Revalidation Issues
Surrounding Cryogenic
Storage Tanks
Cryo Ops 2014
Paul Rowe
Wessington Cryogenics
Proven People, Products & Performance
UK / Overseas?
• This is based on several years discussions with
UK Gas Suppliers, Health & Safety Executive,
UK Insurers and the British Compressed Gases
Association (BCGA)
• It is now also being discussed within European
Industrial Gases Association (EIGA) so
potentially has wider implications / scope for
users of cryogenic tanks
• UK Gas suppliers are Global Gas Suppliers!
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Background
• Pressure Systems Safety Regulations 2000 (PSSR)
• British Compressed Gases Association Codes of
Practice :
• CP25-Revalidation of Cryogenic Static Storage Tanks
• TIS 23 – Internal Examination of Cryogenic Tanks
• GN17 - BCGA Policy and guidance for the safe filling of thirdparty owned and / or maintained tanks
• CP39 Mod 1-In-service Requirements of Cryogenic Storage
Systems at User Premises
• Company Insurance
• 3rd Party Independent Inspection Authority
• Health & Safety Executive
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PSSR & WPSE
• Legal requirement to develop a written periodic
scheme of examination for all pressure vessels.
• Mandatory in the UK since 1989 via previous
legislation / 2000 in current form
• Competent person must be satisfied that the
vessel is fit for purpose and safe to operate at
the designated operating conditions – not just
the fact that ‘its always been like that’
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BCGA CP25
• Code of Practice – not statute. However, if something
goes wrong, expect the HSE to ask why you were not
following best practice! ‘No Win, No Fee’ solicitors may
ask some awkward questions!
• BCGA Codes of Practice are adhered to by all the major
UK gas supply companies and more and more insurance
companies are becoming aware of them
• Good, sound engineering advice intended to keep the
user of such equipment safe.
• Scope originally aimed at bulk static / fixed tanks. This
was removed and essentially should cover all vessels
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Scope of CP25
• To provide guidelines for the periodic examination of
cryogenic tanks which can be incorporated into either
Written Schemes of Examination under PSSR , or
company maintenance and examination records
• Covers the revalidation of static tanks specifically
designed for the purpose of storing cryogenic liquid
– No volume criteria is given!
– No pressure criteria is given!
– No definition of ‘Static’ is given!
• CP25 remains valid, but will become obsolete with the
full publication of CP39 and all modules, plus various
other Codes of Practice – replaced by TIS 23
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Technical Information Sheet TIS23
• For tanks designed, manufactured and inspected in
accordance with a recognised code, operated and maintained
for cryogenic service, with the absence of failure mechanisms
outlined, the probability of failure is extremely low.
• This is a clear statement supporting the industry conclusion
that correctly designed, constructed, approved, operated and
maintained cryogenic tanks do not deteriorate in service and
therefore internal examination and proof pressure testing are
not required.
• The BCGA will continue to collate the results of inner vessel
examinations in support of this policy for static tanks and
update the data tables in Appendix 1 on a periodic basis.
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Technical Information Sheet TIS23
• Policy regarding internal examination and proof pressure
testing of static cryogenic liquid storage tanks
• A BCGA / Gas company response to HSE requests that
there should be a means of internal examinations of
cryogenic tanks
• Notable by their absence are reference to dewars and
vessels! All the supporting evidence is solely bulk,
stationary storage tanks!
• Have you ever had a small mobile vessel / dewar that
needed an internal repair?
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Guidance Note GN-17
• This document defines a gas supplier’s
responsibilities when intending to fill a third
party owned tank, used for the storage of
refrigerated liquefied gases (typically
nitrogen, oxygen, argon and carbon
dioxide) at a customer’s premises.
