Transportation terrain While the dead load of an average Solmax geomembrane roll is approximately 4,000 lbs, its dynamic load can be substantially increased when driving on an uneven bumpy road. The up and down movement of the roll when driving on a bumpy road, will put stress on the slings that may break them. Construction jobsites temporary roadways are usually made of uneven bumpy roads. Taking this reality into consideration, when using slings to transport geomembranes rolls on a jobsite, every effort should be made to reduce the up and down movement of the rolls, such as driving at a slower pace and trying to avoid large bumps and holes.
User training Solmax recommends that any user of the supplied slings follows a proper training for handling loads using slings. These trainings are usually offered by the local Health and Safety agencies under course titles such as “Hoisting” and/or “Rigging”. Please contact your local Health and Safety agency for more details.
CONCLUSION & RECOMMENDATION Solmax supplies with each roll of geomembrane slings that can assist our customers in handling the purchased rolls. Each supplied sling has a tag describing its physical properties and its testing certification. Although these slings are considered appropriate handling equipment for the rolls, the handling methods will greatly affect the performance of these slings. It is the user’s responsibility to verify prior to each use that the sling is appropriate for the task at hand, to use the proper handling equipment and methods, and to obtain the proper training. Solmax cannot be held responsible for any damage or incidents that occur due to improper handling of the supplied slings. For more information on the supplied slings for handling of geomembranes rolls by Solmax, please contact your Solmax representative.
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