1. M
ANAGEMENT OF
ageing plant is never
easy. Tight budgets and
scarce labour resources
following seven years
in recession have not made tank farm
management any easier.
Also, ever tightening legislative
compliance keeps everyone on their
toes. It only takes an event like
Buncefield or the recent accident in
China to remind us how important it is
to keep employees and assets safe.
56 STORAGE TERMINALS MAGAZINE
PREVENTATIVE MAINTENANCE
STAYING IN
TIPTOP SHAPE
Preventative maintenance is key to identifying malfunctioning
equipment before an incident happens
Well-maintained facilities do not
suffer unplanned outages or fines
and the associated bad press by the
Environment Agency or the Health and
Safety Executive (HSE). Furthermore
the quality of stored product remains
at a premium, resulting in minimal
production issues and product quality
does not decline.
It is an unfortunate reality that most
catastrophic incidents follow a number
of ignored near misses.
Those who have attended one of
Assentech’s technical seminars will see
at first-hand how 20 mbarg will not
burst a balloon but can lift a 6 tonne
tank off its base. Keeping your plant
in tiptop shape is imperative and will
ensure a safe working environment.
You will also benefit from compliance,
minimal downtime and maximum
profitability.
One of the keys to success is
maintaining the condition of the
equipment and this can be achieved
through the development of a

2. 59STORAGE TERMINALS MAGAZINE
PREVENTATIVE MAINTENANCE
preventative maintenance plan. An easy
to follow programme can be designed
to fit any type of site by following some
simple guidelines and setting up routine
inspections. Failing components will
be identified and corrected before an
incident occurs and the site operating
efficiency will be maintained.
Preventative maintenance plans and
structured key performance indicators
are designed to address issues of
malfunctioning and underperforming
equipment before an incident occurs.
This strategy is a well-trodden path with
high pressure relief equipment following
many years of legislative development.
A systematic and structured
maintenance procedure of low pressure
systems is less uniform between
operators. The HSE is increasing
focus and awareness of safety and
management of ageing assets by
promoting the importance of following
a structured process.
The most comprehensive preventative
plan should be developed for each
piece of equipment. Once the piece
of equipment has an asset number it
is necessary to review its suitability
for the intended service. This review
can be achieved by reviewing the
service manual, performance curve(s)
and test certificates. The distributor
or manufacturer can assist with this
process. The maintenance regime
must include information on inspection
intervals and the lubrication schedule.
With the recommended information
in hand, the plan can be tailored to fit
the usage of the equipment and/or the
site standards.
Other criteria can determine the
timeframe and frequency of equipment
detailed on your maintenance plan and
these include:
Construction Quality and
suitability of the
original fabrication
and installation
Design Life limiting factors
assumed at design
stage
Design quality
Calibration
Documentation
requirements
Suppliers Obsolescence of
equipment
Operation Operating within
design limits
Inspection Visual inspection for
deterioration
Modifications Any modification
or change from
original scope

3. 61STORAGE TERMINALS MAGAZINE
PREVENTATIVE MAINTENANCE
RELEVANT STANDARDS
AND REFERENCE
● EEMUA Publication 231
Ed 1 – The mechanical integrity
of plant containing hazardous
substances
● EEMUA Publication 159 –
Users’ Guide to the Inspection,
Maintenance and Repair of Above
Ground Vertical Cylindrical Steel
Storage Tanks
● EEMUA Publication 217 Ed 1
– Safe and Effective Operation of
Storage Tanks
● EEMUA Publication 213 Ed 1 -
Emission reduction from Oil Storage
Tanks and loading operations
● HSG 176 – The storage of
flammable liquids in tanks
● API 653 – Tank inspection, repair,
alteration and reconstruction.
● API 2000 – Venting Atmospheric
and Low-pressure Storage Tanks
Buncefield Major Incident
Investigation Board http://www.hse.
gov.uk/comah/bouncefield/fuel-
storage-sites.pdf
● RR760 – Mechanical integrity
management of bulk Storage Tanks
● BS EN 14015:2004 – Site built
flat bottomed atmospheric
Storage Tanks
● ISO 28300 – Venting of
atmospheric low pressure
Storage Tanks
Breather valves are no exception. A
simple visual inspection is no longer
accepted by the HSE. Servicing breather
valves is not the most enthralling part of
the maintenance routine, but if they are
not looked after they could lead to the
plant being closed, a fine by the HSE or
worse still, harm to employees or loss
of life.
Every company needs to ensure its
valves are functioning as well as they
can. They need to be calibrated, leakage
tested and certified as fully functional.
Otherwise the consequences can be very
dangerous and expensive.
Assentech recently assisted a
customer in reducing their annual
nitrogen costs which were in excess
of £250,000 a year. After an expense
of £15,000 for replacement valves
and calibration, the company saved
the customer an estimated £90,000 in
nitrogen loss for the year.
Breather valves lose their ability to
seal over time. Assentech often inspects
valves that have had weight added to
the pallet assembly to compensate for
poor sealing. This is a very dangerous
correction and could result in a tank
collapse. This would only be flagged by
a weight test which is part of the valve
calibration protocol but the subsequent
HSE investigation would centre on why
the weight was added, by whom and for
what reason.
The conservation of vapours and
minimising of water ingress are key
elements in sustaining the quality
of stored liquids. Storage tanks are
typically large volume low pressure
vessels so the provision of tight sealing
and adequate vapour/air exchange is
essential. An efficient breather valve
safely conserves vapours up to the
maximum allowable working pressure.
Servicing and maintaining valves
isn’t rocket science, but it does need
specialist knowledge on how breather
valves work and are calibrated.
Assentech’s calculation methods
are third party verified which gives
customers peace of mind. Assentech
focuses on the valve as part of the
business process. Properly maintained
breather valves can save an operator a
huge amount of money and time.
The company can service and
calibrate many brands of breather valve
and is the UK’s only Groth service
centre and one of only two Europe-
wide. It is fully certified to calibrate and
leakage-test its full range of breather
valves onsite and at its fully equipped
service centre. This approach is essential
to the safe and efficient running of a
higher tier COMAH site.
This article was written by Assentech
Limited, a supplier of equipment,
services and technical expertise in
the fields of tank storage and process
safety. www.assentech.co.uk