BS 3441:1989 download.British Standard Specification for Tanks for the transport of milk and liquid milk products.
1 Scope
BS 3441 specifies requirements for the design. materials and construction of the tanks of tankers intended for the transport of milk and liquid milk products.
NOTE. The titles of the publications referred to in BS 3441 are listed on the inside back cover.
2 Definitions
For the purposes of BS 3441, the following definitions apply.
2.1 tanker. A road or rail transport vehicle fitted with a tank or tanks designed for the storage and transport of milk and liquid milk products.
2.2 atmospheric tank. A tank for the storage and transport of milk or milk products which is designed to be filled and discharged only at atmospheric pressure.
NOTE. Atmospheric pressure during filling of tanks filled through the outlet pipe Is maintained by provision of venting in the manway
2.3 pressure discharge tank. A tank for the storage and transport of milk or milk products which is designed to be filled only at atmospheric pressure but may be discharged at a pressure greater than atmospheric.
2.4 vacuum filling/pressure discharge tank. A tank for the storage and transport of milk or milk products which is designed to be filled under vacuum and discharged at a pressure greater than atmospheric.
3 Tank shell
3.1 Materials and thicknesses
The tank shell shall be constructed of stainless steel plate of either grade 304 S15 or grade 316 516 of BS 1449:
Part 2.
NOTE 1. Guidance on the selection of materials of construction and welding consumdles is given in appendix B, The minimum thickness of the tank shell shall be:
(a) not less than those values specified in BS 5500 or table 1, whichever is thicker, in the case of pressure discharge and vacuum filling/pressure discharge tanks; and
(b) not less than the values shown in table 1, in the case of atmospheric tanks.
NOTE 2. The thickness of the material for the construction of tanks depends upon design considerations such as the cross section of the tank in relation to its length, the type of tank mounting envisaged and the possible inclusion of baffles.
3.2 Shell plate arrangement
If the shell length is produced from more than one single plate, the longitudinal seams shall break joint at intermediate circumferential seams.
3.3 Welding
Welding shall be by either the MIG or the TIG process.
TIG weldng shall comply with the relevant requirements
of BS 3019 : Part 2.
NOTE. A standard for MIG welding of stainlss steels is in preparation.
3.4 Design
Tanks shall be in the form of either a single tank or two or more tanks assembled together on a single chassis. If two or more tanks are used, these shall be assembled either with no direct contact between the tanks or with the end of one tank cut away and the two tanks welded together (see figure 1).
NOTE. Tanks may incorporate one or more baffles.
The ends of all tanks shall be dished. Any internal knudcle radii shall be not less than 25 mm.
As illustrated in figure l.a drain of 25 mm minimum diameter shall be provided in the cavity between two adjacent tanks and no insulation (see clause 7) shall be put in the cavity.
3.5 Internal surfaces and finish
All internal surfaces in contact with the contents of the tank shall be accessible for inspection and shall be so designed and constructed that all surfaces in contact with milk or cleaning solutions are capable of being drained, cleaned and disinfected.
NOTE. Attention is drawn to BS 5305.
All welded internal joints shall be ground level with the parent metal and polished to a 180 grit finish (minimum).
All internal surfaces shall be smooth to the touch and free from visible pits and crevices. Steel plate used for the construction of the tank shell shall be to at least finish no. 2B (i.e. cold rolled, softened and descaled and plannished) of BS 1449 : Part 2.
4 Mounting on chassis
4.1 Drainage and discharge
The tank(s), drainage pipework (see 6.2) and any internal fittings shall be constructed and mounted at a minimum angle of 14 ° above the horizontal, such that they are free draining and provide complete discharge when the tanker is standing on level ground.
4.2 Marking
The following information shall be permanently marked on each tank, adjacent to the manufacturer’s nameplate.
(a) Manufacturer’s name and address.
(b) Manufacturer’s tank serial number. (c) The grade of stainless steel.
(d) Working pressure (and vacuum, where applicable).
(e) Test pressure (and vacuum, where applicable) and date.
(f) The number and year of this standard,
i.e. BS 3441 : 1989.
(g) Where CIP equipment is permanently mounted, the relevant pressure and flow rate for correct operation of the equipment.
(h) The nominal capacity and identification number of each tank.
5 Manways. manway lids and fittings
5.1 Provision of manways
A manway shall be provided in each tank or in each
section of a tank containing baffles.
5.2 Position of manway
The manways shall be mounted on the top of each tank or section, so that in plan view they are positioned centrally in both longitudinal and latitudinal directions.
5.3 Access to the manway
Access to the manway shall be by means of ladder(s) and catwalk(s). The ladder(s) shall be permanently attached to the tanker and shall be of not less than 380 mm inside width. Grab handles shall be fitted. It shall be possible to obtain access to each manway without stepping over another manway.
All catwalks shall be provided with a non-slip, draining walking surtace. If there is one manway. the ladder shall be side or rear mounted. The catwalk shall measure at least 600 mm by 1200 mm and shall extend at least half-way round each manway (see figures 2(a) and (b)).
If there are two manways. the ladder shall be side mounted and between the two manways. The catwalk shall measure.