In a multi-part wire rope system where the blocks have a tendency to twist -- or for a single-part hoist line that doesn't require the degree of rotation-resistant properties found in a 19 x 7 rope -- the 8 x 25 Resistwist rope has found successful application. The rotation-resistant characteristic is achieved by laying the eight outer strands around an independent wire rope core so these strands are in the opposite direction to the lay of the core. Thus, when the rope is in tension, opposing rotational forces are created between the core and the outer strands.

Though not as rotation-resistant, the 8 x 25 Resistwist is more stable than a 19 x 7 rope. It also has increased resistance to bending fatigue and crushing. This is achieved through the use of eight-strand construction with an independent wire rope core.

Like any application where an installation's rope type is changed, the 8 x 25 Resistwist rope should be substituted only after carefully comparing specifications and strength requirements.

• More crush resistance than a standard 19x 7 rope while providing the same rotation resistance.
• Higher strength-to-diameter due to compacted wires in the strands. With increased metallic area, it provides rope strengths equal to 6 strand XXIP IWRC ropes of the same diameter.
• Resistance to bending fatigue due to the uniformity of the wires within each strand. The strand's outer surface is smooth, reducing contact pressures between the rope's strands and radial pressures as it operates over sheaves and drums.
• Exceptional stability due to the higher density strands coupled with the smooth outer surface.
• Improved handling, operating and spooling characteristics.
• Reduced wear to sheaves and drums.

Flex-X 19 delivers extra value when you need high strength in a rotation-resistant wire rope. Its rotation-resistant construction provides a smooth, extremely compact wire rope with more steel in the cross-section than conventional ropes.

Flex-X / Power Flex has also demonstrated greater fatigue resistance to substantially cut rope expense and extend rope service life. It's ideal for single-part or multi-part hoist lines wherever you encounter spooling problems, drum crushing, block twisting or have fast line speeds.

Rotation-resistant ropes can frequently provide the best and most economical service in specific applications when you choose, handle and use them properly.

Contra-helically laid, rotation-resistant ropes are different from standard ropes because they're designed to reduce rope torque. Modes of failure and wear for rotation-resistant ropes can differ from those for standard rope constructions. The very nature of these ropes requires special handling, selection and usage not encountered with standard constructions. They are susceptible to kinking, crushing and unbalancing in the form of "core pops" and "birdcages". Use extreme care to avoid operational practices that can possibly lead to these conditions.

Rotation-resistant ropes should not be used with swivels that allow rope rotation -- or in single part lifts where the load can rotate. Rotation will cause a reduction in strength, unequal loading in the rope and possible rope unbalance. If any significant change in diameter is found in a short length of a rotation-resistant rope, the rope needs to be replaced.

These ropes should be replaced when you see two randomly distributed crown wire breaks in six rope diameters -- or four randomly distributed crown wire breaks in 30 rope diameters.

Because rotation-resistant ropes are special, there are separate design, maintenance, inspection and removal criteria established for them by applicable industry regulations and standards.

We recommend that rotation-resistant ropes be used with a minimum design factor of 5.0.

* These strengths apply only when a test is conducted with both ends fixed. When in use, the strengths of these ropes may be significantly reduced if one end is free to rotate