LEEA Foundation Certificate (Global) Workbook PDF

LEEA – Foundation Certificate (Global) – Course Workbook Textile Slings Textile slings are manufactured from man-made fibres such as: Polyamide (nylon) Polyester Polypropylene Additionally, fibre rope slings may also be produced from natural fibres such as: Manil...

LEEA – Foundation Certificate (Global) – Course Workbook Textile Slings Textile slings are manufactured from man-made fibres such as: Polyamide (nylon) Polyester Polypropylene Additionally, fibre rope slings may also be produced from natural fibres such as: Manila Sisal Hemp Although these will very rarely be found in service nowadays. New, specialist man-made fibres, such as HMPE (High Modulus Polyethylene) are now being produced to manufacture specialised lifting slings. These feature high cut and abrasion resistance; Although the various fibres have many common features, they react differently to temperature, chemical contact and environment. We will consider these matters in the Lifting Accessories Diploma training course. Types of textile slings Textiles slings can be found in various forms: 71 Page © LEEA Academy - FOU (Global) Workbook v 1.6 Jan 2024  LEEA – Foundation Certificate (Global) – Course Workbook Flat woven webbing slings Are also commonly known as belt slings, are used for a variety of lifting purposes. They are a textile sling which is soft and easy to handle whilst offering rigidity across their width. They are ideal for handling loads which require some support when being lifted as the load is spread across the full width of the webbing, avoiding point contact as is the case with chains or ropes. They are therefore less likely to cause damage to the load’s surface than rope, wire rope or chain slings. However, they are less robust and more easily damaged than equivalent capacity wire rope and chain slings. Roundsling Roundslings comprise of a core enclosed in a protective cover. The core is the load-bearing part of the roundsling and is in the form of a hank of yarn made up from one or more strands of the parent fibre material wound together continuously and joined to form an endless sling. The protective cover is a woven tubular outer sleeve of the same parent material as the core, whichis designed to be non-load bearing as it is intended only for protection and containment of thecore. Man-made fibre roundslings are an endless textile sling that is soft and pliable to use, easy to handle and especially useful on delicate surfaces. They are less robust and more liable to damage than equivalent capacity wire rope and chain slings. Fire Rope Slings Fibre rope slings are the traditional form of textile sling whose origins are recorded in the earliest history of lifting equipment. Their use has declined in recent years in favour of the newer forms of textile slings, i.e., flat woven webbing slings and roundslings but they may still be found in general use throughout the industry. Fibre rope slings are produced from cut lengths of rope which are then hand spliced. 72 Page © LEEA Academy - FOU (Global) Workbook v 1.6 Jan 2024  LEEA – Foundation Certificate (Global) – Course Workbook Fibre rope slings are less pliable than other forms of textile sling and are bulky to handle. Unlike flat woven webbing slings and roundslings they present a hard, point contact to the load although this is less severe than with chain or wire rope. Single leg, multi-leg or endless fibre rope slings can be produced. They are made by hand splicing eyes at each end of a piece of rope or by splicing one cut end of a rope to the other end, forming an endless loop. With multi-leg slings, the eye one end of each sling leg is made through a master link. Where this is done, the use of thimbles is advised to protect the eyes. Eyes are produced by bending the rope to form a loop. The strands at the end of the rope are separated and then tucked back into the standing part of the rope against the lay to form the eye, in a similar way as with wire rope. This is done in such a way that they lock and do not slip when a load is applied. There are differences in the splicing requirements, depending on the type of rope used. This is due to differing coefficients of friction. Identification visually, the various fibres appear much the same. This makes identification extremely difficult. An international system of colour-coded labels, which carry the information necessary to be marked on a sling (see marking), has therefore been adopted in standards as follows: 73 Page © LEEA Academy - FOU (Global) Workbook v 1.6 Jan 2024  LEEA – Foundation Certificate (Global) – Course Workbook Shackles Shackles are probably the most common and universal lifting accessory. Their uses are extensive. They may be used to connect a load directly to a lifting appliance, to connect slings to the load and/or lifting appliance, as the suspension for lifting appliances or as the head fittingin certain types of pulley blocks. There are three main types of shackles used for lifting today: 1. Bow 2. Dee 3. Grab types Shackles are normally forged from various grades of steel. Higher quality alloy steels give a higher safe working load than those made in higher tensile steels, while higher tensile steel shackles have a higher safe working load than those made in mild steel. Some manufacturers continue to make shackles to old now withdrawn standards, whereas many have now adopted the current standards. The older, now withdrawn shackle standards fully specified all dimensions of the shackle. In contrast, the current standards tend to specify only some dimensions fully, the rest being specified as a maximum or minimum value. Shackles to the older standards are sized by the diameter of the material in the shackle body and not the diameter of the pin. Shackles to later standards are usually sized by their WLL. Dee Shackle All shackle standards specify dee shackles, with some specifying both a large dee and a small dee shackle. A large dee shackle is a shackle that has ample internal clearances in the body and jaw, and which is appropriate for general engineering purposes. A small dee shackle is a shackle that has moderate internal clearances in the body and jaw but, size for size has a SWL higher than that of the large dee. It is suitable for use with hook eyes, eyebolts, egg links, wire rope thimbles, etc. and for the head fittings of ships’ blocks. Bow Shackle Similarly, all shackle standards specify bow shackles, with some specifying both a large bow and a small bow shackle. A large bow shackle is a shackle which has ample internal clearances in the body and jaw, and which is appropriate for general engineering purposes. A small bow shackle is a shackle which has moderate internal clearances in the body and jaw but, size for size, has a SWL higher than that of the large bow. It is suitable for use with the eyes and bodies of hooks, eyebolts, egg links, wire rope thimbles, etc. and for the head fittings of ships’ blocks. Grab Shackle A grab shackle is a dee shackle having a screwed countersunk pin, designed for use with grabs where the shackle must pass through a circular aperture of minimum diameter. 