Posted by ptf on October 23, 2001 at 07:16:43:
The following article is with New Zealands version of OSHA and
Luxfers response. For the original site go to the 2 links
http://www.divenewzealand.com/53tank3.html
http://www.divenewzealand.com/53tank4.html
http://www.divenewzealand.com/53tank3.html
Are Aluminium Cylinders Safe
Interview with Kim Comben, Occupational Safety and Health
By Dave Moran
Kim, is OSH (Occupational Safety & Health Service) aware of the concerns amongst scuba
filling stations regarding certain cylinders?Kim, is OSH (Occupational Safety & Health Service)
aware of the concerns amongst scuba filling stations regarding certain cylinders?
Yes, OSH is aware of concerns from gas cylinder testing stations and filling stations in relation to certain
cylinders, specifically aluminium alloy dive cylinders. Sometimes problems can be limited to serial
numbers or batches, but in respect of the current concerns, it’s in relation to a specific specification,
which are DOT, SP and E 6498 cylinders. These are made from an aluminium alloy 6351 material, and
the problem that has been exhibited is a tendency for cracks to develop in the neck area which may lead
to rupture.
Has OSH made recommendations to filling and testing stations to prevent personal and
material injuries? No, but we have requested information from the testing stations on the numbers of
cylinders that they are failing, so we can build up a database. We have also assisted the industry where
requested in respect of determining faults in the cylinders insofar as actually giving explicit directives.
Noted deficiencies in the testing procedure of cylinders have been raised with NZU (New Zealand
Underwater) and the CTLA (Cylinder Testing Laboratory Association). One of those deficiencies is the
tendency, in some instances, of testing stations not cleaning the threaded area of the cylinder prior to a
visual examination, thus making it difficult to detect possible cracks.
Has OSH considered issuing a procedure standard for filling and testing tanks, as there seems
to be a wide variation in the way people test tanks?
There is already a standard in place for the testing of cylinders. The NZU have their own code of practice
for testing, and also IANZ (International Accreditation NZ, previously Telarc) accredited testing stations
follow the guidelines for testing gas cylinders in accordance with (Australian Standard) AS2337
specification.
Does OSH have a procedure in place where they check on filling stations to ensure that they
are using the correct methods to test cylinders?
At the moment, no. However, in respect of the current concern regarding aluminium alloy cylinders and
what we are learning, I think it is something we must focus on in the future in terms of educating people
filling cylinders, given that in many cases we will never see all the people that fill cylinders due to private
compressors etc that are being used. But this point has been highlighted as a result of events in the last
few months.
Has OSH considered issuing a standard or setting a standard for issuing licences to a person
to be qualified to test and fill cylinders?
Currently testing stations are required to have an approved signatory that oversees the work of their
station staff. We have noted that some test station staff are not at the desired skill level that we would
deem appropriate for the task. There are new regulations in the pipeline in respect of gas cylinder testing
stations, and one will probably be to ensure that the staff who actually carry out the test are fully trained
and competent, rather than being watched over by somebody who is. In respect of the filling of gas
cylinders, there are procedures on filling. We currently do not licence persons filling dive cylinders as we
do for flammable gases, but we would expect those persons that are filling to be aware of procedures for
filling and following the manufacturer’s recommendations, and in addition to that ensuring they are
charging the cylinders in accordance with the requirements of the Dangerous Goods Class 2 Gases
Regulation 1980. From time to time we act on complaints from customers, test stations or from the
agencies that accredit the test stations, namely NZU or IANZ, to carry out the policeman-type function in
investigations.
Can you comment on why there is a difference in the period of hydro testing? In New Zealand
and Australia it’s every two years, while in the USA it’s every five years.
We actually follow the original Australian requirements for gas cylinder testing. When our regulations
were written, steel dive cylinders were annually visualed and hydroed. Aluminium cylinders were visualed
annually and hydroed every two years. As time went on we got requests from the industry in respect of
steel cylinders, in that they would like a relaxation on the hydro test requirements. So we brought steel
cylinders in line with aluminium cylinders. In recent times, as a result of issues surrounding cracks in
cylinders, it’s my understanding that the Australians have now reverted back to an annual hydro and
visual on all dive cylinders. In the USA the current requirement is five years. I believe that the DOT may be
looking at extending it out to ten years; however, there is a strong industry-led campaign in the USA for
dive cylinders to get looked at on an annual basis. But there’s no actual regulation insisting on an annual
visual or hydro test in the States.
