BS 799-5:2010 Oil Storage Tanks from Abbotts – Square ?

BS 799-5:2010 Oil Storage Tanks ?

Abbotts have been making cylindrical pressure vessels since 1870. Recently we have expanded our range – quite literally 'broken the mould' –  and made some SQUARE ones! 

However as the client needed ISO9001, traceable materials with impact tests, Coded welding with approved procedures, NDT and all that good stuff it fell into our court.

                                                            

These single-skinned diesel fuel storage tanks are designed in accordance with BS799 PT5 Type J and are internally braced. Manufactured in carbon or stainless steel, they have a closed top and are supplied with a removeable stand and a bolted manway cover. An internal coating of oil, and a tough 3-pack external coating complete the look for these beauties but other finishes can be supplied as per customer requirements. Abbotts can also supply your accessories and fittings. 

Please ring or email us now with your enquiries – info@abbottpressurevessels.co.uk   Tel: 01636 704208

 

Here below is a whole heap of information about the design of these tanks for the brave  technically minded types who like that sort of detail:

Oil burning equipment-
Part 5: Carbon steel oil storage tanks Specification
nce publication

c:
BS 799-5:2010
Contents
Foreword iii
1 Scope 1
2 Normative references 1
3 Terms and definitions 1
4 Information to be supplied by the purchaser 3
5 Service tanks 3
6 Primary storage tanks 5
7 Manholes 19
8 Inspection openings 19
9 Tank oil heaters 20
10 Oil level indicators 21
11 Sludge removal connection 21
12 Filling pipe and delivery hose connections 21
13 Vent pipe connection 22
14 Vent pipe 22
15 Outlet connections and pipes 22
Annexes
Annex A (normative) Methods for pressure testing of service tanks and
primary storage tanks 24
Annex 8 (informative) Avoidance of overfilling of oil storage tanks 25
Bibliography 30
list of figures
Figure 1 -Relationship between design pressure, pitch of stays or
stiffening and plate thickness for rectangular service tanks of type 54
and rectangular primary storage tanks of types Ill, J and K 8
Figure 2- Relationship between design pressure, span between
supports and plate thickness for rectangular primary storage tanks of
types Ill, J and K 9
Figure 3- Shallow dished and flanged end 10
Figure 4- Dished and flanged end 11
Figure 5- Positions of steel cradles for primary storage tanks of
type I 17
Figure 6- Positions of steel cradles for primary storage tanks of
type II 17
Figure 7- Positions of cradles for primary storage tanks of types A, B
and C 18
Figure B.1 -Graph showing pressure developed when a tank is
overfilled with oil of classes CorD at a filling rate of 500 Umin and at
a viscosity of 16 mm2/s (relative density 0.84) 26
Figure 8.2- Graph showing pressure developed when a tank is
overfilled with oil of classes CorD at a filling rate of 1 000 Umin and
at a viscosity of 16 mm2/s (relative density 0.84) 27
Figure 8.3- Graph showing pressure developed when a tank is
overfilled with oil of classes E, For Gat a filling rate of 1 000 Umin and
at a viscosity of 370 mm2/s (relative density 0.935) 28
Figure 8.4- Graph showing pressure developed when a tank is
overfilled with oil of classes E, For G at a filling rate of 1 000 Umin
and at a viscosity of 860 mm2/s (relative density 0.946) 29
List of tables
Table 1- Maximum diameter or major axis and minimum thicknesses
of the shell and ends for service tanks of types 53 and 55 4
Table 2- Maximum diameter and minimum plate thicknesses of the
shell and ends of primary storage tanks of types I and II 7

BS 799-5:2010

Table 3- Minimum plate thicknesses for primary storage tanks of
type A 10
Table 4- Minimum plate thicknesses for primary storage tanks of
types Band C 11
Table 5- Minimum plate thicknesses for primary storage tanks of
typeD 72
Table 6- Minimum plate thicknesses for primary storage tanks of
types E and F 13
Table 7- Minimum plate thicknesses for primary storage tanks of
type G 14
Table 8- Dimensions of steel cradles for tanks of type I 77
Table 9- Dimensions of steel cradles for tanks of type II 17
Table 10- Dimensions of steel cradles for tanks of types A, Band C 18
Table 11- Manholes- Minimum thicknesses of covers and maximum
pitch of fixing bolts, studs and set screws 19
Table 12- Delivery hose connection sizes for oil classes C, D, E, F, G, H
and FAME 22
Table B.1 – Equivalent height of vent- Allowances for horizontal
pipe runs, easy and sharp bends at a filling rate of 500 lim in and at a
viscosity of 16 mm2/s 26
Table B.2- Equivalent height of vent- Allowances for horizontal pipe
runs, easy and sharp bends at a filling rate of 1000 lim in and at a
viscosity of 16 mm2/s 27
Table B.3- Equivalent height of vent- Allowances for horizontal pipe
runs, easy and sharp bends at a filling rate of 1 000 Lim in and at a
viscosity of 370 mm2/s 28
Table BA- Equivalent height of vent- Allowances for horizontal pipe
runs, easy and sharp bends at a filling rate of 1 000 Lim in and at a
viscosity of 860 mm2/s 29
Summary of pages
This document comprises a front cover, an inside front cover,
pages ito iv, pages 1 to 30, an inside back cover and a back cover.

BRITISH STANDARD BS 799-5:2010
Foreword
Publishing information
This part of BS 799 is published by BSI and came into effect on
30 April 2010. It was prepared by Technical Committee RH E/13,
Oil burning equipment. A list of organizations represented on this
committee can be obtained on request to its secretary.
Supersession
This part of BS 799 supersedes BS 799-5:1987, which is withdrawn.
Information about this document
This is a full revision of the standard, and introduces the following
principal changes.
a) The maximum capacity of primary storage tanks of types I, II
and Ill is now 4500 L.
b) Methods for leak testing and pressure testing of tanks have been
brought up to date in line with current practice.
Product certification/inspection/testing. Users of this British
Standard are advised to consider the desirability of third-party
certification/inspection/testing of product conformity with this
British Standard. Users seeking assistance in identifying appropriate
conformity assessment bodies or schemes may ask BSI to forward their
enquiries to the relevant association.
Assessed capability. Users of this British Standard are advised to
consider the desirability of quality system assessment and registration
against the appropriate standard in the BS EN ISO 9000 series by an
accredited third-party certification body.
Hazard warnings
WARNING. This British Standard calls for the use of substances
and/or procedures that can be injurious to health if adequate
precautions are not taken. It refers only to technical suitability and
does not absolve the user from legal obligations relating to health
and safety at any stage.
Presentational conventions
The provisions of this standard are presented in roman (i.e. upright)
type. Its requirements are expressed in sentences in which the principal
auxiliary verb is "shall".
Commentary, explanation and general informative material is presented
in smaller italic type, and does not constitute a normative element.
Contractual and legal considerations
This publication does not purport to include all the necessary provisions
of a contract. Users are responsible for its correct application.
Compliance with a British Standard cannot confer immunity from
legal obligations.
BS 799-5:2010 BRITISH STANDARD

This part of BS 799 specifies requirements for the construction and
testing of static carbon steel tanks for the storage of liquid fuel of
classes A2, C1, C2, D, E, F, G and H conforming to BS 2869:2006 and
FAME (fatty acid methyl esters) conforming to BS EN 14213, for use in
conjunction with oil burning equipment. The standard is applicable
to tanks of the following types intended for use above ground, either
externally or internally to a building:
a) service tanks;
b) primary storage tanks with a capacity of 90 Lor more with a
maximum height of 10m.
This standard is not applicable to tanks that are to be buried.
NOTE Steel tanks for underground storage of flammable and
non-flammable water polluting liquids are specified in 85 EN 12285·1.
In addition to the definitive requirements, this standard also requires
the items detailed in Clause 4 to be documented. For compliance with
this standard, both the definitive requirements and the documented
items have to be met.

