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How to Inspect a Twin-Path Synthetic Roundsling to ASME Standards

One of the most basic but crucial aspects of using a Twin-Path® synthetic roundsling is inspecting it prior to each use.

We often get questions from our customers about what to look for when inspecting a Twin-Path® synthetic roundsling. Customers also want to know if there are any differences in the inspection process for a single-path roundsling and a Twin-Path® roundsling. The inspection processes are the same, but this article will also address additional inspection best practices outlined by Slingmax®, the manufacturer of Twin-Path® synthetic roundslings.

One of the most basic but crucial aspects of using a Twin-Path® synthetic roundsling is properly inspecting it prior to each use. Taking the time to perform a brief visual inspection will confirm that the Twin-Path® roundsling meets the specific job and lifting requirements and will also help to ensure the safety of the user, help extend the life of the equipment, and help to reduce unnecessary equipment repair costs and costly down time. Before each use, the Twin-Path® sling needs to be inspected in accordance with ASME B30.9 Standards, which will be reviewed in detail below.


Throughout the life of a Twin-Path® synthetic roundsling, it will be put through three major inspections:

Initial Inspection (Prior to Initial Use) – Upon receiving the initial shipment from the manufacturer, the Twin-Path® roundsling will be double-checked to make sure that it is the correct product and that it meets the project specifications and lifting requirements.

Frequent Inspection (Each Day or Prior to Use) – Prior to each shift, or prior to a change in lifting application (i.e. switching from one material to another), the user or other designated personnel will check for the following two things:

  • Locate the sling tag and confirm it is intact and legible. Ensure that all of the sling tag specifications meet the current job’s lifting requirements. Don’t use the wrong sling for the wrong weight.
  • Inspect the Twin-Path® synthetic roundsling itself for any damage, irregularities, or signs of wear-and-tear.

Periodic Inspection – These inspections are performed by either a professional service provider, or by a trained or qualified person. Frequency of use, severity of service conditions, and experience gained on service life of Twin-Path® synthetic roundslings used in similar applications are determining factors in scheduling the frequency of periodic inspection, with at least one inspection performed at a minimum of every 12 months and monthly to quarterly in more severe service conditions. Best practice is to inspect and document each sling during your periodic inspection.


Inspecting a Twin-Path Roundsling

Inspecting a Twin-Path Roundsling

A key factor when inspecting Twin-Path® synthetic roundslings is being able to identify a potential issue and taking action on it before the sling is connected to any rigging hardware. A small cut, burn, tear or hole in a synthetic roundsling can compromise the strength and lifting capabilities of the sling when under load, and therefore the sling must be removed from service immediately. If there is any doubt as to the condition of the synthetic roundsling prior to use, it needs to be removed from service and replaced.

The following ASME B30.9 synthetic roundsling inspection standards require immediate removal from service for any synthetic roundsling with any of the following visible occurrences:

  • Missing or illegible sling identification.
  • Acid or caustic burns.
  • Evidence of heat damage.
  • Holes, tears, cuts, abrasive wear or snags that expose the core yarns.
  • Broken or damaged core yarns.
  • Weld splatter that exposes core yarns.
  • Discoloration and brittle or stiff areas on any part of the slings, which may mean chemical or other damage.

**If there are any signs of damage to the synthetic roundsling including any evidence of the following, immediately remove the sling from service:

  • Missing or illegible sling identification
  • Heat damage
  • Knots
  • Fittings that are pitted, corroded, cracked, bent, twisted, gouged, or broken
  • Other conditions, including visible damage, that cause doubt as to the continued use of the sling

If you have any questions or concerns regarding the use, repair, or replacement of your synthetic roundsling, contact the manufacturer for their recommendations.**

inspection frequencies


As seen above, the inspection process for a Twin-Path® synthetic roundsling includes the same criteria outlined by the ASME B30.9 synthetic roundsling inspection standards. Slingmax®, the manufacturer of Twin-Path® synthetic roundslings, has provided best practices for inspection in regards to their Check-Fast® External Warning Indicator (EWI) and Tell-Tail Indicators, as well as additional usage and inspection criteria, which can also be found at