This seems a contradiction. Australia is looking at doing hydros every year, and the USA is
going up to every ten years? That signals a very confused message!
I can’t understand why DOT is looking at possibly extending it from five to ten years. In terms of what’s
happening in New Zealand, I remain comfortable with an annual visual, and a hydro every second year for
both steel and aluminium cylinders.
There have been discussions as to whether these cylinder cracks are visible or not, in other
words the crack is subsurface. Do you feel that the industry may need to look at more
sophisticated testing gear like ultrasound, which would require a higher skill level?
From a regulator’s viewpoint, yes, we are looking at the installation of examination equipment that will be
able to detect subsurface faults in cylinders. It may not necessarily mean that the actual person
conducting the test has to be any better skilled than they currently are. In fact it could be quite the reverse,
if a machine is used to find a fault and provide a readout. So maybe it would be a case of a person being
skilled in operating the machine, rather than actually being skilled in finding faults. I have asked one of the
manufacturers whether more sophisticated testing equipment is available for finding defects in cylinders.
Naturally if one moves to more sophisticated equipment there is a greater capital outlay, which may
ultimately lead to a rationalisation of testing stations in New Zealand.
Has OSH been in constant contact with the manufacturers of the faulty cylinders to make them
fully aware of the concerns that OSH has regarding these cylinders?
We have been in contact. CIG as a manufacturer of cylindrs doesn’t exist anymore, but Luxfer bought the
CIG plant, so whilst we speak to Luxfer, they tentatively represent the old CIG market. We’re speaking to
Luxfer Australia and Luxfer USA. I’ve asked certain questions at the moment, and I’m looking at bringing
the other manufacturers like Walter Kidde and Catalina into further discussions very shortly. I’ve
suggested a number of agenda items for discussion, and Luxfer Australia. They are sending a copy of
the agenda items to their sister company in the States. One of the individuals for Luxfer in the USA is the
chairman of the ISO committee for the testing of gas cylinders, and I have included into the proposed
agenda items like a finite life for cylinders.
I understand that on August 5-6 this year there’s going to be an industry meeting. Could you
expand on that?
The industry meeting is the Cylinder Testing Laboratory’s Association annual general meeting, in which
we have been invited to participate and contribute in respect of issues that have emerged in the last 12
months. It was my intention to invite Luxfer to speak at that meeting to give details of the findings from the
Tairua accident, and the ongoing investigation into the cylinders. Unfortunately, Luxfer are unable to
attend due to internal commitments on those dates, so it’s anticipated that later in the month there will be
a number of industry workshops both for CTLA and NZU stations.
How seriously is OSH looking at recommending that scuba cylinders have o finite life of 20
years?
We are looking at possibly putting a finite life on dive cylinders. We had seen problems with the 6498.
Some of the 3AL cylinders are now beginning to exhibit similar problems to the 6498, hence the reason
why the department is now saying it may be more appropriate to put a finish date on the life of the
cylinders. That’s one of the things we intend to discuss with the manufacturers. We are saying that when
cylinders reach the 20 years of age mark, regardless of whether they have been in the rental market or
recreational sector, they would be removed from service. The other thing that is beginning to emerge is
that many new cylinder ( not dive cylinders) designs are in fact beginning to stipulate the cylinder is fit for
service for a certain number of years, and after that it should be destroyed. New cylinders are entering
the industrial scene that have a finite life of 20 years. I suspect it would only be a matter of time before
such cylinders start to appear in the dive market.
Are testing stations procedures of a high standard?
It has come up, during the course of discussing faults of cylinders at cylinder testing stations, that the odd
station has confessed that they weren’t perhaps as thorough as they could have been when examining
cylinders. For example, they weren’t actually treating the threaded area with a cleaner prior to
examination, and as a result there was a potential that they could have missed cracks. In addition to this,
it’s also become apparent in respect of filling that some cylinders may have been overcharged above
their working pressures. Again, this will contribute to the stresses placed on the container which can
exacerbate the faults that are found therein. We see this as a matter of ongoing education for testing
stations, that they must test and fill in accordance with prescribed procedures.
Has OSH considered putting in place spot checks which will ensure that the test and filling
procedures are up to standard?