The following referenced documents are indispensable for the
application of this document. For dated references, only the edition
cited applies. For undated references, the latest edition of the
referenced document (including any amendments) applies.
BS 21, Specification for pipe threads for tubes and fittings where
pressure-tight joints are made on the threads (metric dimensions)
BS 2869:2006, Fuel oils for agricultural, domestic and industrial
engines and boilers- Specification
85 EN 1011-1, Welding- Recommendations for welding of metallic
materials- Part 1: General guidance for arc welding
BS EN 10025-2:2004, Hot rolled products of structural steels- Part 2:
Technical delivery conditions for non-alloy structural steels
BS EN 10111:2008, Continuously hot rolled low carbon steel sheet and
strip for cold forming- Technical delivery conditions
BS EN 14213, Heating fuels- Fatty acid methyl esters (FAME)Requirements
and test methods
PD 5500, Specification for unfired fusion welded pressure vessels
Terms and definitions
For the purposes of this part of BS 799, the following terms and
definitions apply.
3.1 brimful capacity
volume of water held by a tank filled through the filling orifice to the
point of overflowing
3.2 bund
containment vessel to hold spillage from a primary tank, or tanks,
caused by leakage or overfilling

BS 799-5:2010 BRITISH STANDARD
2 • ©8512010
3.3 design pressure
pressure, or equivalent head of water, acting on the bottom, sides and
top of a tank at brimful capacity
3.4 dipstick
rigid measuring device that provides a manual method of measuring
the level of liquid in a tank
3.5 dip tape
measuring device made of tape that provides a manual method of
measuring the level of liquid in a tank
NOTE 1 A dip tape usually has a weight on the end.
NOTE 2 Dip tapes are normally used on tall vertical cylindrical tanks.
3.6 fill connection
flange or socket to which the delivery pipework is connected
3.7 gauge
device to indicate the level of liquid in a tank
3.8 gauge connection
flange or socket for the connection of a gauge
3.9 nominal capacity
<for a tank with a brimful capacity of 20000 Lor less> 95% of the
brimful capacity
3.10 nominal capacity
<for a tank with a brimful capacity of more than 20000 L> 97.5% of
the brimful capacity
3.11 outlet connection
3.12
flange or socket for the pipe that carries the contents from a tank
overfill alarm connection
flange or socket in the roof of a tank for connection of a device that
generates an audible and/or visual warning to indicate when the tank
which is being filled is reaching its permissible fill capacity
3.13 overfill prevention connection
flange or socket in the roof of a tank for connection of a device that
automatically shuts off the delivery when the nominal capacity of the
tank has been reached
3.14 return connection
flange or socket for the connection of a return pipe
3.15 service tank
tank that isolates the main storage tank or tanks from the burner
installation
3.16 sludge removal connection
flange or socket for the connection of a drain used for removal of
water and sludge from a tank
3.17 striker plate
reinforced plate welded to the bottom of a tank directly below the
dipstick or dip tape connection
3.18 tank
primary container used for the storage of liquids
BRITISH STANDARD

BS 799-5:2010 Oil Storage Tanks

BS 799-5:2010
3.19 valve
device used to control the flow of a liquid
3.20 vent connection
flange or socket in the roof of a tank for connection of a vent pipe to
prevent over-pressurization of, or vacuum in, the tank
4 Information to be supplied by the purchaser
5
5.1
The following information shall be supplied by the purchaser at the
time of enquiry and/or order:
a) the tank required, i.e. a service tank or a primary storage tank;
b) the type, size and design pressure of the tank required;
c) for type Ill and types J and K primary tanks, if transverse supports
are required (see 6.3.3 and 6.3.11);
d) for tanks 1250 mm or less in diameter, rectangular tanks 4500 L
capacity or less and vertical tanks 4.5 m or less in height, whether
manholes are required and if so how many (see Clause 7);
e) whether a tank oil heater is required and, if so, the heating
medium to be used (see 5.3, 6.4 and Clause 9);
f) for tanks of types I, II, A. B and C, if a steel cradle is required to
support the tank (see 6.15);
g) if external protection of tanks with a rust inhibiting priming paint
prior to despatch is not required (see 6.13.1);
h) if a return connection is required (see 5.5 and 6.9);
i) if an overfill alarm connection is required;
j) if an overfill prevention connection is required;
k) if an outlet pipe is to be fitted to the tank by the tank
manufacturer (see 15.1).
Service tanks
Types
Service tanks shall be of the following types.
• Type 51: cylindrical tanks having a capacity up to and including
200 L.
• Type 52: rectangular tanks having a capacity up to and including
200 L.
• Type 53: horizontal cylindrical tanks having a capacity over 200 L
but not exceeding 1 000 L.
• Type 54: rectangular tanks having a capacity over 200 L but not
exceeding 1 000 L.
• Type 55: horizontal oval tanks having a capacity not exceeding
1 000 L.

85 799-5:2010 BRITISH STANDARD
5.2 Construction and plate thickness
5.2.1 Service tanks shall be of welded construction and shall be
made of rolled steel sheets which conform to BS EN 10025-2:2004,
Grade 5275 or, for steel not exceeding 3 mm thickness, which conform
either to BS EN 10025-2:2004 Grade 5275 or to BS EN 10111:2008,
grade 0011. All welding shall be in accordance with BS EN 1011-1. For
rectangular tanks and cylindrical vertical tanks, all seams, excluding
the seams attaching the roof to the sides of the tank, shall be welded
inside and outside. The seams attaching the roof to the sides of the
tank shall be welded on the outside only.
5.2.2 For service tanks having a capacity up to and including 200 L
(types 51 and 52) the minimum thickness of the steel sheets shall be
1.6 mm.
5.2.3 For cylindrical service tanks (type 51), the maximum height shall
not exceed 750 mm and the maximum diameter shall not exceed
600mm.
5.2.4 Rectangular service tanks (type 54) shall be stayed or stiffened
and the thickness of the steel sheets shall be not less than the relevant
value given in Figure 1.
5.2.5 For cylindrical service tanks (type 53) the maximum diameter
shall be as given in Table 1 and the thickness of the shell and ends
shall be not less than the relevant values given in Table 1. For oval
service tanks (type 55) the maximum major axis of the shell shall be as
given in Table 1 and the thickness of the shell and ends shall be not
less than the relevant value given in Table 1.
Table 1 Maximum diameter or major axis and minimum thicknesses of the shell and ends for service
tanks of types 53 and 55
Capacity Minimum thickness Maximum
Shell Dished Ends dished only Flat diameter or
and Flat flanged ends unflanged major axis
flanged Flat unflanged ends
ends ends (stiffened) (not stiffened)

