Published on 02-Dec-2021

Basics about Wire Rope Testing

Basics about Wire Rope Testing

In today’s times, wires, ropes and cables are considered very important in the building and construction industry. They are also used for pulling, lifting and holding various things. Although the wires are strong enough to get their work done, they need to go through some safety procedure called wire rope testing.  

Wire rope testing is a form of electromagnetic inspection using equipment designed specifically for steel braided wire rope. Steel rope is used in a variety of applications such as amusement parks, mine shafts, suspension bridges and overhead cranes.

The equipment utilizes two strong magnets in a clam shell type set up to clamp around the rope. These magnets create a constant magnetic field in the steel rope. Since the magnetic field is constant, the amount of flux necessary to saturate the rope is a function of the cross-sectional area of the rope.

If the section of the rope that passes through the machine contains defects such as broken wires, corrosion thinning or stretching, the magnetic flux will be affected. These changes are interpreted on an oscilloscope display.

With proper calibration and training the technician can determine the percentage of cross-sectional loss, broken wires, and overall loss of break strength.


Wire rope flaw detection:
Wire rope flaw detection is a proven technology that can deliver up to 4m/s and accurate quantitative results. When used correctly, it can determine the life and condition of a wire rope that can withstand corrosion, abrasion, and fatigue.

The technology is designed for inspection of the round, flat and steel-rubber flat wire ropes in a wide range of applications such as mining, cranes and heavy lifting onshore and offshore, cableways, cable bridges, elevators, guy ropes of flare stacks and masts, overhead transmission lines.

How do you inspect wire ropes:
Firstly, use the rag-and-tag visual method for inspecting any external damages. Grab the rope lightly and with a rag or cotton cloth, move the rag slowly along the wire. Broken wires will often "porcupine" (stick out) and these broken wires will snag on the rag. If the cloth catches, stop and visually assess the rope. It is also important to visually inspect the wire (without a rag). Some wire breaks will not porcupine. 

Measure the diameter of the rope. Compare these diameter measurements with the original diameter of the rope. If the measurements are different, this change indicates external and/or internal damage to the rope.

Visually check for abrasions, corrosion, pitting, and lubrication inside the rope. You can try inserting a marlin spike beneath two strands and rotate it to lift strands and open the rope.

What to do if the wire rope is damaged:
The wire gets damaged for multiple reasons. In this article we will try to cover all bases. 

→ Replace rope if there are:

  1. 6 or more broken wires in one lay

  2. 3 or more broken wires in one strand, in one lay

  3. 3 or more broken wires in one lay in standing ropes 


→ Replace the rope, if outer wires are:

  1. Become flat from friction

  2. Become shiny from wear

  3. Wear exceeds 1/3 of their diameter


→ Replace rope if wear on individual wires exceeds 1/3 of their diameter.

→ Replace 6-strand rope if the stretch reduces the diameter by more than 1/3rd.

→ Replace the rope if any wires or strands are cut or burned. Damaged ends can be removed and seized, otherwise rope must be replaced.

→ Look for strands opening up in cage-like clusters. If present, the rope must be replaced.

When to inspect wire rope:

Safety is paramount when it comes to wire rope testing. Hence it is advisable to inspect wire ropes at regular intervals. Here are some of the times when you should inspect your wire ropes:

  • When you are installing a wire rope for the first time.
  • Inspect the wire rope every alternate day for damages
  • Keep records of daily inspections.

Causes for wire rope to get damaged:

A wire rope can get damaged due to a variety of reasons. Some of them are listed below:

  1. Fatigue from repeated bending even under normal operating conditions.

  2. Overloading the safe working load limit.

  3. Mechanical abuse - crushing, cutting or dragging of rope.

  4. Being used when frozen - if work is performed at lower than 15.5°C, the use of the sling should follow the manufacturer's recommendations.

  5. Corrosion from lack of lubrication and exposure to heat or moisture (e.g., wire rope shows signs of pitting). A fibre core rope will dry out and break at temperatures above 120°C (250°F).


Conclusion:

We hope that this article will be helpful for everyone who is interested in NDT. Are you looking for a single platform that has all the information related to Non- destructive Testing? Your search ends here. One Stop NDT has everything related to Non-Destructive Testing in one place.

Backed by professionals with unprecedented experience & presence of more than 20 years in NDT Market, One Stop NDT gives you a chance to freely communicate and interact with experts. 




Tree PNG back

Companies

Tree PNG back

Articles

Forums

Forums

Webinars

Webinars

Tree PNG back

Jobs

Application Notes

News