We rely very much on the auditing functions carried out by International Accreditation New Zealand (IANZ)
and the NZU. From time to time we do spot audits of testing stations to ensure that they are testing in
accordance with prescribed standards or procedures. However, like most government departments
these days, we are very resource-thin. It comes down to a matter of priorities in terms of what we’ve got
the time to do, and what resources we have available. I think in respect of the filling of cylinders, it’s
something we’ve got to look at more closely in the future. But again, whilst you can visit one day and
check, what’s preventing someone overfilling the next day? It all comes down to education of the person
on the job.
Yes, OSH is aware of concerns from gas cylinder testing stations and filling stations in relation to certain
cylinders, specifically aluminium alloy dive cylinders. Sometimes problems can be limited to serial
numbers or batches, but in respect of the current concerns, it’s in relation to a specific specification,
which are DOT, SP and E 6498 cylinders. These are made from an aluminium alloy 6351 material, and
the problem that has been exhibited is a tendency for cracks to develop in the neck area which may lead
to rupture.
Has OSH made recommendations to filling and testing stations to prevent personal and
material injuries?
No, but we have requested information from the testing stations on the numbers of cylinders that they are
failing, so we can build up a database. We have also assisted the industry where requested in respect of
determining faults in the cylinders insofar as actually giving explicit directives. Noted deficiencies in the
testing procedure of cylinders have been raised with NZU (New Zealand Underwater) and the CTLA
(Cylinder Testing Laboratory Association). One of those deficiencies is the tendency, in some instances,
of testing stations not cleaning the threaded area of the cylinder prior to a visual examination, thus
making it difficult to detect possible cracks.
Has OSH considered issuing a procedure standard for filling and testing tanks, as there seems
to be a wide variation in the way people test tanks?
There is already a standard in place for the testing of cylinders. The NZU have their own code of practice
for testing, and also IANZ (International Accreditation NZ, previously Telarc) accredited testing stations
follow the guidelines for testing gas cylinders in accordance with (Australian Standard) AS2337
specification.
Does OSH have a procedure in place where they check on filling stations to ensure that they
are using the correct methods to test cylinders?
At the moment, no. However, in respect of the current concern regarding aluminium alloy cylinders and
what we are learning, I think it is something we must focus on in the future in terms of educating people
filling cylinders, given that in many cases we will never see all the people that fill cylinders due to private
compressors etc that are being used. But this point has been highlighted as a result of events in the last
few months.
Has OSH considered issuing a standard or setting a standard for issuing licences to a person
to be qualified to test and fill cylinders?
Currently testing stations are required to have an approved signatory that oversees the work of their
station staff. We have noted that some test station staff are not at the desired skill level that we would
deem appropriate for the task. There are new regulations in the pipeline in respect of gas cylinder testing
stations, and one will probably be to ensure that the staff who actually carry out the test are fully trained
and competent, rather than being watched over by somebody who is. In respect of the filling of gas
cylinders, there are procedures on filling. We currently do not licence persons filling dive cylinders as we
do for flammable gases, but we would expect those persons that are filling to be aware of procedures for
filling and following the manufacturer’s recommendations, and in addition to that ensuring they are
charging the cylinders in accordance with the requirements of the Dangerous Goods Class 2 Gases
Regulation 1980. From time to time we act on complaints from customers, test stations or from the
agencies that accredit the test stations, namely NZU or IANZ, to carry out the policeman-type function in
investigations.
Can you comment on why there is a difference in the period of hydro testing? In New Zealand
and Australia it’s every two years, while in the USA it’s every five years.
We actually follow the original Australian requirements for gas cylinder testing. When our regulations
were written, steel dive cylinders were annually visualed and hydroed. Aluminium cylinders were visualed
annually and hydroed every two years. As time went on we got requests from the industry in respect of
steel cylinders, in that they would like a relaxation on the hydro test requirements. So we brought steel
cylinders in line with aluminium cylinders. In recent times, as a result of issues surrounding cracks in
cylinders, it’s my understanding that the Australians have now reverted back to an annual hydro and
visual on all dive cylinders. In the USA the current requirement is five years. I believe that the DOT may be
looking at extending it out to ten years; however, there is a strong industry-led campaign in the USA for
dive cylinders to get looked at on an annual basis. But there’s no actual regulation insisting on an annual
visual or hydro test in the States.
This seems a contradiction. Australia is looking at doing hydros every year, and the USA is
going up to every ten years? That signals a very confused message!