Up to and including 500 1.6 1.6 2.0 3.0 0.25
Over 500 up to and including 1 000 2.0 2.0 2.5 4.0 1.0

5.3 Tank oil heaters
If the provision of a tank oil heater is specified by the purchaser
[see Clause 4e)] the tank shall be fitted with a heater conforming to
Clause 9.
5.4 Sludge removal connection and outlet connection
The tank shall be fitted with a sludge removal connection and an
outlet connection as specified in Clause 11 and Clause 15, respectively.
I'

5.5 Vent connection and return connection
The tank shall be fitted with a vent connection and, if specified by the
purchaser [see Clause 4h)] . a return connection.
5.6 Manholes and inspection openings
5.7
Fitting of manholes and inspection openings shall be in accordance
with Clause 7 and Clause 8, respectively.
Pressure testing
Each tank shall be pressure tested before being painted.
When tested in accordance with Annex A, at the manufacturer's
works, or on site in the case of tanks fabricated on site, the tank shall
show no visible evidence of leakage,
The manufacturer shall provide the purchaser with a copy of the test
certificate for each tank supplied, including a statement of the design
pressure of the tank.
5.8 Marking
The following information shall be permanently and clearly marked
on the tank:
a) the number and date of this British Standard (Le, BS 799-5:2010) 1l;
b) nominal capacity (in litres);
c) manufacturer's name or trade mark;
d) manufacturer's reference number;
e) type of tank (e.g. type 51);
f) design pressure;
g) test pressure and date of testing.
6 Primary storage tanks
6.1 Types of tanks
6.1.1 Primary storage tanks shall be single skinned,
NOTE Double skinned tanks are specified in BS EN 12285-2,
6.1.2 Primary storage tanks shall be of the following types.
a) Tanks having a capacity of not more than 4 500 Land a design
pressure equivalent to a height of 0.5 m above the roof of the tank:
Type 1: horizontal cylindrical tanks;
Type II: horizontal oval tanks (with the major axis horizontal);
Type Ill: rectangular tanks.
1) Marking BS 799-5:2010 on or in relation to a product represents a
manufacturer's declaration of conformity, i.e. a claim by or on behalf of the
manufacturer that the product meets the requirements of the standard. The
accuracy of the claim is solely the claimant's responsibility. Such a declaration
is not to be confused with third-party certification of conformity.

BS 799-5:2010
BRITISH STANDARD
b) Tanks having a capacity exceeding 4500 Land not exceeding 10m
in height:
Type A: horizontal cylindrical tanks having a capacity of not
more than 60 000 L, with dished or flat ends, and a design
pressure equivalent to a height of 0.5 m above the roof of
the tank;
Type 8: horizontal cylindrical tanks having a capacity of not
more than 60000 L, with dished ends, and a design pressure
equivalent to a height of 4.5 m above the roof of the tank;
Type C: horizontal cylindrical tanks having a capacity of not
more than 60000 L, with dished ends, and a design pressure
equivalent to a height of more than 4.5 m above the roof of
the tank;
Type D: vertical cylindrical tanks having a capacity of not
more than 65 000 L, with dished ends, and a design pressure
equivalent to a height of 0.5 m above the roof of the tank;
Type E: vertical cylindrical tanks having a capacity of not
more than 145 000 L, with dished ends, and a design pressure
equivalent to a height of 7.5 m above the roof of the tank;
Type F: vertical cylindrical tanks having a capacity of not
more than 65 000 L, with dished ends, and a design pressure
equivalent to a height of more than 7.5 m above the roof of
the tank;
Type G: vertical cylindrical tanks having a capacity of not
more than 145000 L, with flat bottom end plates, and a
design pressure equivalent to a height of 0.5 m above the
roof of the tank;
Type J: rectangular tanks having a capacity of not more
than 150 000 L, and a design pressure equivalent to a height
of 0.5 m above the roof of the tank;
Type K: rectangular tanks having a capacity of not more
than 150000 L, and a design pressure equivalent to a height
of 7.5 m above the roof of the tank.
6.2 Construction
6.2.1 Types I, II and Ill
6.2.2
Primary storage tanks of types I, II and Ill shall be of welded
construction and made of rolled carbon steel sheets or plates
conforming to 85 EN 10111:2008, grade D11. Galvanized steel shall
not be used. All welding shall be in accordance with 85 EN 1011-1.
Types A to K
Primary storage tanks of types A to K shall be of welded
construction and made of rolled carbon steel plates conforming to
85 EN 10025-2:2004, grade 5275. Galvanized steel shall not be used.
All welding shall be in accordance with 85 EN 1011-1.
BRITISH STANDARD
(
BS 799-5:2010
6.3 Dimensions, plate thickness and welding
6.3.1 Type I
For type I tanks the maximum diameter of the shell and the minimum
plate thickness of the shell and ends shall be as given in Table 2.
6.3.2 Type II
For type II tanks the minimum plate thickness of the shell and ends
shall be as given in Table 2.
o-;, Table 2 Maximum diameter and minimum plate thicknesses of the shell and ends of primary storage
('
tanks of types I and II
Capacity Minimum thickness of plate Maximum
Shell Dished Ends dished only Flat diameter
and Flatflanged ends unflanged for tanks
flanged Flat unflanged ends of type I
ends ends (stiffened) (not
stiffened)
L mm mm mm mm m
Up to and including 500 1.6 1.6 2.0 4.0 0.75
Over 500 up to and including 1400 2.0 2.0 2.5 4.0 1.0
Over 1400 up to and including 2 300 2.5 2.5 4.0 5.0 1.2
Over 2300 up to and including 4500 4.0 4.0 5.0 8.0 1.4
6.3.3 Type Ill
For type Ill tanks the thickness of the sheet and the pitch of the
staying or stiffening shall be as shown in Figure 1.
The internal stays or stiffening shall be arranged to allow complete
draining. If specified by the purchaser [see Clause 4c)] the tank shall
be fitted with two or more transverse supports spaced at intervals not
less than as shown in Figure 2.

