By Grant Laidlaw
Experiencing problems of a technical nature, drop us a line at firstname.lastname@example.org with problem page in the subject line.
Welcome to the PROBLEM PAGE. We find many people request assistance in the practical aspects of the industry. In response we will investigate the problem and endeavour to present the best possible solution. Thank you for all your questions sent in. Send your problems (and sometimes your creative solutions) to email@example.com with problem page in the subject line. You may include pictures. Attie Fourie sent the following: We, at our company put in some big air-conditioning equipment. Sometimes we are asked to do some rigging. I see you are giving lots of advice so can you give me some basic guidelines for rigging as I feel that this can be dangerous.
Larger units of equipment such as cooling towers, rooftop package units and chillers can vary greatly in size and mass and would require a specialist rigging team. The items that you would consider when you are planning to move an object are: 1. 2. 3. 4.
The mass and shape of the object. Whether the object is fragile. How high the object must be lifted. How far the object must be moved.
For the placement of new equipment drawings showing the final position and dimensions of the unit together with the rigging and installation instructions are required.
Attie, thank you for your question. In the air conditioning and refrigeration industry there is a vast diversity of equipment and technicians need to understand that all items will require some form of handling and lifting to be positioned correctly and in accordance with the design layout. The shapes, dimensions and mass can vary greatly. Each item of equipment will need careful attention with regard to its size, shape and mass before planning how they will be handled, rigged, lifted, and moved. The precautions to be taken before any moving, handling and lifting takes place must be considered as part of the planning.
Rigging and handling instructions usually kept in the packaging case or attached to the equipment unit.
The consequences if the rigging and installation instructions are not followed are that the equipment could be damaged and a warranty claim might be
rejected causing unnecessary cost and loss to the company Room air conditioning units, for example, may be transported on a dolly or hand trolley to the designated position and then manhandled into the final position.
This equipment is usually of large mass and size, and high value such as chillers, compressor units, cooling towers, condensers and roof top package units. In most cases planning and organisation would normally be the duty of the contracts manager and to be delegated to a crane hire company and where necessary to specialist riggers. I will not go into more detail in this area as this is not normally the responsibility of an air conditioning / refrigeration technician. METHODS OF RIGGING
A crated component or piece of equipment that is not too heavy could be carried by hand by one or two persons without causing an injury or damage, but when the size, shape and mass get too big lifting equipment has to be considered.
The first method of moving and lifting a small item of equipment is by carrying. A person carrying a load needs to be aware of the shape and size of the object. When an item is being carried and it is not possible to see the ground in front, care must be exercised on rough or slippery surfaces.
At the place of storage there usually are facilities for lifting the item onto the transport vehicle, for example: a forklift truck, an overhead gantry or levelling device. The more important planning is required on site. The sort of important information could be included in the rigging instructions? • • • • •
Instruction to inspect unit for damage. Instruction to have all panels in place prior to rigging. Instruction to use spreader bars. Instructions on placing the unit. Instructions on service space requirements.
Permission to move an item of equipment onto site is sometimes required from the building contractor’s site manager or agent. Refer to the construction drawings showing the plant layout and position of the unit on site together with the base fixing arrangement Factors that need to be considered when examining a site? Where would the delivery vehicle be parked? Can a crane be positioned to reach the unit position? If the unit has to be moved by means of a trolley, is the ground suitable for moving a loaded trolley? Is the base (plinth) for the unit ready and correctly built? In addition what safety precautions must be in place to meet the risk assessment? It is important to note that safety information must be documented and given in writing. It is in addition important to identify the final position for the equipment before examining the route and method of rigging. There are items of the plant and pieces of equipment that because of their size, shape and mass must be handled and rigged into position using a crane or other methods of rigging.
The simplest method of moving an item of equipment that is not too heavy or too large to carry is to make use of a hand truck or trolley or to use a dolly. These aids would be used mostly for room air conditioning units still packed in their boxes or small fans such as axial flow and propeller fans and small refrigeration condensing units. Hand truck or trolleys are sometimes provided with securing straps to prevent the load from being dislodged or falling while being moved.
Dollies are used to carry bulky loads and components which can be packed in such a way that moving from place to another is relatively easy. To lift a unit from ground level to the upper floor of a building a builderâ€™s hoist could be used with the permission of the contractor. The mass and size of the unit would have to be considered to decide on the suitability of the hoist for the equipment being moved. A block and tackle (Chain block) is often used to lift items of equipment to a position that is elevated on a building or as a means of moving the item on pipe rollers across a flat surface. To be able to lift an item of equipment the block and tackle must be suitably rated for the mass (Safe Working Load, SWL) and the attachment point above where the lift is to take place is secure. The mechanical advantage will have to be such that one or two persons can provide the necessary power to lift the load and hold it in position. The load must be secured in a sling arrangement that is suited to the size and shape of the load.
Attie, I have covered the planning stages and some of the basic methods of rigging in this issue. In the next issue I will go into more detail with regards to the practical use of chains, slings, hooks, wire ropes, SWL, tags and trifors to name a few as well as additional methods used. REFERENCES: Special thanks to: References ACRA SANS 10296 Occupation health and safety for construction Occupation health and safety act and regulations 85 of 1993 3rd Addition OHS Act MerSETA TG/FG Thanks to all for writing in with interesting questions. I try to answer questions that are of common interest to people in industry. Looking forward to hearing from you â€“ Grant Laidlaw
BLOCK AND TACKLE
Coffing blocks are similar to chain blocks but used when space is limited.
Published on Dec 5, 2007
We, at our company put in some big air-conditioning equipment. Sometimes we are asked to do some rigging. I see you are giving lots of advic...