I can’t understand why DOT is looking at possibly extending it from five to ten years. In terms of what’s
happening in New Zealand, I remain comfortable with an annual visual, and a hydro every second year for
both steel and aluminium cylinders.
There have been discussions as to whether these cylinder cracks are visible or not, in other
words the crack is subsurface. Do you feel that the industry may need to look at more
sophisticated testing gear like ultrasound, which would require a higher skill level?
From a regulator’s viewpoint, yes, we are looking at the installation of examination equipment that will be
able to detect subsurface faults in cylinders. It may not necessarily mean that the actual person
conducting the test has to be any better skilled than they currently are. In fact it could be quite the reverse,
if a machine is used to find a fault and provide a readout. So maybe it would be a case of a person being
skilled in operating the machine, rather than actually being skilled in finding faults. I have asked one of the
manufacturers whether more sophisticated testing equipment is available for finding defects in cylinders.
Naturally if one moves to more sophisticated equipment there is a greater capital outlay, which may
ultimately lead to a rationalisation of testing stations in New Zealand.
Has OSH been in constant contact with the manufacturers of the faulty cylinders to make them
fully aware of the concerns that OSH has regarding these cylinders?
We have been in contact. CIG as a manufacturer of cylindrs doesn’t exist anymore, but Luxfer bought the
CIG plant, so whilst we speak to Luxfer, they tentatively represent the old CIG market. We’re speaking to
Luxfer Australia and Luxfer USA. I’ve asked certain questions at the moment, and I’m looking at bringing
the other manufacturers like Walter Kidde and Catalina into further discussions very shortly. I’ve
suggested a number of agenda items for discussion, and Luxfer Australia. They are sending a copy of
the agenda items to their sister company in the States. One of the individuals for Luxfer in the USA is the
chairman of the ISO committee for the testing of gas cylinders, and I have included into the proposed
agenda items like a finite life for cylinders.
I understand that on August 5-6 this year there’s going to be an industry meeting. Could you
expand on that?
The industry meeting is the Cylinder Testing Laboratory’s Association annual general meeting, in which
we have been invited to participate and contribute in respect of issues that have emerged in the last 12
months. It was my intention to invite Luxfer to speak at that meeting to give details of the findings from the
Tairua accident, and the ongoing investigation into the cylinders. Unfortunately, Luxfer are unable to
attend due to internal commitments on those dates, so it’s anticipated that later in the month there will be
a number of industry workshops both for CTLA and NZU stations.
How seriously is OSH looking at recommending that scuba cylinders have o finite life of 20
years?
We are looking at possibly putting a finite life on dive cylinders. We had seen problems with the 6498.
Some of the 3AL cylinders are now beginning to exhibit similar problems to the 6498, hence the reason
why the department is now saying it may be more appropriate to put a finish date on the life of the
cylinders. That’s one of the things we intend to discuss with the manufacturers. We are saying that when
cylinders reach the 20 years of age mark, regardless of whether they have been in the rental market or
recreational sector, they would be removed from service. The other thing that is beginning to emerge is
that many new cylinder ( not dive cylinders) designs are in fact beginning to stipulate the cylinder is fit for
service for a certain number of years, and after that it should be destroyed. New cylinders are entering
the industrial scene that have a finite life of 20 years. I suspect it would only be a matter of time before
such cylinders start to appear in the dive market.
Are testing stations procedures of a high standard?
It has come up, during the course of discussing faults of cylinders at cylinder testing stations, that the odd
station has confessed that they weren’t perhaps as thorough as they could have been when examining
cylinders. For example, they weren’t actually treating the threaded area with a cleaner prior to
examination, and as a result there was a potential that they could have missed cracks. In addition to this,
it’s also become apparent in respect of filling that some cylinders may have been overcharged above
their working pressures. Again, this will contribute to the stresses placed on the container which can
exacerbate the faults that are found therein. We see this as a matter of ongoing education for testing
stations, that they must test and fill in accordance with prescribed procedures.
Has OSH considered putting in place spot checks which will ensure that the test and filling
procedures are up to standard?