BS 799-5:2010 BRITISH STANDARD
Figure 1 Relationship between design pressure, pitch of stays or stiffening and plate thickness for
rectangular service tanks of type 54 and rectangular primary storage tanks of types Ill, J and K

P Pitch of stays or stiffening, in millimetres (mm}
T Plate thickness, in millimetres (mm)
H Total equivalent design head, measured from the base of the tank, in metres of water
P= 190T/–JH
BRITISH STANDARD BS 799-5:2010
Figure 2 Relationship between design pressure, span between supports and plate thickness for
rectangular primary storage tanks of types Ill, J and K

Key A
A Maximum span between supports, in millimetres (mm)
T Plate thickness, in millimetres (mm)
H Total equivalent design head, measured from the base of the tank, in metres of water
A =225TI~H

BS 799-5:2010 BRITISH STANDARD
6.3.4 Type A
For type A tanks, dished and flanged end plates shall be concave to
the oil pressure and shall have dimensions as shown in Figure 3.
The thickness of the shell and end plates shall be not less than the
values given in Table 3.
Where the end plates are made of more than one plate, the butt
joints shall be fully welded from both sides of the plate.
All seams shall be fully welded inside and outside.
Figure 3 Shallow dished and flanged end

Table 3 Minimum plate thicknesses for primary storage tanks of type A
Internal diameter Thickness
Shell Dished ends Flat ends (unstiffened)
m mm mm mm
Up to and including 1 4.0 4.0 5.0
Over 1 up to and including 1.6 5.0 5.0 8.0
Over 1.6 up to and including 2.4 6.0 6.0 Dished ends only
Over 2.4 up to and including 2.7 8.0 6.0 Dished ends only
6.3.5 Type B

For type B tanks, end plates shall be dished and flanged, and butt
welded or lap welded to the shell. The ends shall be concave to the oil
pressure and shall have dimensions as shown in Figure 3.
The thickness of the shell and end plates shall be not less than the
values given in Table 4.
Where the end plates are made of more than one plate, the butt joints
shall be fully welded from both sides of the plate.
All seams shall be fully welded inside and outside.

BS 799-5:2010 OIl Storage tanks
6.3.6 Type C
For type C tanks, end plates shall be dished and flanged and butt
welded or lap welded to the shell. The ends shall be concave to the oil
pressure and shall have dimensions as shown in Figure 4.
The construction shall be as specified in PD 5500 and the plate
thickness shall be not less than the values given in Table 4.
Where the end plates are made of more than one plate, the butt
joints shall be fully welded from both sides of the plate.
All seams shall be fully welded inside and outside.
Figure 4 Dished and flanged end
Nominal proportions
Ri:::::: 1.0D0
ri:::: 0.0600
D,
Table 4 Minimum plate thicknesses for primary storage tanks of types Band C
Internal diameter Thickness
Shell Dished ends
m mm mm
Up to and including 1 4.0 4.0
Over 1 up to and including 1.6 5.0 5.0
Over 1.6 up to and including 2.4 6.0 10.0
Over 2.4 up to and including 2.7 8.0 10.0
6.3.7 TypeD
For type D tanks, end plates shall be dished and flanged and butt
welded or lap welded to the shell.
The dished ends shall be concave to the oil pressure. The top ends
shall have dimensions as shown in Figure 3. The bottom ends shall
have dimensions as shown in Figure 4.
The thickness of the shell and end plates shall be not less than the
values given in Table 5.

BS 799-5:2010 BRITISH STANDARD
Where the end plates are made of more than one plate, the butt
joints shall be fully welded from both sides of the plate. All seams,
excluding the seams attaching the roof to the sides of the tank, shall
be fully welded inside and outside. The seams attaching the roof to
the sides of the tank shall be fully welded on the outside only.
Table 5 Minimum plate thicknesses for primary storage tanks of type D
Up to and including
Over
Up to and including
Over
Up to and including

Tank size Thickness
Diameter Depth Shell and top Bottom dished
m
1.0
1.0
1.6
1.6
2.7
dished end end
m mm mm
or 2.0 4.0 4.0
or 2.0 5.0 5.0
or 6.5
or 6.5 6.0 6.0
or 10.0
The tank shall be fitted with a cylindrical skirt or supporting brackets,
to support the tank such that the centre of the end plate will be at
least 300 mm clear of the ground when the tank is installed. If the
tank has a skirt, inspection openings conforming to Clause 8 shall be
fitted in the skirt.
6.3.8 Type E
For type E tanks, end plates shall be dished and flanged, and butt
welded or lap welded to the shell.
The dished ends shall be concave to the oil pressure. The top ends
shall have dimensions as shown in Figure 3 for tanks up to 2 700 mm
diameter and as shown in Figure 4 for tanks with larger diameters .
The bottom ends shall have dimensions as shown in Figure 4.
The thicknesses of the shell and end plates shall be not less than the
values given in Table 6.
Where the end plates are made of more than one plate, the butt
joints shall be fully welded from both sides of the plate. All seams,
excluding the seams attaching the roof to the sides of the tank, shall
be fully welded inside and outside. The seams attaching the roof to
the sides of the tank shall be fully welded on the outside only.
The tank shall be fitted with a cylindrical skirt or supporting brackets,
to support the tank such that the centre of the end plate will be at
least 300 mm clear of the ground when the tank is installed. If the
tank has a skirt, inspection openings conforming to Clause 8 shall be
fitted in the skirt.

BRITISH STANDARD BS 799-5:2010
6.3.9 Type F
For type F tanks, end plates shall be dished and flanged and butt
welded or lap welded to the shell.
The dished ends shall be concave to the oil pressure and shall have
dimensions as shown in Figure 4.
The construction shall be as specified in PD 5500 and the plate
thickness shall be not less than the values given in Table 6.
Where the end plates are made of more than one plate, the butt
joints shall be fully welded from both sides of the plate. All seams,
excluding the seams attaching the roof to the sides of the tank, shall
be fully welded inside and outside. The seams attaching the roof to
the sides of the tank shall be fully welded on the outside only.
The tank shall be fitted with a cylindrical skirt or supporting brackets,
to support the tank such that the centre of the end plate will be at
least 300 mm clear of the ground when the tank is installed. If the
tank has a skirt, inspection openings conforming to Clause 8 shall be
fitted in the skirt.
Table 6 Minimum plate thicknesses for primary storage tanks of types E and F
Up to and including
Over
Up to and including
Over
Up to and including
Over
Up to and including
Over
Up to and including
Tank size Thickness
Diameter Depth Shell Top dished end Bottom dished end
(see Figure 4)
m m mm mm mm
1.0 or 2.0 4.0 4.0 (see Figure 3) 4.0
1.0 or 2.0 5.0 5.0 (see Figure 3) 5.0
1.5 or 6.0
1.5 or 6.0 5.0 6.0 (see Figure 3) 6.0
1.8 or 6.5
1.8 or 6.5 6.0 8.0 (see Figure 3) 10.0
2.7 or 10.0
2.7 or 10.0 6.0 10.0 (see Figure 4) 10.0
4.0 or 10.0
6.3.10 Type G
For type G tanks, the top end plates shall be dished and flanged and
butt welded or lap welded to the shell. The top dished ends shall
be concave to the oil pressure and shall have dimensions as shown
in Figure 3 up for tanks up to 2 700 mm diameter and as shown in
Figure 4 for tanks of larger diameters.
The thicknesses of the shell and end plates shall be not less than the
values given in Table 7.
Where the end plates are made of more than one plate, the butt
joints shall be fully welded from both sides of the plate. All seams,
excluding the seams attaching the roof to the sides of the tank, shall
be fully welded inside and outside. The seams attaching the roof to
the sides of the tank shall be fully welded on the outside only.

