Eyebolts and eyenuts are used everyday in the lifting sector and changes to the Australian Standards will impact everyone. Charles Bell, Senior Lifting and Product Engineer, explains.
Last year saw the release of a new Australian Standard governing the humble collared eyebolt. Australian Standards have valuable guidance for users of lifting gear and AS2317.1-2018 is no exception. It contains extended detail for use as well as new requirements for markings and inspection. This new Standard concerns low tensile eyebolts and eyenuts, which are called grade 4 to align with international terminology.
The old familiar
Collared eyebolts are a simple device. They have an eye at one end which we can connect to our slings and a thread which we can connect to our payload at the other. While eyebolts themselves have changed little over the course of many years, the changes in the Standard are worth exploring.
Eyenuts are now included
The new Standard now includes comprehensive treatment of both eyebolts and eyenuts. Eyebolts have an external thread and eyenuts have an internal thread.
The thread is fundamental to a safe connection to the payload. These threads come in all shapes and sizes and are of course internal as well as external with the result that eyenuts are commonplace. The previous (1998) version of the Standard remained silent on the issue of eyenuts. Including them now enables the Standard to open up a more thorough conversation about the threaded connection in general. This is valuable because it is important that we get the connection right.
The substrate
It is vital that the threaded connection to the payload is safe and does not over-stress the supporting material with its threaded interface. AS2317.1 calls this supporting material the substrate.
Contained within the Standard are clearer rules to set out how strong the substrate material must be. A common pitfall is to fit an eyebolt to material which is simply not strong enough. One of the advantages of grade 4 (lower tensile) eyebolts is that when lifting softer materials, the grade 4 eyebolt can offer a larger thread to use with a soft payload. This is often at a lower cost than a high tensile lifting point of similar overall size.
Matching the strength of an eyebolt to its substrate is vital to achieving sufficient strength and the new Standard provides guidance on a variety of common scenarios such as: use of a nut behind a plain hole, use of reinforcing washers, and use with threaded studs. Common questions such as what grade of nut or stud to use and what tolerance on hole size is required are now addressed.
The importance of the collar
The defining feature of a collared eyebolt is of course, the collar. A dogger might instinctively make the distinction between a lifting eyebolt and something else purely upon the presence of the collar without giving much thought to what it does. Within the new Standard the role of the collar is now emphasised. When we use any collared eyebolt (or eyenut) it is important to understand what this means and how vital the ‘collar’ of the eyebolt is.
Wherever an eyebolt is loaded in line with the axis of its thread (in a straight line), the central threaded part can contribute fully towards resisting the lifting forces.
Wherever an eyebolt is loaded away from this axis, then the strength is greatly reduced and the collar with the support it provides becomes vital to resisting the lifting forces.
Without the support of the collar, damage in the form of a bent eyebolt is often the end result.
The new Standard provides clearer diagrams and instructions for avoiding this type of damage when the eyebolt collar cannot directly contact the payload, including the use of shims and packing washers.
Ensuring that the collar is fully supported by the payload (substrate) is important for other reasons too. For example, it provides a visual indication as to whether an eyebolt is unwinding itself.
The new Standard also provides guidance in order to avert such risks.
These are all examples of improved use guidance within the Standard, it is not possible to describe all of them here. Readers are urged to examine the Standard for themselves or to engage in suitable training on the subject.
The direction of loading
One of the most important changes to the Standard however is that it has addressed the differences between load rating methodologies that exist between low and high tensile eyebolts.
In general, good quality high tensile eyebolts around the world are marked with the worst case loading orientation in mind. With low tensile eyebolts however, practices vary – but the most common method is to mark the best case load rating – that is, a straight pull (axial loading).
The old Australian Standard (by the way) avoided this controversy and did not specify any WLL marking.
More terminology
In order to address the issue, the new Standard has clarified some terminology with the following terms:
Axial loading (which is a straight pull)
Lateral loading (which is a type of side loading that is never allowed)
Transverse loading (also called trunnion loading).
For straight line axial loading, some tolerances are given (because nothing is ever perfect). For axial loading to apply, the true direction of force needs to be within 5° of perfectly axial.
For transverse loading the Standard talks about the ‘plane of the eye’ and provides several diagrams to explain what this is.
Whenever eyebolts are subjected to loads that line up within the ‘plane of the eye’ this is an approved direction of loading. Again, the tolerance on perfect alignment with this plane is 5°.
Lateral loading
When eyebolts are subjected to loads that are outside of the plane of the eye, then this is called lateral loading.
Lateral loading is forbidden. The new term helps to avoid confusion of course, because people would sometimes call this ‘side loading’ and then on other occasions refer to transverse loading as side loading too!
Any load which is more than 5° outside of the plane of the eye is ‘lateral’.
Load rating markings
What does this mean for marking of WLL?
Well, if a load is applied axially – this is the best case loading and the WLL of the eyebolt is fully realised. For users that expect this and then refer to the load chart table for other loading directions there is no issue. For users that are used to high tensile eyebolts that are marked with their worst-case load rating this can cause confusion and problems.
The new eyebolt Standard takes account of this and now specifies additional markings. This takes the form of arrows, which must be applied to indicate the transverse load rating. Fortunately for owners of existing eyebolts and eyenuts with are large or high value there will generally be some potential to retrofit markings.
Inspection
We would be remiss at this point, if we fail to mention inspection. Extra guidance on use of eyebolts is useless if we are faced with damaged equipment to start with or if there are lifting assets on the books which clients, sites, and users don’t trust.
The old Standard made a distinction between eyebolts, which have a single purpose and stay dedicated to their payload and those that are loose gear, moving from job to job. The old Standard called these multi-use eyebolts ‘service eyebolts’. If there are eyebolts in your kit box, that’s what it means. The old Standard said that you should (that’s advisory) inspect them periodically.
The new Standard has gone further than this and now directs that service eyebolts shall (that’s mandatory) be examined periodically. It also applies an inspection interval table that is very much like one that appeared in the Chain Standard (AS3775.2:2014). Looking closely, what we find is that it is exactly the same. Importantly, because this sort of guidance can’t ever cover the extreme cases the table is advisory, not strictly mandatory. We all know however that in this context, advice is hard to avoid or ignore.
Where to from here?
It is not possible to cover all of the advice and additions contained within the Standard in this article. Users of eyebolts are urged to obtain a copy and familiarise themselves with the care and use section, obey load charts and follow manufacturer’s advice.
Remembering the basics
The very basic rule of eyebolts that everyone learns is that sometimes ‘eyebolts ain’t eyebolts’. The mysterious, the home-made and the oddball are still out there. We know they don’t comply and that they can be highly dangerous, precisely because much of the guidance in AS2317.1-2018 does not apply. In these cases, there is no rule change and the only options are to replace with a compliant eyebolt (an AS2318-2018 compliant one, or possibly a high tensile one) or to use a trusted engineered solution.