We rely very much on the auditing functions carried out by International Accreditation New Zealand (IANZ)
and the NZU. From time to time we do spot audits of testing stations to ensure that they are testing in
accordance with prescribed standards or procedures. However, like most government departments
these days, we are very resource-thin. It comes down to a matter of priorities in terms of what we’ve got
the time to do, and what resources we have available. I think in respect of the filling of cylinders, it’s
something we’ve got to look at more closely in the future. But again, whilst you can visit one day and
check, what’s preventing someone overfilling the next day? It all comes down to education of the person
on the job.
http://www.divenewzealand.com/53tank4.html
Are Aluminium Cylinders Safe?:
Luxfer's Comments
Picture: The tank that exploded in Tairau resulting in
Brian Schmidt losing a leg
We at Luxfer Gas Cylinders are grateful to Dive New Zealand for seriously
addressing the all-important issue of cylinder safety, and we appreciate
the chance to express our point of view.
For many years, Luxfer has consistently emphasized safe use of our products
through an active scuba safety education program, through our pioneering efforts
in the development of Visual Plus non-destructive testing equipment, and through
the most generous cylinder-replacement program in the scuba industry. We are
currently organising seminars in Auckland and Wellington in mid-August to
address directly the questions and concerns of New Zealand divers. However,
Luxfer (or any other cylinder manufacturer) can only do so much to promote safety.
Ultimately, safety is the responsibility of the individual diver, who must make sure
that cylinders, as well as other equipment, remain in proper operating condition.
Luxfer takes full responsibility for the high quality and dependability of every
cylinder that leaves our factories. Each cylinder is manufactured to specific, very
demanding international standards (eg DOT, AS and BS). Government inspectors
ensure that cylinders are thoroughly tested and approved before shipment. But
once a cylinder leaves the factory, Luxfer has no control over what happens to it -
and we have learned that, unfortunately, a great deal can happen to scuba
cylinders to make them unsafe. All too often, scuba cylinders are fast-filled,
over-filled, left filled at full pressure for long periods, left in the sun or in car boots,
dumped filled (sometimes several times a day), gouged and dented, stripped and
repainted, and generally mishandled or abused. All these conditions can shorten
the useful life of a cylinder. Like any other important piece of equipment,
high-pressure cylinders - whether made of aluminium, steel, nickel, composites or
other materials - require proper care, maintenance and handling. Well-maintained
cylinders can deliver decades of safe, reliable service. More than 30 million Luxfer
cylinders are currently in use around the world in a wide variety of demanding
applications.
To ensure safety, all high-pressure cylinders should be periodically inspected by
qualified, accredited inspectors and re-tested or re-qualified. Between re-tests,
cylinders should also be thoroughly visually inspected by trained, certified
inspectors. In most countries, the industry standard is a complete visual inspection
at least once each year. However, for cylinders in heavy service, Luxfer
recommends visual inspections at least every four months, as well as Visual Plus
inspections, if possible.
When discussing cylinder cracks and failures, it is imperative to make a
distinction between actual scientific findings versus subjective opinions and
proliferating myths. Luxfer is currently studying sustained load cracking in
aluminium cylinders made of 6351 alloy, and we have engaged respected outside
research organisations to assist in tests and analyses. Extensive international
research has shown definitively that cracks in these cylinders generally do not
grow quickly. For example, an independent research report (a copy of which is on
file with OSH) revealed that the cylinder which injured Brian Schmidt in the
much-publicized Tairua accident showed crack growth over a seven-year period. It
is logical to ask why this cylinder was not condemned by a qualified inspector long
before it became dangerous.
Unfortunately, we have found that there are a number of cylinder ‘inspectors’
around the world - including even experienced and well-meaning divers and dive
shop operators - who have not taken the time to learn proper procedures for
detecting cracks in aluminium cylinders. Inspecting aluminium cylinders is very
different from inspecting steel cylinders. For one thing, when checking an
aluminium cylinder, the inspector should initially focus on the threads, which is
where cracks occasionally start. Visual Plus testing equipment, which Luxfer
helped develop, offers a fast, reliable method for removing the guesswork from
crack detection; we highly recommend its use.
Divers have every right to be concerned about cylinder safety - in fact, Luxfer has
been encouraging that concern for many years. But the secrets to safety are
knowledge and prudence. We’d like to conclude our comments with a published
quotation from William L. High, president of Professional Scubu Inspectors, Inc
(PSI), a highly-respected, independent authority on cylinder safety who has
investigated cylinder failures around the world: ‘Perhaps the greatest
responsibility of all for safe cylinders lies with cylinder owners. They must
recognize that their cylinder contains over one million pounds of energy, that
prudent handling, care and usage will help keep that explosive force contained,
and they must insist that only trained professionals inspect, service or fill their
cylinder’ (Sources, September/October 1994, p41).