The ABC of TPED ~ Guidance in applying the new TPED regulations to packaged gas bundle frames~

Forfar, May 2008. When new regulations are introduced to any industry there is an evolutionary period during which they are incorporated into the way that industry works. However, as with the introduction of change into any organisation, or group of organisations, this period follows a cycle of adjustment, confusion and transition before final acceptance. Here, Steve Robertson, of packaged gas handling specialist RITCHIE, explains how the application of TPED, the Transportable Pressure Equipment Directive, to the storage and transportation of pressurised gases can be likened to this process.

It`s important to stress that, while the industry overall is currently in the confusion and transition stage with regard to TPED, it is a directive that can be interpreted on an individual basis with nothing more than hard work, dedication and expert knowledge. The specifications which govern its use are long and reference a number of other directives, regulations and laws, such as ADR (the European Agreement on the international carriage of Dangerous goods by Road) and BS EN 13769. However, TPED was introduced for a valid reason - to make the industry safer.

The directive covers the transport of a huge range of pressurised equipment, including gas bundles, which is where companies like RITCHIE become involved. A gas bundle, by definition, is two or more cylinders joined together within a manifold and restrained within a frame. RITCHIE designs and manufactures the frame element of the bundle for a range of customers, including long standing clients Air Products, Linde/BOC and Dominion Gas.

Prior to TPED, the transport of such equipment was solely covered by BS EN 13769, which governed the design, manufacture, identification and testing of the bundle. When the British Standard was introduced it was initially a voluntary code of practice. Before this, onshore-only bundles were covered by BS 449 a specification primarily detailing the use of structural steel in buildings. At the time the view was that a bundle was a structural design. As a result of this long history, it`s easy to see why some engineers are uncertain about TPED.

Where the challenges lie

One of the confusing elements has been that different companies are interpreting the specifications in slightly different ways. The challenge for the storage, handling and logistics specialist is to interpret and apply them, on behalf of our clients, in a legal manner. In order to achieve this, a company has to have experts in ADR, BS EN 13769, DNV 2.7-1:2006, which covers the transport of gases offshore, and of course TPED itself.

Another challenge is to guide our customers through the natural denial process and into acceptance. Even products that used to be accredited under BS EN 13769 have to be tested again and, because the regulations are different, they may fail. As a result, it`s easy to approach TPED with the feeling that a storage and transportation rig, that a company might have been using for twenty years or more without incident, should be OK for further use. If you do approach TPED like this it becomes another hoop to jump through - because a previously fit for purpose unit now has to be replaced. A better way to view the process is as part of a continual improvement system. After all, even if it is a new hoop to jump through, being able to continue to transport pressurised gases across the EU is also a business benefit. However, it must be stressed that no reputable business would have supplied a rig that was unsafe in the first instance, so I can empathise with the hurdles the vast majority of good businesses are overcoming.

Even within RITCHIE there have been diverging opinions on the advantages and disadvantages of the directive. However, it`s predominantly seen as a positive thing. Because we have a vast amount of design expertise and thirty years of experience working with our clients on issues like this we perceive a competitive advantage in being able to say we are centre of excellence on the subject. Of course, we could just as easily have begun by saying it was a barrier to selling existing products, but that kind of negativity doesn`t get you very far in the face of an intractable EU directive!

Another of the ways the confusion in the industry is being expressed is through different viewpoints on compliance dates. One of the reasons for this is that the vast majority of the directive is concerned with other elements of transport and doesn`t touch on gas bundles. The best rule of thumb is that if a gas bundle has to be transported on the road network anywhere in the European Union from now onwards, it must comply with TPED. The only exception is that an offshore pack can be driven directly to the dockside for offshore use only without TPED certification. However, if it is stored elsewhere on route or diverted, it has to comply. This means the most practical thing to do is to ensure compliance in the first instance. If they do go offshore, the bundles must also be compliant with the appropriate standard, which is DNV 2.7-1:2006.

Of course, on its introduction, TPED was even new to the relevant competent bodies. At RITCHIE, we tend to work with either Lloyds, DNV or Apragaz, but some customers may wish to work with other competent bodies, which is fine by us providing they are UKAS (The United Kingdom Accreditation Service) approved (see side panel for a list of accredited organisations). Of course, when this happens it makes sense to ensure that all parties are interpreting the directive in the same way from the outset - a role which it is sensible for the transport and logistics specialist to manage. Furthermore, because TPED is a European directive covering the shipping of pressurised gases across the continent, it is vital that the interpretation is correctly communicated to all non-English speaking partner companies. If this is done correctly, TPED can become a passport to further European trade.