• BCGA Policy is that no Member shall fill a
tank until it has established that it is safe
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First fill
• The gas company will :– Full set of physical checks on the vessel, the
area, vessel documentation etc
– Check customer understands his
responsibilities under PSSR
– Customer understands operation of vessel
and how to report any changes
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Subsequent Fills
• The gas company will :– Undertake such checks as they deem reasonable to
ensure that the tank remains safe to fill
– Review any reported problems
– Require the customer to take prompt action if the tank
is in breach of PSSR and take action to make safe
– Check the vessel has been revalidated if >20 years
old
– Potentially suspend deliveries
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CP39 Module 1
• Scope :– Covers the in service requirements of
cryogenic storage systems of :•
•
•
•
Storage tank
Vaporiser
Control manifold
Interconnecting pipe work
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Revalidation to CP39 Mod 1
• The revalidation of a tank as fit for continued
service shall be based upon periodic reviews of
documentation carried out by the Competent
Person.
• The revalidation process shall comprise the
following steps :-
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Revalidation
• Review of design documentation
• Review of service history records(incl. all
pressure excursions)
• Review of external examination records
• Review of experience of similar tanks
• Confirmation that an APEA has been carried out
• Preparation of revalidation report
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Ageing Pressure Equipment Assessment
• An appropriate APEA should be completed by
the Competent Person prior to putting the
system into service
• Prior to the WPSE, it is essential to consider the
effect of ageing on the pressure equipment
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Documentation & Records
• New equipment to comply with PER & shall have all
appropriate documentation retained for life
• Old equipment shall have the documentation as required
by the applicable regulations at time of manufacture
• All of the above shall be available to the competent
person to produce / complete WPSE
• Where not available, the competent person may require
that a process of revalidation be undertaken prior to
confirming suitability of the equipment for continued
service – which process? CP25?
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Deficiencies
• Any deficiencies identified in the reviews
of design, service history or examination
records shall be assessed by the
Competent Person.
• Any deficiencies and the conclusion of the
assessment shall be recorded in the
revalidation record
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Supporting Information
• Where the original tank construction dossier or service /
examination records are incomplete the Competent
Person shall decide upon the appropriate action required
to revalidate the tank.
• Complete and original construction drawings in
conjunction with information from the tank nameplate
may suffice where full construction dossiers are
unavailable
• In extreme cases an internal examination of the tank, or
of a similar tank, may be necessary to establish base
line data for this and future revalidations – cost effective?
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Frequency of Revalidation
• The frequency of revalidation shall be decided by the
Competent Person but shall not be less than once in 20
years
• Remember, 20 years was referenced for bulk static
tanks! Consideration should be given for reduced
frequency for mobile vessels.
• Wessington’s own guidance is that the frequency should
reduce to 5 years after this initial period (for ADR road
transport tanks, from new, a full inspection is required
every 5 years!)
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Example vessel currently at
Wessington awaiting repair
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Typical Vessel
• 160 litre, 3 bar self pressuring liquid nitrogen
vessel
• Manufactured ‘?’ years ago (unknown!)
• User does not have original design dossier / test
certificate / drawings
• Minimal information available on the vessel data
plate
– Ie no design code stated, MAWP / design pressure
info, temperature
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Referring to that specific
vessel…
• Comment from 3rd party independent
inspection engineer from Lloyds,
employed by Wessington to review our
new build tanks :– “I wouldn’t touch it with a bargepole!”
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General Comment from HSE
• Comment from Health & Safety Executive
pressure vessel expert :– “Do not use the vessel until it has been fully
revalidated / I expect to see a comprehensive
data plate & test certificate”
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Previous Vessels Are No Better!
No dossier!
No data plate!
No drawings!
No operating
instructions!
Nothing to
work from!
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What Next?
• If you have such equipment in operation, you need to
ensure that your insurance company is aware of the
vessels, and that they have all the relevant test
certificates / vessel dossier.
• Is the data plate in good condition / legible?
• Can you really revalidate the tank based on the
information available to you?
• Gas companies are aware of this and are increasingly
pushing this issue
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What next?
• Wessington have to take a pragmatic stance – although
we are prepared to repair any manufacturer’s cryogenic
pressure vessel, we see it as only right to follow all the
current rules, regulations, codes of practice, gas
company internal interpretations of rules, comments from
3rd party engineers and the HSE
• We will not be repairing vessels what our own 3rd party
inspectors say they would not touch with a bargepole!!
• Should you or anyone else?!
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Thank You
Paul Rowe
Wessington Cryogenics
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