DEAS 783: 2020 
ICS 77.140  
© EAC 2020                                                                                                                         Second Edition 2020  
 
DRAFT EAST AFRICAN STANDARD 
Stainless steel storage tanks ― Specification 
EAST AFRICAN COMMUNITY 
 
 
 
 
 
 
 
 
   
  DEAS 783: 2020 
ii © EAC 2020 – All rights reserved
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 DEAS 783: 2020 
© EAC 2020 – All rights reserved  iii
 Foreword 
Development of the East African Standards has been necessitated by the need for harmonizing requirements 
governing quality of products and services in the East African Community. It is envisaged that through 
harmonized standardization, trade barriers that are encountered when goods and services are exchanged 
within the Community will be removed.  
In order to achieve this objective, the Community established an East African Standards Committee mandated 
to develop and issue East African Standards.   
The Committee is composed of representatives of the National Standards Bodies in Partner States, together 
with the representatives from the private sectors and consumer organizations. Draft East African Standards 
are circulated to stakeholders through the National Standards Bodies in the Partner States. The comments 
received are discussed and incorporated before finalization of standards, in accordance with the procedures 
of the Community. 
East African Standards are subject to review, to keep pace with technological advances. Users of the East 
African Standards are therefore expected to ensure that they always have the latest versions of the standards 
they are implementing .  
EAS 783 was prepared by Technical Committee EASC/TC 035, Steel and steel products . DEAS 783: 2020 
iv © EAC 2020 – All rights reserved
  
 DRAFT EAST AFRICAN STANDARD DEAS 783: 2020
 
© EAC 2020 – All rights reserved 1 
 Stainless steel storage tanks ― Specification  
1 Scope 
This Draft East African Standard specifies constructional requirements, sampling and test methods for non -
pressurized stainless steel storage tanks for food related items.  
2 Normative references 
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. 
 
ASTM A 240/A 240M-07, Standard speciﬁcation for chromium and chromium-nickel stainless steel plate, 
sheet, and strip for pressure vessels and for general applications   
ISO 6892 -1, Metallic materials — Tensile strength test 
ISO 3651-1:1998 Determination of resistance to intergranular corrosion of stainless steels — Part 1: Austenitic 
and ferritic-austenitic (duplex) stainless steels — Corrosion test in nitric acid medium by measurement of loss 
in mass (Huey test) 
ISO 3651-2, Determination of resistance to intergranular corrosion of stainless steels — Part 2: 
Ferritic,austenitic and ferritic-austenitic (duplex) stainless steels — Corrosion test in media containing sulfuric 
acid 
ISO 9328-7, Steel flat products for pressure purposes — Technical delivery conditions — Part 7: Stainless 
steels 
ISO 16143-1, Stainless steels for general purposes — Part 1: Corrosion-resistant flat products 
3 Terms and definitions 
For the purposes of this standard, the following terms and definitions shall apply. 
3.1 
bright polished finish 
shining reflective finish obtained by polishing the surface without complete obliteration of previously existing 
grinding marks or other surface texture 
3.2  
defective  
tank that fails in one or more aspects to comply with the appropriate requirements of this standard  
2 © EAC 2020 – All rights reserved
 3.3 
directional satin finish 
finish obtained by so grinding the surface with fine abrasives (without subsequent polishing) as to leave a silky 
appearance, with the abrasive marks running in the same general direction 
4 Constructional requirements  
4.1 General requirements 
4.1.1 Material  
The stainless steel used under the specified chloride level of the foodstuff, shall be ISO type 304L, type 316L, 
type 304, or type 316, as specified by the purchaser, and of the relevant composition given in Table 1. Grade 
304 and 316 are more preferable for food and surgical use.   
 
Table 1 — Typical chemical composition of stainless steel  
 
Mass fraction,% 
 Steel 
grade   C   Si   Mn   P   S   N   Cr   Cu   Mo   Nb   Ni   Ti   Others 
   max. max. max. 
        
Austenitic corrosion-resisting grades  
 
X2CrNi
18-9   ≤0,030   ≤1,00   2,00   0,045   0,015   ≤0,10   17,5 to 
19,5   —   —   —   8.0 to 
10,5   —   —  
 
X5CrNi
18-10   ≤0,07   ≤1,00   2,00   0,045   0,015   ≤0,10   17,5 to 
19,5   —   —   —   8.0 to 
10,5   —   —  
 
X2CrNi
Mo17-
12-2   ≤0,030   ≤1,00   2,00   0,045   0,015   ≤0,10   16,5 to 
18,5   —   2,00 
to 2,50  —   10.0 to 
13.0   —   —  
 
X5CrNi
Mo17-
12-2   ≤0,07   ≤1,00   2,00   0,045   0,015   ≤0,10   16,5 to 
18,5   —   2,00 
to 2,50  —   10,0 to 
13,0   —   —  
a Elements not listed in this table may not be intentionally added to the steel without the agreement of the 
purchaser, except for finishing of the cast. All appropriate precautions are to be taken to avoid the addition of 
such elements from scrap and other materials used in production, which would impair mechanical properties 
and the suitability of the steel 
Determination of chemical composition of the listed stainless steel grades can be done by either of the 
following standards; ISO 14284, ISO 4937, ISO 4938, ISO 4939, ISO 4940, ISO 10138, ISO 13898-1, ISO 
13898-2, ISO 15355 and ISO 19272. 
  