Tell-Tail Indicators on a Twin-Path Roundsling

Tell-Tail Indicators on a Twin-Path Roundsling

  1. Check-Fast® External Warning Indicator (EWI) and Tell-Tail indicators shall extend past the tag area of each sling. If your sling is equipped with Check-Fast® and the EWI is not visible or both Tell-Tails are not visible, remove the sling from service—this could be an indication that the sling was overloaded or possibly shock-loaded. Send the sling in to the manufacturer for repair evaluation.
  2. If Fiber-Optic inspection is installed in the sling, inspect by allowing light to enter the fiber optics. If the fiber optics do not transmit light from end to end, remove the sling from service and contact the manufacturer for repair evaluation.
  3. Slings shall be inspected for evidence of cutting or tearing of the outer cover. Slings with cuts shall be removed from service and sent back to the manufacturer for repair evaluation. Damage to the cover may indicate core damage.
  4. Inspect slings for evidence of heat damage. Sparkeater® slings shall not be exposed to temperatures over 300°F and polyester slings shall not be exposed to temperatures above 194° F / 90° C. Cold temperature exposure down to -40°C / -40°F does not affect the strength of the product.
  5. If any part of the sling shows evidence of chemical degradation or damage, remove the sling from service. Return the sling to the manufacturer for repair evaluation.
  6. Slings using aluminum fittings shall not be used where fumes, vapors, sprays or mists of alkali or acids are present.
  7. Twin-Path® lifting slings and any fittings attached shall be the subject of frequent and regular inspections. In addition to the initial inspection by a competent person and frequent written inspections, the slings shall be visually inspected before each use.
  8. Written inspections shall be performed as required and documents of such inspection by a competent person shall be kept on file in the safety department of the plant or site where used. Inspections may be done more often based on frequency of use, severity of conditions, and experience of past service life.
  9. Slings shall be examined throughout their length for abrasion, cuts, heat damage, fitting distortion or damage, tag legibility, and any doubts that are held by the inspector. The sling shall be removed from service if deterioration is found.
  10. Slings removed from service that are not repairable shall be destroyed and rendered completely unfit for future use.
  11. Abrasion, heat damage or cuts to the cover may indicate a loss of strength to the core yarns. These slings shall not be used until evaluated by the manufacturer.


Properly maintaining a Twin-Path® synthetic roundsling during and in-between each use, is the best way to help extend its life and keep it in service. Take care of your gear and your gear will take care of you—it’s that simple.

Here are some best practices for keeping a Twin-Path® synthetic roundsling in great condition:

  • Store them in a cool, dry, and dark environment and hang them up to keep them off of the ground. Avoid storing them in extreme hot or cold conditions.
  • Avoid prolonged sunlight and UV exposure to prevent loss of strength.
  • Keep your synthetic roundslings clean. Continued exposure to oil, dust, dirt, and moisture can wear down the materials over time and also make it difficult to see and read the sling tag.
  • Do not store your synthetic roundslings in a chemically active environment. Chemically active environments can affect the strength of synthetic roundslings in varying degrees, ranging from little to total degradation. Consult your synthetic roundsling manufacturer before using in a chemically active environment.
  • Synthetic roundslings should not be used at temperatures in excess of 194° F / 90° C, or at temperatures below -40°F / -40° C.
  • When lifting material with edges, use edge protection or barriers to prevent cutting of the polyester jacket and yarn core.
  • If there are any questions about the proper way to store, maintain, and protect your Twin-Path® synthetic roundsling equipment, please contact the manufacturer.

Prior to each use, regular inspection of Twin-Path® synthetic roundslings for damage or irregularities is the best way to help avoid costly downtime and help to keep everybody on the job site safe. Routine inspection should be looked at as an investment that, over time, will help keep valuable equipment running and keep workers safe.

Should you have any additional questions or concerns about sling inspection, or the condition, usage, repair, or replacement of your synthetic roundslings, please contact us to speak with a Lifting Specialist near you.

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Copyright 2017. Mazzella Companies.
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Mike Close

Mike CloseMike Close

Content Manager at Mazzella Companies

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