BS 799-5:1987 download.Oil burning equipment Part 5 : Specification for oil storage tanks.
1 Scope
This Part of BS 799 specifies requirements for tanks for the storage of liquid fuel, used in conjunction with oil burning equipment, and includes:
a) integral tanks which form a part of a complete
oil fired unit;
b) service tanks;
c) storage tanks with a maximum height of 10 m.
The maximum capacities of the various types of tank are specified.
BS 799-5 is applicable to tanks constructed of plain carbon steel.
NOTE I The requirements of BS 799-5 should not be applied to tanks constructed of plastics or materials other than plain carbon steel.
NOTE 2 The titles of the publications referred to in BS 799-5 are listed on the inside back cover.
2 Definitions
For the purposes of this Part of BS 799. the following definitions apply.
2.1
oil
petroleum oil fuels of classes C, D, E, F, G and H as specified in BS 2869
2.2
integral tank
a small tank up to 25 L capacity which forms an integral part of an oil fired unit or appliance and which requires filling by hand
2.3
service tank
an auxiliary tank having a capacity of not more than 1 000 L, which isolates the main storage tank or tanks from the burner installation
2.4
design pressure or head
that pressure or equivalent head of water acting at the bottom, sides and top of the tank
2.5
design pressure or head at the bottom of the tank
the tank depth plus a vent height of 0.5 m. If the height of the vent pipe exceeds 0.5 m or where it is not possible to provide a pressure relief device, the full equivalent height of the vent pipe including frictional loss is taken into account when calculating the design pressure
NOTE See appendix B.
5.2.9 Oil storage tanks shall be installed as specified in clause 15 (see also BS 5410).
5.3 Pressure testing
5.3.1 Types Ito Ill. Before being painted (see 5.4) each tank shall be pressure tested in accordance with appendix A at the manufacturer’s works or on site when the tank is fabricated on site.
Tanks tested on site shall be tested hydraulically. The manufacturer shall provide the purchaser with a copy of the test certificate for each tank supplied. Each tank shall he able to withstand the design pressure. Tanks shall not be used on any site that requires a vent pipe exceeding 0.5 m in height (or equivalent friction head) unless a pressure relief device is fitted (see 2.4 to 2.7).
NOTE The purchaser should inform the manufacturer of the required design pressure [see C.l a)].
5.3.2 Types A to L
5.3.2.1 Types A to K. Before being painted (see 5.4) each tank shall be pressure tested in accordance with appendix A at the manufacturer’s works or on site when the tank is fabricated on site.
Tanks tested on site shall be tested hydraulically. The manufacturer shall provide the purchaser with a copy of the test certificate for each tank supplied.
5.3.2.2 Type L. Where a sectional tank cannot be subjected to a pressure equivalent to the head of oil in the tank and vent pipe (such as by overfihling) it shall be tested by being filled with water to its capacity. The test shall be maintained for a period of24h.
The manufacturer shall provide the purchaser with a copy of the test certificate for each tank supplied.
5.3.2.3 Conditions for types A to L. Each tank shall be able to withstand the design pressure.
NOTE 1 The grade of oil and the pressure to which the tank may be subject in the event of overfilling (see appendix B) or the pressure at which the pressure relief device operates if one is fitted (see clause 11) should be taken into consideration.
NOTE 2 The purchaser should inform the manufacturer of the required design pressure (see C.1 (a)].
5.4 Painting and cleaning
5.4.1 Types I to III. Each tank fabricated at the manufacturer’s work shall, before despatch, be cleaned externally and either:
a) be protected externally with a rust-inhibiting priming paint; or
b) be left unprotected.
The thicknesses of the shell and end plates shall be not less than those given in Table 6.
Tanks shall be supported by a cylindrical skirt, or by supporting brackets, so that the centre of the end plate is at least 300 mm clear of the ground. Inspection openings complying with clause 6 shall be provided in the skirt.
NOTE Above ground tanks, which may become unstable due to wind pressure when empty. should be provided with foundation bolts to prevent overturning.
5.6.10 Type F. For type F tanks end plates shall be dished and flanged and butt welded or lap welded to the shell.
Where the end plates are made in more than one plate the butt joints shall be welded from both sides of the plate.
The dished ends shall be concave to the oil pressure and shall have dimensions as shown in Figure 4. The plate thicknesses and construction shall be as specified in BS 5500, but the thicknesses shall not in any case be less than those given in Table 6 for a tank of similar size.
Tanks shall be supported by a cylindrical skirt, or by supporting brackets so that the centre of the end plate is at least 300 mm clear of the ground. Inspection openings complying with clause 6 shall be provided in the skirt.
NOTE Above ground tanks, which may become unstable due to wind pressure when empty. should he provided with foundation bolts to prevent overturning.
5.6.11 Type G. For type G tanks the bottom end plates shall be welded to the shell from both sides. 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 to 2 700 mm diameter and as shown in Figure 4 for larger diameters.
The thicknesses of the shell and end plates shall be not less than those given in Table 7.
Tanks shall be so erected that the flat bottom is uniformly supported.
NOTE Above ground tanks, which may become unstable due to wind pressure when empty, should be provided with foundation bolts to prevent overturning.
5.6.12 Types Jand K. For tanks of types J and K the seams shall either:
a) be welded inside and outside; or
b) where access for inside welding is impracticable, the top seams shall be 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;
Having determined the pressure at the top of the storage tank, it may be necessary to revise the layout of the oil storage installation. Consideration should therefore be given to the following items and their relevant clauses in this standard:
a) type of tank(s) to be used, cylindrical or rectangular;
b) design pressure of tank(s);
C) vent pipe diameter and length, and unloading device (if any);
d) location of tank(s).
If a revised layout is decided upon, further reference to the appropriate figure and table should be made to check the new conditions.
Pressure developed will vary for different classes of oil. Where E, F, G or H grades of fuel oil are contemplated, it is better to design the storage installation to suit the maximum viscosity fuel oil available and suitable for the oil-burning equipment.
Example 1. Calculate 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 (using Table 15)