BS 799-5:2010 BRITISH STANDARD
Table 7 Minimum plate thicknesses for primary storage tanks of type G
Up to and including
Over
Up to and including
Over
Up to and including
Tank size Thickness
Diameter Depth Shell and top Bottom flat end
dished end
m m mm mm
1.0 or 2.0 4.0 (see Figure 3) 5.0
1.0 or 2.0 5.0 (see Figure 3) 6.0
2.0 or 7.5
2.0 or 7.5 6.0 (see Figure 4) 8.0
4.0 or 10.0
6.3.11 Types J and K
For tanks of types J and K, where the plates are made up from more
than one piece of steel, the butt joints shall be fully welded from both
sides of the plate.
All seams, excluding the seams attaching the roof to the sides of the
tank, shall be fully welded inside and outside. The seams attaching the
roof to the sides of the tank shall be fully welded on the outside only.
The flat plates shall be stayed or stiffened by one of the following means:
a) stayed with the thickness of the plates and the pitch of the stays
as shown in Figure 1;
b) stiffened by carbon steel sections fitted inside and/or outside
the tank;
c) both stayed and stiffened by carbon steel sections fitted inside
and/or outside the tank.
The stays and/or stiffeners shall be so arranged that they do not:
1) restrict drainage or access to any part of the internal surfaces; or
2) restrict access to and operation of oil level indicators, oil heaters,
thermostats, etc.
If specified by the purchaser [see Clause 4c)] the tank shall be fitted
with two or more transverse supports spaced at intervals not less than
as shown in Figure 2.
6.4 Tank oil heaters
If the provision of a tank oil heater is specified by the purchaser
[see Clause 4e)] the tank shall be fitted with a heater conforming to
Clause 9.
NOTE Where a heater is fitted, emergency relief venting of the tank is
recommended.
6.5 Gauge connection
The tank shall be fitted with a gauge connection.

BRITISH STANDARD BS 799-5:2010
6.6 Sludge removal connection and outlet connection
The tank shall be fitted with a sludge removal connection and an
outlet connection as specified in Clause 11 and Clause 15, respectively.
6.7 Fill connection
6.8
The tank shall be fitted with a filling pipe connection conforming to
Clause 12,
Vent connection
The tank shall be provided with a vent pipe connection conforming to
Clause 13,
6.9 Return connection
If specified by the purchaser [see Clause 4h)] the tank shall be fitted
with a return connection.
6.10 Outlet connections and pipes
6.11
Outlet connections and pipes shall be fitted to the tank as specified in
Clause 15.
Manholes and inspection openings
The fitting of manholes and inspection openings shall be in accordance
with Clause 7 and Clause 8, respectively,
6.12 Pressure testing
Each tank shall be pressure tested before being painted.
When tested in accordance with Annex A, at the manufacturer's
works, or on site in the case of tanks fabricated on site, the tank shall
show no visible evidence of leakage.
The manufacturer shall provide the purchaser with a copy of the test
certificate for each tank supplied including a statement of the design
pressure of the tank.
6.13 Cleaning and painting
6.13.1 Types I, II and Ill
Each tank fabricated at the manufacturer's works shall be cleaned
externally before despatch and, unless otherwise specified by
the purchaser [see Clause 4g)] , shall be painted externally with a
rust-inhibiting priming paint.
The inside of the tank shall be cleaned and all openings closed to
prevent ingress of foreign matter,
Tanks built on site shall be cleaned externally and internally after
pressure testing (see 6.12) and painted externally with a rust-inhibiting
priming paint.
BS 799-5:2010 BRITISH STANDARD

6.13.2 Types A to K
6.14
Tanks of types A to K fabricated at the manufacturer's works shall,
before despatch, be cleaned externally and painted with a rust-inhibiting
priming paint; the inside of the tank shall be cleaned and all openings
closed to prevent ingress of foreign matter. Tanks fabricated on site shall
be cleaned externally and internally after pressure testing (see 6.12) and
painted externally with a rust-inhibiting priming paint.
Marking
The following information shall be permanently and clearly marked
on the tank:
a) the number and date of this British Standard (i.e. BS 799-5:2010 2l);
b) type of tank (e.g. Type II);
c) capacity (in litres);
d) date of manufacture;
e) manufacturer's name or trade mark;
f) manufacturer's reference number;
g) design pressure;
h) test pressure and date of testing.
6.15 Steel cradles for types I, II, A, Band C tanks
6.15.1 General
6.15.2
If specified by the purchaser [see Clause 4t)] the tank manufacturer
shall supply steel cradles conforming to 6.15.2 or 6.15.3, as applicable,
such that the tank can be supported at a slope of 1 in 50 in the
direction of the sludge removal connection.
Cradles for types I and II
The steel cradles shall have the dimensions given in Table 8 or Table 9,
as applicable. If the cradles are welded to the tank by the tank
manufacturer they shall be positioned as shown in Figure 5 or Figure 6,
as applicable. If the cradles are supplied loose with the tank, the tank
manufacturer shall supply a copy of Figure 5 or Figure 6 to the purchaser
with the tank together with instructions to position the tank on the
cradles as shown in the figure and to put a waterproof membrane to
completely fill the space between the tank and each cradle.
2l Marking 85 799-5:2010 on or in relation to a product represents a
manufacturer's declaration of conformity, i.e. a claim by or on behalf of the
manufacturer that the product meets the requirements of the standard. The
accuracy of the claim is solely the claimant's responsibility. Such a declaration
is not to be confused with third party certification of conformity.