An opportunity to improve

If you are starting out on the road to TPED compliance, it can seem very daunting. However, the steps you have to go through can be easily described. That said, even when approached as part of a continual improvement process, the compliance and manufacturing procedure is by necessity quite complex. First, an expert independent structural engineer has to verify the bundle frame designs, and full calculations have to be supplied to him as a matter of course. At this stage the relationship with the competent body will need to be created, if it doesn`t already exist “ they will check over the design and either pass or fail it for use. However, they won`t comment on it as they aren`t consultants. As a result, you should always watch for over-engineering, which can add to the cost of manufacture - even if it increases the likelihood of a pass.

The next requirement is a facility in which to fabricate steel. Because the vast majority of units are destined for offshore use, particularly those needed by the readers of Hazardous Cargo Bulletin, DNV certification will be required. As a result, the fabrication of the units must be done by certified, professional coded welders and the appropriate ISO certificates, welding procedures and audit procedures must be in place. The relationship with the certifying body will be leveraged at this stage as well, because they need to do a number of tests during the welding process. These tests will be drawn from both TPED and DNV documentation for an offshore bundle that has to travel on the road network to reach its destination.

Following manufacture of the prototype, there are a number of other tests that will need to be performed. These ensure that a new or retested product meets the standards outlined in TPED and, while not entirely straightforward, they needn`t be rocket science. The process is based on a rotational drop test, to simulate the impact of a bundle falling from the vehicle that`s transporting it and a vertical drop test to simulate it being dropped by a forklift. In order to conduct the tests, you need to have the appropriate facilities in place, including a tilt rig to simulate the height of a wagon. This entire procedure must be witnessed by a competent body such as Lloyds, DNV or Apragaz. After being dropped, the manifolds must maintain its pressure without any leaks and the bundle frame must continue to safely contain the cylinders. The pressure used is normally five bar and it`s tested afterwards using a calibrated gage and a leak test. The weight of the gas is simulated with a water ballast. As anyone familiar with this kind of testing will already understand, the vertical drop test is the easier of the two to pass without any re-design or amendments.

If there`s more than 3000 litres of gas contained within the cylinders or 1000 litres in the case of toxic gas, the testing is no longer necessary - because the bundles are so large that the chances of them toppling are negligible. The largest bundle frame we`ve manufactured was a 64 cylinder unit. It sounds big but these jobs do arise - for instance oxygen storage units for diving gas require this kind of capacity.

In a sense, the best handling partner you could use would be one with extensive experience of getting it wrong in the early stages! While that`s a slightly glib thing to say, it does have a foundation in truth “ the bundles do get badly damaged in the early stages of testing the first designs. A specialist company with lots of clients in similar sectors will be able to transfer non-confidential information from one project to another to minimise the errors in the early stage of a new job. Indeed, the more unusual projects a company has worked on, the easier handling the next challenge becomes. Even we failed the test twice before we passed it “ like most things it`s a learning curve.

However, if DNV 2.7-1 is also involved, the process can be less arduous for long standing specialist companies who have built up a relationship with the competent body, thanks to a Manufacturing Survey Arrangement (MSA) that DNV can award. An MSA takes several years to achieve and states that its bearer is authorised to perform testing and inspection of containers during manufacture without the attendance of the surveyor. As a result, instead of having its products checked at every stage by a DNV assessor, they are only checked when the equipment is finished. It also allows the company in question to prepare a declaration of conformity, which will be the basis of product certificates issued by DNV. An MSA is reviewed by DNV every four years and, while there are other companies with similar arrangements, RITCHIE was the first UK business to be endowed with this status for 2.7-1. An MSA is a good example of how in-depth understanding of a regulation makes compliance easier.

As the MSA has illustrated in relation to DNV 2.7-1, acclimatisation to TPED will make its application more straightforward. Indeed, in change management terms, there are already signs that the transition period is drawing to a close and the acceptance phase is beginning in some companies. However, if this process is to continue, the industry overall needs to reach that final stage of acceptance and understanding that far from being just another hoop to jump through, TPED is an essential safety standard that can deliver positive business benefits.

Ends: 1918 words

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For further information contact: John MacAskill,
David Ritchie Implements Limited, Carseview Road,
Forfar, Scotland, DD8 3BT
Telephone: 01307 462271
Fax: 01307 464081
e-mail: jmacaskill@ritchie-uk.com
www: www.ritchie-uk.com

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Sydenham, London, SE26 4BT
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About RITCHIE: RITCHIE provides innovative handling solutions for the agricultural, offshore, industrial gas & chemical, defence, glass, distribution, automotive, rail and utility sectors. The business was established over a century ago and today employs over 120 people in Forfar, supplying businesses across the globe.