74 Page © LEEA Academy - FOU (Global) Workbook v 1.6 Jan 2024  LEEA – Foundation Certificate (Global) – Course Workbook Application The selection of the shape of the shackle body will depend on the intended use. It is desirable to use a shackle with as small a jaw opening as is consistent with an adequate articulation of the connection. Dee shackles are, in general, used to join two pieces of lifting equipment. Bow shackles are, in general, used where more than one attachment is to be made to the body or to allow freedom of movement in the plane of the bow. Pins There are two types of shackle pin in common use, the screw pin, and the bolt, nut and cotter pin (commonly referred to as the safety pin or 4-piece shackle). Screwed pins with eye and collar are the most common type of pin and are suitable for a wide range of uses. However, if they are subject to movement and vibration (e.g. by a sling moving over the pin), they can loosen and unscrew. The bolt with hexagon head, hexagon nut and split cotter pin is used where a positive connection is required as it cannot unscrew unintentionally. They are also ideal where a permanent connection is required, (e.g. connecting the top slings to a spreader beam). Notes: 75 Page © LEEA Academy - FOU (Global) Workbook v 1.6 Jan 2024  LEEA – Foundation Certificate (Global) – Course Workbook Eyebolts We will consider the main three types of eyebolt: 1. Eyebolt with link 2. Collared 3. Dynamo Eyebolt with Link This eyebolt has advantages over the other patterns of eyebolt when the loading needs to be applied at an angle to the axis and/or the plane of the eyes. Provided that the angle of the load to the axis of the screw thread does not exceed 15° they may be loaded in any direction to the full SWL rating. Thread sizes range from 20mm to 48mm in the metric coarse pitch series or ¾” to 1¾” in the imperial BSW or UNC threads. They have a small, squat, eye that is blended into the collar in all directions and a link is fitted to allow articulation and connection with other lifting components. The link is designed to accept a hook of the same capacity. Compared to size for size with Collar Eyebolts, the SWL for axial load is lower. In all other arrangements, the SWLs are relatively greater than those of Collar Eyebolts when used in the same conditions. Unlike the Collar Eyebolt, the load can be applied away from the plane of the eye, as the link will articulate to align and the collar has equal strength in all directions, making correct fitting easier. 76 Page © LEEA Academy - FOU (Global) Workbook v 1.6 Jan 2024  LEEA – Foundation Certificate (Global) – Step Notes NOTES FROM THE VIDEO: Collared Eyebolt Designed for both axial and angular loading. The eye is blended to the collar in one plane. However, the eye is not large enough for direct connection to a hook and it is necessary to use a shackle for connection to other components. They are generally available in a range of capacities of 0.4t to 25t SWL with corresponding thread sizes of 12mm to 72mm in the metric coarse pitch series, and capacities of 0.25t to 30t with corresponding thread sizes of 3/8” to 3” BSW or UNC. The SWL range of the imperial threaded collar eyebolt differs from that of the metric threaded collar eyebolt because they are intended as replacements for eyebolts to older now withdrawn standards. When used in pairs of the same capacity, the plane of the eye of each eyebolt must not be inclined to the plane containing the axis of the two eyebolts by more than 5°. In order not to overstress the shank, this alignment may be achieved by use of shims up to a maximum of half of one thread in thickness. A reduction in the maximum load that may be lifted is necessary due to the angular loading. This is far more drastic than is required with the Eyebolt with Link. Although in axial loading, size for size, Collar Eyebolts have a higher SWL, their capacity when subject to angular loads is far lower. 77 Page © LEEA Academy - FOU (Global) Workbook v 1.6 Jan 2024  LEEA – Foundation Certificate (Global) – Step Notes NOTES FROM THE VIDEO: Dynamo Eyebolt The Dynamo Eyebolt is the most basic in design and the most limited in use because it only suitable for axial (directly vertical) lifting only. Essentially it is a ring sitting on top of the shank and has only a small collar. Although it is limited to axial loads, the eye is large enough to accept a hook of the same capacity. Dynamo Eyebolts get their name from their historical use by electric motor manufacturers, who would fit them to the tapped hole over the balanced lifting point of the motor. They are generally available in capacities of 0.32t to 10t with corresponding thread sizes of 12mm to 52mm in the metric coarse pitch series. Imperial threaded dynamo eyebolts are also available in a range of capacities of 0.25t to 10t with corresponding thread sizes of 3/8” to 2” BSW or UNC. 78 Page © LEEA Academy - FOU (Global) Workbook v 1.6 Jan 2024  LEEA – Foundation Certificate (Global) – Workbook Rigging Screw These have a tubular body, internally threaded at each end, with one right hand and one left- hand thread connecting to terminal fittings of various forms, e.g., screwed eyes, hooks or forks. They are also known in some industries as bottle screws Turnbuckle This has an open body consisting of reins, with internally threaded bosses at each end, with one right and one left-hand thread connecting to terminal fittings of various forms, e.g., screwed eyes, hooks or forks. A drilled inspection hole across each end of the body of a rigging screw facilitates checking that the threaded portion of the terminal fitting has adequately engaged with the body. 79 Page © LEEA Academy – FOU (Global) Workbook v1.6 Jan 2024  LEEA – Foundation Certificate (Global) – Workbook Notes: 80 Page © LEEA Academy – FOU (Global) Workbook v1.6 Jan 2024