BRITISH STANDARD 85 799-5:2010
Table 8 Dimensions of steel cradles for tanks of type I (see Figure 5)
Tank diameter, D Minimum width of Minimum length of
cradles, 8 cradles, C
m mm m
0.75 65 0.66
1.0 75 0.90
1.2 100 1.05
1.4 100 1.25
Figure 5 Positions of steel cradles for primary storage tanks of type I
Linear dimensions in millimetres

Table 9 Dimensions of steel cradles for tanks of type II (see Figure 6)
Tank capacity
L
Up to and including 1 300
Over 1300 up to and including 4500
Minimum width of cradles, 8
mm
BS 799-5:2010 BRITISH STANDARD
6.15.3 Cradles for types A, B and C
The steel cradles shall have the dimensions given in Table 10. If the
cradles are welded to the tank by the tank manufacturer they shall be
positioned as shown in Figure 7. If the cradles are supplied loose with
the tank, the tank manufacturer shall supply a copy of Figure 7 to the
purchaser with the tank together with instructions to position the tank
on the cradles as shown in the figure and to put a waterproof membrane
to completely fill the space between the tank and each cradle.
Table 10 Dimensions of steel cradles for tanks oftypes A, Band C (see Figure 7)
Tank length of Minimum Minimum
diameter, D shell, A width of length of
cradles, 8 cradles, C

Figure 7 Positions of cradles for primary storage tanks of types A, Band C
D
Linear dimensions in millimetres

BS 799-5:2010
7 Manholes
All cylindrical tanks over 1250 mm diameter and all rectangular tanks
over 4 500 L capacity shall be fitted with a manhole.
Vertical tanks over 4,5 min height shall have either an additional
manhole near the bottom of the vertical shell or an internal ladder.
Other tanks shall be fitted with a manhole if specified by the purchaser
[see Clause 4d)]
Manholes shall be not less than 600 mm in diameter if circular in shape
and not less than 650 mm long and 600 mm wide if oval in shape; the
600 mm dimension shall be parallel to the longitudinal axis of the
tank. Manholes of other shapes shall have no access dimension of less
than 600 mm.
Manholes shall be stiffened by the provision of a flanged neck ring
welded around the opening or alternatively in the case of a rectangular
tank by a flat faced compensating ring welded around the opening.
Holes for studs and set screws shall not penetrate the tank plate.
Where practicable, manholes shall be located on top of the tank. Each
manhole shall be provided with a cover securely fixed by bolts, studs
or set screws and shall have a liquid- and vapour-tight joint made with
a gasket of oil-resistant material. The maximum pitch of fixing bolts,
studs or set screws in manholes for tanks of types A, B, D, E, G, J and K
shall be as given in Table 11.
The minimum thickness for covers for manholes shall be not less than
the thickness of the body plate for service tanks and for primary
storage tanks of types I, II and Ill and shall be as given in Table 11 for
tanks of types A, B, D, E, G, J and K.
The plate thickness and fixing details of manholes for tanks of type C
and type F shall be as specified in PD 5500.
NOTE The thicknesses specified in Table 11 have been adopted to provide
for a minimum number of fixing bolts, studs or set screws and to enable
top and bottom manhole covers on vertical tanks to be interchangeable.
Table 11 Manholes- Minimum thicknesses of covers and maximum pitch of
fixing bolts, studs and set screws
Type of tank
A, J
B,D,G,K
E
Cover thickness
mm
10
10
12
8 Inspection openings
Maximum pitch of M16 bolts,
studs or set screws
mm
100
80
90
Inspection openings shall be not less than 125 mm in diameter if
circular in shape and not less than 125 mm x 125 mm if square and,
if below the brimful capacity level of the tank, shall be sealed as
specified in Clause 7.

BS 799-5:2010 BRITISH STANDARD
9 Tank oil heaters
COMMENTARY ON CLAUSE 9
The means of heating may be electricity, steam or hot water.
Heaters can be of the following types:
a) immersion type, inserted through the outlet end of the tank;
b) submersion type, inserted through the top of the tank;
c) outflow type, where the heating elements are concentrated around
the outlet from the tank;
d) trace heating;
(f) e) recirculation.
 9.1 Tank insulation

Any tank fitted with a heater shall be insulated.
9.2 Electric heaters
2::.1 The electric loading of heaters installed in tanks for the storage of .. oil of classes C and D shall not exceed 1.6 W/cm2 of element sheath
surface and for oil of classes E, F, G or H shall not exceed 1.24 W/cm2 of
() element sheath surface. The surface temperature of the sheath shall
r.,; be thermostatically controlled so as to not exceed 175 oc. In addition
~:~ a safety cut-out shall be provided. Heating elements and thermostats
shall be of the dry type so that they can be withdrawn without
emptying the tank.
NOTE The element sheath or pocket should be supported as necessary
T' along its length by cradles or other supports. -.··· • Heaters fitted to tanks which are to be placed in the open air shall be
provided with weatherproof terminal covers.
F Electric heaters shall be independently earthed.
9.3 Steam and hot water heaters or coils (including high
-·– pressure hot water heaters) ~- :_;
c Heaters or coils shall be constructed of seamless steel tube either:
a) without joints within the tank; or
b) where unavoidable, with joints within the tank.
Where such joints are unavoidable they shall be fully welded in
(._' accordance with BS EN 1011-1. ..
-· Heaters shall be supported at intervals along their length by cradles or
other supports.
Steam heaters shall be arranged to drain freely so that they are not
subject to water hammer.
9.4 Location
All heaters and controlling thermostats shall be so located in relation
to the draw-off level that their surfaces do not become exposed (see
Clause 15).
The tank shall be fitted with visual and audible alarms to give warning
when the oil level falls below a depth of 300 mm above the heater.
BRITISH STANDARD

BS 799-5:2010
10 Oil level indicators
The tank manufacturer shall supply an oil level indicator of one of the
following types:
a) a dipstick or dip tape;
b) a float gauge;
c) a hydrostatic gauge;
d) an electronic gauge;
e) a displacement gauge;
f) a sight tube.
NOTE The main purpose of an oil/eve/ indicator is to show the
approximate contents of the tank.
If a dipstick or dip tape is supplied the tank shall be fitted with a
striker plate.
11 Sludge removal connection
The tank manufacturer shall fit the tank with a sludge removal
connection.
12 filling pipe and delivery hose connections
12.1 Filling pipe connection
12.2
The tank shall be fitted with a filling pipe connection.
If the filling pipe connection is at the bottom of the tank it shall be
fitted with a non-return valve.
If the filling pipe connection is continued below the surface of the
oil and could form a siphon, an anti-siphoning device, such as a 5 mm
hole drilled in the drop pipe from the connection, shall be provided
above the maximum oil level within the tank.
Delivery hose connections for road tanker deliveries
Tanks to be filled from a road tanker shall be fitted with a delivery
hose connection which shall have a parallel male thread conforming
to BS 21. The dimensions of the delivery hose connection shall be not
less than the value given in Table 12.
The connecting parallel thread shall be protected by means of a
removable non-ferrous screw-on cap which shall be secured to the
delivery hose connection by a chain.
Where the delivery hose connection terminates below the brimful
capacity of the tank an oil-tight valve shall be fitted to the end of the
delivery hose connection.
NOTE The height of the delivery hose connection should be no more
than 1.2 m above the base of the tank.
12.3 Delivery hose connections for rail tanker deliveries
Tanks to be filled from a rail tanker shall be fitted with a dry
break coupling.
BS 799-5:2010 BRITISH STANDARD
Table 12 Delivery hose connection sizes for oil classes C, D, E, F, G, Hand FAME
Oil Total length of Minimum bore (nominal) of Delivery hose connection,
delivery hose A) delivery hose A) male pipe thread
conforming to BS 21
m mm mm
Classes C, D and FAME up to 12 32 for tanks up to and including so
1 500 L capacity
50 for tanks over 1 500 L capacity 50
over 12 50 for tanks up to and including 50
1 500 L capacity
65 for tanks over 1 500 L capacity 65
Class E up to 12 65 80
over 12 80 80
Classes F, G and H – 80 so
c. A) As speC.if .ie d by the spec.if .ie r ofthe tank .
13 Vent pipe connection
For tanks over 200 L capacity, the bore of the vent pipe connection
shall be not less than 50 mm nominal diameter and at least equal to
the bore of the filling pipe connection or outlet connection whichever
is the greater, or the sum of the bores of all the filling or outlet pipe
connections if there is more than one.
14 Vent pipe
If a vent pipe is fitted by the tank manufacturer, the open end of the
vent pipe shall be turned down and fitted with an open mesh wire
cage. Gauze shall not be used.
If a vent pipe is fitted by the tank manufacturer, it shall be so arranged
so that any fuel discharge is directed into the bun d.
NOTE 1 Vent pipe design should be in accordance with the design pressure
of the tank [see Clause 4b)] .
(; NOTE 2 The relationship between the layout of the vent pipe and the
design pressure of the tank can be calculated using the method given in
Annex B together with Figures 1 and 2.

