Size is determined by linear density; diameter is given as a nominal value, that is, it may vary slightly. If a specific diameter value is specified, linear density and minimum breaking strength values may be different from those given in the tables. Size number is given as reference.

The working load of a rope shall be determined by dividing the minimum breaking strength by the design factor. Design factors range from 5 to 12 for non-critical applications. Because of the wide range of rope usage & conditions, exposure to several factors affecting rope behavior, and the degree of risk to life and property involved, it is not realistic to make standard recommendations as to design factors on working loads. However, to provide guidelines, a range of design factors and working loads are provided for rope in good condition with appropriate splices, in non critical applications and under normal service conditions. Normal service is generally considered to be used under static or very modest dynamic load conditions.

Design factors at low end of the suggested range should only be selected with expert knowledge of conditions and professional estimate of risk, based on the critical conditions of use listed below.

Design factors at the higher end of the range shall be used when:

1. Small ropes ( because they can be more severely damaged by cutting, abrasion and sunlight.)
2. Loads are not accurately used.
3. Operators are poorly trained.
4. Operation / procedures are not well defined and / or controlled.
5. Inspection is infrequent.
6. Abrasion, cutting, dirt are present.
7. Shock loads or extreme dynamic loadings.
8. High temperatures are present.
9. Chemicals are present.
10. Ropes are kept on service indefinitely.
11. Tensions on ropes are maintained continuously for long periods.
12. Rope can be subject to sharp bends or is used over pulleys or surfaces with too small radius.
13. Knots are used, (strength is reduced by upto 50%. )

For critical applications a design factor greater than 12 may be necessary. Users must determine the design factors, as they are the only ones, who can assess service conditions and establish operating procedures. The load applied shall not exceed the working load. If uncertain, contact a qualified engineering consultant for assistance.

Whenever a load is picked up, stopped, moved or swung, there is an increased force due to dynamic loading. The more rapidly or suddenly such actions occur, the greater the force will be. In extreme cases, the load put on the ropes may be two, three or even more times the normal load involved; for instance when picking up a tow on a lack line or using a rope to stop a falling object. Therefore in all such applications as towing lines, lifelines, safety lines, climbing ropes etc. design factors must reflect the added risk involved.

Users must also be aware that dynamic effects are greater on a low elongation rope such as Manila than on a high elongation rope such as Nylon and greater on a shorter rope than a longer one. The range of design factors given contains provision for very modest dynamic loads. This means that the load must be handled slowly and smoothly to reduce to minimize dynamic effects.

A dangerous situation occurs if personnel are in line with a rope under excessive tension. Should the rope fail, it may recoil with considerable force- especially if the rope is nylon. The results may be life threatening in rare cases Persons must be warned against standing in line with the ropes.

The design factor ranges are not necessarily intended to apply in those applications where a thorough engineering analysis of all conditions of use has been made by qualified professionals. In such cases, breaking strength, elongation, energy absorption, behavior under long term to cyclic loading, and other pertinent properties and operating procedures may be evaluated to allow the selection of a design factor best suited to the requirements.