Tables 1-2 and 1-3 list the approximate safe work- ing loads of new fiber lines with a safety factor of 5.
NOTE: These are for reference only. Check the manufacturer's ratings before determining the safe working loads, as they may differ from the tables.
You may not always have a chart available to tell you the safe working load for a particular size of line. There is a rule of thumb that will adequately serve your needs on such an occasion. The formulas below are examples of synthetic fiber lines used for rigging, not slings.
For nylon or polyester line, change the line diameter into eighths of an inch, square the numerator, and multiply by 60.
Example: 1/2-inch nylon line = 4/8-inch diameter
SWL = 4 x 4 x 60 = 960 lb
For polypropylene line, multiply the diameter by 40, and for polyethylene, by 35.
Remember that the strength of a line decreases with age, use, and exposure to excessive heat, boiling water, or sharp bends. Especially with used line, you should give these and other factors affecting strength careful consideration and make proper adjustment in the breaking strength and SWL of the line.
During the course of a career, CEs often need to hoist or move heavy objects. Wire rope is used for heavy-duty work. In the following paragraphs, we will discuss the characteristics, construction, and usage of many types of wire rope as well as the safe working load, use of attachments and fittings, and procedures for the care and handling of wire rope.
Table 1-2. - Safe Working Load of Fiber Line
APPROXIMATE SAFE WORKING LOADS OF NEW FIBER LINES - POUNDS
Safety Factor = 5
|Nominal Line Diameter (inches)||Manila||Nylon||Polypropylene||Polyester||Polyethylene|