15 Outlet connections and pipes
15.1 General
The tank manufacturer shall fit an outlet connection to the tank.
This shall be a bottom outlet connection conforming to 15.2 or
a top outlet connection conforming to 15.3. If specified by the
purchaser [see Clause 4k)] an outlet pipe shall be fitted to the tank
by the tank manufacturer.

BRITISH STANDARD BS 799-5:2010
15.2 Bottom outlet connections
For all oils except classes C and D, the outlet connection shall be
so arranged as to leave a minimum of 50 mm of dead space in the
bottom of the tank. In the case of a tank fitted with a heater, the
outlet connection shall be fitted a minimum of 150 mm above the top
of the heater.
If an outlet pipe is fitted to the tank, a valve shall be provided on the
outlet pipe as close to the tank as possible.
15.3 Top outlet connections
Top outlets connections shall comprise an internal suction pipe which
shall terminate 50 mm above the tank base.

BS 799-5:2010 BRITISH STANDARD
Annex A (normative) Methods for pressure testing of service
tanks and primary storage tanks
WARNING. During pressure testing there is a risk that the tank might
rupture. It is essential to take precautions to ensure that personnel
are protected against injury should rupture of the tank occur.
A.1 Tanks other than types D toG
A.1.1 General
A.1.2
The tank shall be subjected either to a leak test in accordance with A.1.2
followed by a design pressure test in accordance with A.1.3, or to a
hydraulic test in accordance with A.1.4, using a total head of water, or an
equivalent pressure, equal to the required design pressure of the tank.
Leak test
All but two of the tank connections shall be blanked off. An air line
shall be fitted to one connection and a pressure release valve and a
pressure gauge or water tube shall be connected to the remaining
connection. The pressure release valve shall be set to release at the
test pressure (see A.1.1). The pressure shall be raised gradually until
a pressure of 0.2 bar is reached. All welds shall be checked for leaks
using a soap solution. If leaks are detected the air pressure shall be
released, the leaks re-welded and the test repeated.
A.1.3 Design pressure test
All but two of the tank connections shall be blanked off. An air line
shall be fitted to one connection and a pressure release valve and a
pressure gauge or water tube shall be connected to the remaining
connection. The pressure release valve shall be set to release at the
test pressure (see A.1.1). The pressure shall be raised gradually until
the test pressure is reached and held for 60s. If there is no loss of
pressure the tank shall be deemed to have passed the test.
A.1.4 Hydraulic tests
Test 1
All but one of the top connections on the tank shall be blanked off and
a header pipe of a length which will apply the test pressure (see A.1.1)
when it is full of water shall be connected to the remaining connection.
The tank shall be filled with water until the header pipe is full to
overflowing. The water level shall be held for 60s. If the tank leaks, as
indicated by a drop in the water level. the tank shall be emptied the
leaks re-welded and the test repeated. After the test the tank shall be
emptied and thoroughly dried.
Test 2
All the openings on the tank except one shall be blanked off. The
tank shall be filled with water to brimful capacity. On the remaining
/ ·,
BRITISH STANDARD
A.2
85 799-5:2010
opening a water pressure pump fitted with a pressure gauge shall be
fitted. Additional water shall be applied with the pump until the test
pressure is reached (see A.1.1) and held for 60s. If there is no loss of
pressure the tank shall be deemed to have passed the test. If the tank
leaks, as indicated by a drop in the pressure, the tank shall be emptied
the leaks re-welded and the test repeated. After the test the tank
shall be emptied and thoroughly dried.
Tanks of types D toG
Vertical storage tanks of types D to G shall either be tested vertically
in accordance with A.1 or alternatively shall be tested horizontally
in accordance with A.1 but at a pressure above the design pressure
equivalent to a head of water not less than 0.7 m above the height of
the tank.
NOTE The testing of vertical storage tanks of types D toG horizontally
should be subject to agreement between the purchaser and the
manufacturer. When testing flat bottom vertical tanks horizontally the
flat bottoms should be suitably stiffened for the test.
Annex B (informative) Avoidance of overfilling of oil storage tanks
When an oil storage tank is overfilled to the extent that oil flows from
the vent pipe (or unloading device), the friction of the oil passing
through the pipe causes a pressure to be set up in the tank in addition
to that due to the head of oil in the vent pipe. If the vent pipe is too
small in diameter or too long, the total pressure due to friction plus the
static head may be sufficient to cause serious damage to the tank. The
pressure developed at the top of the tank depends upon the height,
the bore, the total length and the number of bends in the vent pipe,
the viscosity of the oil and the filling rate.
As shown in the examples in this annex, the pressure at the top of the
tank due to overfilling can be determined from Figures 8.1 to 8.4 used
in conjunction with Tables 8.1 to 8.4, respectively, for different values
of viscosity and filling rate.
Having determined the pressure at the top of the storage tank, it may
be necessary for the specifier of the tank to revise one or more of the
following to avoid overfilling of the tank:
a) the type of tank(s) to be used, i.e. cylindrical or rectangular;
b) the design pressure of the tank(s);
c) the vent pipe diameter and length, and unloading device (if any);
d) the location of the tank(s) and the layout of the tank installation.
If changes are decided upon, further reference to the appropriate
figure and table should be made to determine the oil pressure that
would result.
The pressure developed varies for different classes of oil. Where E, F, G
or H grades of fuel oil are to be used, it is better to design the storage
installation to suit the maximum viscosity fuel oil available that is
suitable for the oil-burning equipment.

