Worcester Greenstar Heatslave 12/18 Technical Information page 17

External tank installations
Building Regulations – England and Wales
In England and Wales installations in single family dwellings
must comply with Building Regulations Part J. This in turn
requires compliance with BS 5410 : Part 1 : 1997 and
Part 2 : 1998. All tanks deemed to be at risk or with a
capacity of more than 2,500 litres will require a bund.
Building Regulations – Scotland
In Scotland Building Regulation part F applies. This in turn
requires compliance with BS 5410 : Part 1 : 1997 and
2 : 1998. All tanks deemed to be at risk or with a capacity
of more than 2,500 litres will require a bund.
Northern Ireland
In Northern Ireland the building regulations do not cover
the installation of Oil storage tanks, guidance should be
sought from BS 5410 : Part 1 : 1997 and Part 2 : 1998.
Bunds – when are they necessary?
These are 'enclosures' designed to contain spillage from the
oil tank. Reference must be made to OFTEC – Technical
information note T1/133 covering the risk assessment of
environmental damage being caused by spillage from oil
storage tanks to determine if a bund is required.
There are two main ways to comply if a bund is required:
1. Bunded tanks – are now the most popular way in which
to meet the standards and regulations if a bund is
required, these tanks are in essence a 'tank within a
tank' which prevent leakage from the inner 'oil' tank
escaping into the environment by containing it in the
outer tank. The use of these tanks avoids the work of
constructing a masonry or concrete wall bund as in
point 2.
Integrally bunded plastic tanks must comply to OFTEC
Standard OFS T100 and integrally bunded steel tanks
must comply to OFTEC standard OFS T200. Both must
have an OFCERT license to show compliance.
2. External bunds are masonry or concrete enclosures built
around a single skinned plastic or steel tank and lined
with an oil resistant material to contain the spillage. The
bund must be constructed to CIRIA report 163.
Both of these bunds must be capable of holding 110% of
the contents of the tank in the event of a leak or spillage
during filling.
32
The following criteria must be considered before choosing
the type of oil tank and its location:
British Standard 5410 : Part 1 : 1997 does not require tanks
installed externally to be fitted with a bund unless its
absence creates a hazardous situation. OFTEC has
published a risk assessment form T1/133, which lists the
requirements to be met if the tank is not to be fitted with a
bund. The risk assessment must be completed in all cases.
The assessment must be completed by an OFTEC approved
technician. The below situations would require the
provision of a bund in all cases:
1. Tank capacity in excess of 2,500 litres.
2. Tank sited less than 10 metres from controlled water.
3. Tank sited where spillage could run off into an open
drain or to a loose fitting manhole cover.
4. Tank within 50 metres of a borehole or spring.
5. Tank on hard surfaced ground that could enable spillage
run off to reach controlled water.
6. Tank sited in a position where the vent pipe outlet is not
visible from the filling point.
7. Tank supplying heating oil to a building other than a
single family dwelling.
8. Any other potential hazard individual to the site.
Internal tank installations
Always inform the local Fire Officer and Insurers of any
internal installations.
Oil tanks installed internally must never be sited in a
habitable area and must be within an enclosed chamber.
This chamber comprises a fully enclosed ventilated space
and must have 60 minute fire resistant wall, floor, door and
roof with a self closing door that opens outwards. The door
must be able to be opened from the inside without the aid
of a key. The chamber must act as a bund so the door must
open above the top level of any constructed bund. If the
use of an internally bunded tank is made then the chamber
only has to provide the correct fire protection, the door can
be at floor level. The chamber must be vented directly to
open atmosphere. Space for access to the tank in the
chamber must be provided. In the case of steel tanks
adequate space for painting and maintenance is required.
Any electrical lighting should be of the bulk head type with
switches mounted externally.
Oil storage tanks may be installed in a garage but the
guidance in OFTEC Technical sheet T1/127 must be
followed.
Underground tank installations
All underground oil storage tanks must be fitted with
overfill protection.
In all cases the potential buoyancy of the tank should be
considered if the water table in the area can rise above the
level of the oil in the tank.
Underground installation can be located closer then
1,800mm to an adjacent building and 760mm to a boundary
without additional protection.
All underground tanks must be specially constructed to
withstand the pressures placed upon then by the
surrounding ground. GRP tanks in either single or double
skinned versions are suitable, Polyethylene models are also
suitable. If steel tanks are used they must be of the double
skinned type.
Steel tanks
Steel tanks are available but are being out dated by
maintenance free plastic tanks due to their need for siting
on piers and painting.
They must be positioned with a slight back fall away from
the oil outlet (40mm per metre) to the drain/sludge cock at
the opposite end to enable any water or sludge to be drain
out of the tank.
Steel tanks should be constructed to comply with OFTEC
Standard OFS T200 and must be covered by an OFCERT
license.
Galvanised steel tanks and pipework should never be used
in oil storage or supply.
Plastic tanks
Plastic tanks do not require painting and can be sited
directly onto the ground (no need for piers) as they do not
suffer from corrosion, although the head of oil above the
boiler's burner should always be considered and access for
cleaning the oil filter and water trap be available.
Plastic tanks should be constructed to OFTEC Standard
OFS T100 and must be covered by an OFCERT license.
Position in relation to buildings and boundaries
The position of the oil storage tank relative to buildings and
boundaries needs consideration in terms of fire protection,
the storage tank itself does not constitute a fire hazard but
needs protection from a fire which may originate nearby.
For Class 1 installations, as mentioned earlier, no special
fire protection is needed if the tank is situated more than
1,800mm away from the building and not less than 760mm
from the site boundary.
Figs. 1 to 6 illustrate the requirements of a Class 1 tank
installation in relation to buildings (combustible wall and
non combustible wall) and boundaries (combustible and
non combustible).
33