One of the presentations at the recent Crane Safety Conference held in London earlier this year dealt with the dangers of third-party tower crane components, and was delivered by Christoph Schneider of Liebherr (Cranes Today July p29). In his presentation Schneider warned of the large number of pirate tower crane components that are now being produced, often in the Far East, and sold at very low prices as genuine items.
He then set out the results of independent tests Liebherr commissioned on third party tower sections and other components for Liebherr tower cranes. These presented a horrifying picture of under-strength materials, poor welding and short fatigue life, highlighting the danger of incorporating these components into a tower crane as, to use a well-worn cliché, ‘a chain is only as strong as its weakest link.’ The message from Liebherr was that tower crane owners should ensure that they only purchase genuine Liebherr components directly from Liebherr. But whilst this approach provides a means of ensuring that new components are genuine, it does nothing to address the issue of second-hand components already in circulation.
The presentation highlighted the issue of pirate components and as a consequence, the UK construction press has recently published several articles on the problem. These articles suggest that the problem of substandard third party components is not confined to Liebherr alone and that most other European tower crane manufactures are experiencing similar difficulties with unauthorised components in circulation. A particular problem is that the copies look so convincing that it is hard to tell them from the genuine article. According to Schneider, even the Liebherr tower crane factory has some difficulty with this as the pirates copy the Liebherr identification plates and marking systems.
During the discussion that followed the Liebherr presentation it was suggested that Radio Frequency Identification (RFID) could be one answer to the problem of establishing the true identity of components. Fitting each new component at the time of manufacture with a tag containing a unique identification number would enable owners to contact the manufacturer and easily establish that a component was genuine.
RFID is a general term used to describe a system that transmits the identity (in the form of a unique serial number) of an object wirelessly, using radio waves. The object is fitted with a tag containing a unique code which can be interrogated with a reader which sends and receives radio frequency (RF) data to and from the tags via an aerial or antenna. Information from the reader is then fed to a host computer for processing and storage.
The advantage of radio frequency waves, rather than the light used by the barcode scanners used in supermarkets, is that data can be read over a distance of several metres and does not require line of sight. Consequently data transfer is not affected by paint, grease, corrosion or water, all of which are often present on tower crane components.
The RFID tag fitted to the object to be identified contains a tiny radio device with a simple silicon microchip (typically less than 0.5mm across) attached to a small aerial and mounted on a base material. The whole device can be encapsulated in various materials, depending on the application and the degree of protection required. Tags come in two forms, active and passive. Active tags are battery powered and transmit a signal to the reader, often over distances of 100m. Passive tags do not contain a battery, but instead draw their power from signals transmitted by the reader. They can only be read over distances of about 3m. Active tags tend to be larger and more expensive than the passive type.
There are several versions of RFID that operate at different radio frequencies. The choice of frequency depends on the application—it is not a technology where ‘one size fits all’.
Three primary frequency bands are being used for RFID:
• Low frequency (125/134kHz): Most commonly used for access control, animal tracking and asset tracking.
• High frequency (13.56mHz): Used where medium data rate and read ranges up to about 1.5m (5ft) are acceptable. This frequency also has the advantage of not being susceptible to interference from the presence of water or metals.
• Ultra high frequency (850mHz to 950 mHz): Offers the longest read ranges, of up to 3m (10ft), and high reading speeds.
RFID is a fairly mature technology, having been around for over twenty years, and is currently used in a wide range of applications such as access control, manufacturing automation, logistics and distribution, retail, maintenance and product security. Even London’s Heathrow Airport is starting to use baggage trolleys fitted with RFID tags so that missing trolleys can be located and moved to where they are needed. For items that can be shipped to any part of the world it is important to ensure that communication protocols between tags and readers follow a standard format so that data can be read easily. There are now a number of international standards produced by both ISO, the international standards body and EPCglobal, an industry-based RFID organisation.
Tower crane components are generally stored, transported and used in harsh conditions. The RFID tags used to identify them would have to withstand a wide range of temperature, humidity and shock loading and be located in a secure position. Standard tags are now available with a temperature range of -20°C to + 150°C and are environmentally sealed to IP67. Technologies such as N-Metal have also been developed for ‘Thru-Metal’ RFID which enables tags embedded in metallic object to be read, despite the tendency of metal to act as a shield to radio waves. These are now used in many areas, such as tracking surgical instruments, tracking beer kegs and, most significantly for tower crane components, in the oil and gas industries, where they have been used to manage high value assets both topside and in harsh downhole environments.
RFID tagging of tower crane components by the manufacturer would not only ensure that each component had a unique identity enabling it to be identified as a genuine item produced by the tower crane manufacturer, but would also help tower crane owners to manage their assets more efficiently. Currently most tower crane owners just know that they own a given quantity of tower sections of a given type, they do not know either the identity of individual sections or where they are located, which makes stocktaking and asset control an onerous task. This lack of identity also makes it difficult to record the usage and maintenance of each component, which may well become more of an issue in the future with the current public concern about tower crane age.
RFID is not just limited to the passive identity of assets. Data can be written to the tag by the reader to record, for example, maintenance information or thorough examination dates so that information is stored on the item itself rather than at a remote location. This raises the possibility of a competent person carrying out a thorough examination, being able to access and capture information on each of the components making up a particular tower crane on a site. Such information would enable the competent person to concentrate on the areas of the crane where history indicated that potential problems could occur.
One note of caution is that, like most technologies involving electronic data, RFID tags can be easily cloned, and so should not be relied upon as the only means of authentication: Disreputable firms could copy tags and pass off counterfeit duplicates as originals.
One approach to strengthening RFID as a means of authentication may be to link the tag numbers to the age and type of component in some way, which would only make sense when combined with the manufacturer’s database.
It has been suggested that other authentication technologies such as microtagging (which utilises laser etching, microdots or materials with unique specifications) might be used. The disadvantage of these systems is that they are designed to be verified only by forensic inspection, so cannot be used for routine stock tracking. Again, no technology is totally secure and even microtags may themselves eventually be duplicated by ingenious pirates.
So far this article has concentrated on tagging of components by the tower crane manufacturer, but if manufacturer tagging was started tomorrow it would still be many years before all tower crane components in use were tagged. To obtain the maximum benefit from tagging, tower crane owners should actively consider RFID tagging of their existing fleet. This would have the dual benefit of allowing them to monitor and control their stock and, with the assistance of the crane manufacturers, provide proof that they are genuine components.
This proof would not only provide reassurance about a tower crane’s structural integrity but also ease the process of selling surplus components. The second-hand tower crane market is well developed, particularly as delivery times for new cranes and components are becoming extended, due to the current high demand. An inevitable result of the current concern over poor quality third party components is that sellers of second-hand tower crane components will need to be able to prove the provenance of the items they are selling.
In conclusion, it would appear that RFID offers the potential to both identify genuine components and provide tower crane owners with a means of identifying and controlling their assets. It seems to be a technology that is well worth further investigation by tower crane manufacturers and owners alike.
To learn more
Further information on RFID can be found on the RFID Centre’s website www.rfidc.com and the UK RFID providers’ trade association AIM UK at www.aimuk.org
A farmer scans a cow with an RFID indicator A farmer scans a cow with an RFID indicator RFID clip in cow’s ear RFID clip in cow’s ear RFID scanners detect RFID chips with radio waves. Energy from the scanner antenna powers the chip to respond. The computer-connected reader processes the chip’s signal. How RFID works