BS 799-5:2010 BRITISH STANDARD
EXAMPLE 1
Calculation of the total head developed for a 50 mm bore vent pipe
of 7.5 m vertical height, 7.5 m horizontal run and four easy bends.
Total equivalent vent height calculated using Table 8.1:
Vertical height: = 7.5m
(including entry, exit, return bend)
Horizontal run of 7.5 m: = 2.6m
(taken pro rata from Table 8.1)
Four easy bends: = 1.2 m
Total equivalent vent height: = 11.3 m
From Figure 8.1, a vent of 11.3 m height and 50 mm bore would result
in a head of 17.5 m of water at the top of the tank.
Table 8.1 Equivalent height of vent- Allowances for horizontal pipe runs,
easy and sharp bends at a filling rate of 500 L/min and at a viscosity
of 16 mm2/s
Fitting Bore of vent
SOmm 65mm SOmm
Equivalent height of vent
m
10 m of horizontal run 3.5 1.5 0.5
Each easy bend 0.3 0.15 0.08
Each sharp bend 0.6 0.3 0.15
Figure 8.1 Graph showing pressure developed when a tank is overfilled with oil of classes CorD at a
filling rate of 500 L!min and at a viscosity of 16 mm2/sAl (relative density 0.84)

X Height of vent
above top of tank,
in metres (m)
Y Head developed
at top of tank, in
metres of water
Solid lines: Pressure at
top of tank with the
vent overflowing
Dashed line: Static
X pressure only
NOTE Pressures given include: (static head due to vertical column of oil)+ (entry and exit losses)+ (friction
loss in pipe)+ (friction loss in return bend at top of vent).
AI 1 mm2/s=1c5t.

BRITISH STANDARD BS 799-5:2010
EXAMPLE2
Calculation of the total head developed for a 65 mm bore vent pipe
of 7.5 m vertical height, 7.5 m horizontal run and four easy bends.
Total equivalent vent height calculated using Table 8.2:
Vertical height: = 7.5 m
(including entry, exit, return bend)
Horizontal run of 7.5 m = 2.6m
(calculated pro rata from Table 8.2)
Four easy bends = 2.0m
Total equivalent vent height = 12.1 m
From Figure 8.2 a vent of 12.1 m height and 65 mm bore would result
in a head of 19.2 m of water at the top of the tank.
Table 8.2 Equivalent height of vent- Allowances for horizontal pipe runs,
easy and sharp bends at a filling rate of 1 000 Lim in and at a viscosity
of 16 mm2/s
Fitting Bore of vent
50mm 65mm SOmm
Equivalent height of vent
m
10m of horizontal run 6.5 3.5 2.0
Each easy bend 0.7 0.5 0.25
Each sharp bend 1.4 0.9 0.5
Figure 8.2 Graph showing pressure developed when a tank is overfilled with oil of classes CorD at a
filling rate of 1 000 Lim in and at a viscosity of 16 mm2/s (relative density 0.84)

Key
X Height of vent
above top of tank,
in metres (m)
Y Head developed
at top of tank, in
metres of water
Solid lines: Pressure at
top of tank with the
25 vent overflowing
Dashed line: Static
X pressure only
NOTE Pressures given include: (static head due to vertical column of oil)+ (entry and exit losses)+ (friction
loss in pipe)+ (friction loss in return bend at top of vent).

BS 799-5:2010 BRITISH STANDARD
EXAMPLE3
Calculation of the total head developed for an 80 mm bore vent pipe
of 7.5 m vertical height, 7.5 m horizontal run and four easy bends.
Total equivalent vent height calculated using Table 8.3:
Vertical height: = 7.5 m
(including entry, exit, return bend)
Horizontal run of 7.5 m = 3.0m
(calculated pro rata from Table 8.3)
Four easy bends = O.Sm
Total equivalent vent height = 11.3 m
From Figure 8.3 a vent of 11.3 m height and 80 mm bore would result
in a head of 19.2 m of water at the top of the tank.
Table 8.3 Equivalent height of vent- Allowances for horizontal pipe runs,
easy and sharp bends at a filling rate of 1 000 lim in and at a viscosity
of 370 mm2/s
Fitting Bore of vent
65mm 80mm 100mm
Equivalent height of vent
m
10 m of horizontal run 6.0 4.0 2.0
Each easy bend 0.3 0.2 0.1
Each sharp bend 0.6 0.4 0.2
Figure 8.3 Graph showing pressure developed when a tank is overfilled with oil of classes E, For Gat a
filling rate of 1000 L/min and at a viscosity of 370 mm2/s (relative density 0.935)

Key
X Height of vent
above top of tank,
in metres (m)
Y Head developed
at top of tank, in
metres of water
Solid lines: Pressure at
top of tank with the
vent overflowing
Dashed line: Static
X pressure only
NOTE Pressures given include: (static head due to vertical column of oil) +(entry and exit losses)+ (friction
loss in pipe)+ (friction loss in return bend at top of vent).

BRITISH STANDARD BS 799-5:2010
EXAMPLE4
Calculation of the total head developed for an 80 mm bore vent pipe
of 7.5 m vertical height, 7.5 m horizontal run and four easy bends.
Total equivalent vent height calculated using Table 8.4:
Vertical height = 7.5 m
(including entry, exit, return bend)
Horizontal run of 7.5 m = 4.5 m
calculated pro rata from Table 8.4
Four easy bends = 0.4 m
Total equivalent vent height = 12.4m
From Figure 8.4 a vent of 12.4 m height and 80 mm bore would result
in a head of 30m of water at the top of the tank.
Table 8.4 Equivalent height of vent- Allowances for horizontal pipe runs,
easy and sharp bends at a filling rate of 1 000 lim in and at a viscosity
of 860 mm2/s
Fitting Bore of vent ·
65mm 80mm 100mm
Equivalent height of vent
m
10 m of horizontal run 8.0 6.0 4.0
Each easy bend 0.15 0.1 0.07
Each sharp bend 0.3 0.2 0.14
Figure 8.4 Graph showing pressure developed when a tank is overfilled with oil of classes E, For Gat a
filling rate of 1 000 llmin and at a viscosity of 860 mm2/s (relative density 0.946)

Key
X Height of vent
above top of tank,
in metres (m)
Y Head developed
at top of tank, in
metres of water
Solid lines: Pressure at
top of tank with the
25 vent overflowing
Dashed line: Static
X pressure only
NOTE Pressures given include: (static head due to vertical column of oil)+ (entry and exit losses)+ (friction
loss in pipe)+ (friction loss in return bend at top of vent).

85 EN 12285-1, Workshop fabricated steel tanks- Part 1: Horizontal
cylindrical single skin and double skin tanks for the underground
storage of flammable and non-flammable water polluting liquids
85 EN 12285-2, Workshop fabricated steel tanks- Part 2: Horizontal
cylindrical single skin and double skin tanks for the aboveground
storage of flammable and non-flammable water polluting liquids
85 EN ISO 9000 (Series), Quality management systems