4. INSTALACIÓN Y CONTROLES PRELIMINARES
5.2 Panel de control desde el suelo y unidad de control eléctrica
When using slings observe the following:
1. Protect them from wear, abrasion, impact loading, crushing and kinking or similar abuse.
2. Always use a sling with a greater WLL than the anticipated weight of the load if: a. The exact load weight is unknown.
b. There is a possibility of shock or dynamic loading. c. There will be an increase in load, through wind effect.
d. When the load has to be lifted over vulnerable plant (because there is no alternative route).
3. Do not assess the required WLL of a multi-leg sling by dividing the load weight by the number of sling legs. There is no way of knowing that all sling legs will carry equal amounts of the load. With multi-leg slings, it is possible that two legs could be carrying the majority of the load whilst the other sling legs just balance the load. If it is obvious that the load is unbalanced, the leg tension (not the weight of the load) in the sling legs carrying the majority of the load must be assessed when determining the sling SWL required. If in doubt do not sling the load but seek advice from a supervisor.
NOTE: FOR MULTI-LEG SLINGS THE WLL IS QUOTED FOR AN ANGLE OF THE
LEG TO THE VERTICAL, AT THE MASTER LINK, OF 0°°°° TO 45°°°°.
4. Be aware that tension in sling legs varies with the angle of the leg to the vertical at the hook. A 'sling angle' is usually denoted by the angle of the leg to the vertical at the lifting point, which is:
a. With two- leg slings, the angle of the leg to the vertical.
b. With three-legged slings, the angle between one leg and the vertical (0° to 45°). c. With four-legged slings, the angle between one leg and the vertical (0° to 45°). 5. Never use a sling that is knotted or kinked.
6. Prepare the load landing area. Most loads can be lowered on to timber battens allowing the slings to be withdrawn. Never land a load on to the load slings
7. Keep slings away from welding or cutting operations.
8. A multi-leg sling must not be used if, when fitted to the load, the angle from the vertical at the master link is greater than 45°; sling with longer legs must be selected.
9. Take care not to 'kink' wire rope or a sling. A kink in a sling or rope will distort the sling/rope, severely affecting its strength (WLL) causing it to be removed from service and destroyed. Kinks are usually formed in one of two ways:
a. Bad slinging practices, e.g. tensioning a sling over an acute angle, or round too small a diameter.
b. By pulling on a loop accidentally formed in a sling. If the sling is pulled instead of 'untwisted', a kink will quickly form in the sling (see Fig 5).
Fig 5 How a Kink is Pulled into a Wire Rope 10. Do not wrap a wire rope around a hook (see Fig 6).
11. Always avoid bending a sling around small diameters. The minimum radius around which a sling shall be bent is 6 times the diameter of the rope.
12. Do not join two slings together by, 'threading the eye' (see Fig 7). If two slings are to be joined together, they must be joined with a shackle of at least the same SWL as the slings to be joined.
Fig 7 Joining Slings
13. Never shorten a sling by tying a knot in it. A knot will cause severe kinking of the sling when the load is lifted, an immediate reduction in the SWL of the sling, and result in the sling being removed from service and destroyed.
14. Semi-permanent terminations of wire ropes are frequently made using wire rope clips. These provide a quick and easy way to terminate wire ropes and when properly applied including the insertion of a thimble in the eye of the sling, and the application of sufficient torque to the securing nuts, provide up to 80% of the strength of the original rope. Wire rope slings that are made using this method shall not be used for lifting. U-Bolt rope grips must not be used. The only acceptable rope grip is the double-saddled type (fist grip)
Refer to Appendix 11 for installation instructions
Figure 8 Application of Rope Grip's
15. When using a sling in a choke-hitch mode, do not force the eye of the sling into closer contact with the load. This dangerous malpractice and is often called "battening down". The choke-hitch must be allowed to form its own 'natural angle’, which will be about 120° (see Fig 9). If forced down, the angle between the sling 'legs' will probably increase beyond 120° and become dangerous.
16. The slinging of pipes and tubulars is a very common lifting operation. Attention is drawn to EP2005-0264-G01(section 2.1 page 13)
Fig 9 Do Not Batten Down Slings
The slings must be double wrapped with a choke hitch taking care not to cross over the wires on the underside of the pipe or tube bundle (Fig 9). The choke hitch shall be pulled tight to contain the bundle and secured using an wire clamp (Asbro clamp) or a fist grip, If using a fist grip, a tie wrap must then be fitted to prevent the reeved eye slipping over the fist grip, in case the bundle loosens in transit. Refer to BSP Lifting Information Memo LIM-001-05 for further details.
a. The sling positioning must be approximately 25% (of the total length) in from either end of the tubular (Fig 9).
b. Each sling shall have a WLL at least equal to the gross weight of the load.
c. Ensure that the correct length of slings are used. The recommended safe lifting angle of the sling leg is 30 degrees from the vertical; the maximum lifting angle must never exceed 45 degrees from the vertical.
Do not bend a sling round sharp corners of a load. Use wooden packing to protect the sling from sharp edges and to generally increase the radius around which the sling must bend. The wrapping of a fire blanket, or similar, around a beam is cosmetic and unacceptable.
17. Multi-leg slings must not be used if there is a possibility that they will damage the equipment to be lifted. Alternative lifting arrangements must be made.
18. When lifting a load, if there is the slightest doubt as to the stability of the load, it must be slowly lifted clear of the ground, if the load then tilts, it must be lowered immediately and re-slung in a more stable position.
19. Tag lines must be attached to the load and not to the lifting gear.
15.9.6.1
Wire Clamp (ASBRO) Pre-Use Inspection
Wire clamps must be visually inspected before they are used as follows: a. Check the clamp is of the correct size for the wire rope.
b. Inspect the saddle for excessive wear, cracks, deformity and impact damage. c. Inspect the claw for excessive wear, cracks, deformity and impact damage.
d. Inspect the wedge for excessive wear, cracks, deformity and impact damage and check that the wedge lock is free to move
15.9.6.1
Rejection
The clamp shall be rejected when there is any obvious excessive wear, cracks, deformity or impact damage or if the clamp allows the rope to slip through when landing the bundle thus allowing the bundle to become slack.
15.9.6.2
Care and maintenance
The clamps must be inspected for damage after removing from sling. The Wedgelock shall be greased, if required, and the clamp reassembled and stored in a box marked with the correct size/diameter for future use. The wire clamp must be stored in a dry atmosphere.