© EAC 2020 – All rights reserved  3
 Table 2— Permissible deviations between the product analysis and the limiting values given in Table 2 for the 
cast analysis 
 
 
Element  Specified limits, cast analysis  
% (mass fraction) Permissible deviationa 
% (mass fraction) 
 
 
 
Carbon  ≤0,030 +0,005 
>0,030 ≤0,20 ±0,01 
>0,20 ≤0,60 ±0,02 
>0,60 ≤1,20 ±0,03 
 
 
Silicon  ≤1,00 +0,05 
   
   
 
 
Manganese  ≤1,00 +0,03 
>1,00 ≤2,00 ±0,04 
>2,00 ≤15,0 ±0,10 
 
Phosphorus   ≤0,045 +0,005 
>0,045 0,070 ±0,010 
 
 
Sulfur  ≤0,015 +0,003 
>0,015 ≤0,030 ±0,005 
≥0,10 ≤0,50 ±0,02 
 
 
Chromium    
>15,0 ≤20,0 ±0,20 
   
 
 
Molybdenum    
   
>1,75 ≤8,0 ±0,10 
 
 
 
Nickel    
   
>5,0 ≤10,0 ±0,10 
>10,0 ≤20,0 ±0,15 
   
 
Nitrogen   ≤0,10 +0,01 
≥0,10 ≤0,60 ±0,02 
 
Aluminium  ≥0,05 ≤0,30 ±0,05 
>0,30 ≤1,50 ±0,10 
Boron  ≤0,010 +0,000 5 
  ≤1,00 +0,04  
4 © EAC 2020 – All rights reserved
 Copper >1,00 ≤5,0 ±0,10 
Niobium  ≤1,00 +0,05 
Tungsten   ≤3,00 +0,05 
Vanadium  ≤0,50 +0,03 
 
Titanium   ≤1,00 +0,05 
>1,00 ≤3,0 ±0,07 
a        ± means that in one cast, the deviation can occur over the upper value or under the lower value of the 
specified range in Table 1, but not both at the same time. 
 
4.1.2 Construction  
Tanks shall be made by stamping, pressing, or fabricating, or by a combination of two or more of these 
methods.  
4.1.3 Joints  
All joints shall fit closely, and the whole length of each joint shall be welded. The welded joints shall be ground 
flush with the working face. No solder shall be used on joints. 
4.1.4 Welds  
Welds shall be fusion welds done by the seaming process or by any other welding process that produces a 
weld having mechanical properties and corrosion resistance of at least the same order as those of the parent 
metal. When tested in accordance with ISO 6892-1, the strength of the welded point, shall be similar to the 
strength of parent material, as shown in Table 3. 
 
 
 
 
 
 
 
 
 
 
 
 
  
© EAC 2020 – All rights reserved  5
 Table 3  — Mechanical properties  of Stainless Steel 
 
 
4.1.5 Finish  
All exposed surfaces shall be free from buckles, dents, pits, deep scratches, and other defects, and shall have 
a medium directional satin or a bright polished finish, as specified by the purchaser. The tanks shall be free 
from dirt, grease, graphite, and other foreign matter.  Steel designation  
 
 Product  
Form 
 Proof 
strength  Tensile  
strength  Elongation 
after fracture  Resistance to 
intergranular corrosion  
 
 
Name  
 
ISO 
number   
 
(Class) Rp0,2 Rp1,0 Rm A80d 
in the 
delivery 
condition in the 
sensitized 
condition  
MPa min.   
MPa  
% min.  
 
X2CrNi18-9 4307-304-
03-I C  
2R 220 250 520 to 
720 45  
 
yes  
yes 
 
X5CrNi18-10  
 
 
4301-304-
00-I C 
2R  230 260 540 to 
750 45  
 
yes  
 
no 
X2CrNiMo17-
12-2  
 
4404-316-
03-I C  
2R 240 270 530 to 
730 40 yes  
yes 
 
X5CrNiMo17-
12-2  
4401-316-
00-I C 
2R 240 270 530 to 
730 40  
 
yes  
no  
6 © EAC 2020 – All rights reserved
 4.2 Specific requirements 
4.2.1 Design and dimensions 
The design of the tank shall either be square, round, rectangle or cylindrical or as may be agreed between the 
purchaser and the manufacturer. The dimensions shall be in accordance with the purchaser and manufacturer 
agreement with respect to design requirements. The minimum thickness of the material used for 
manufacturing the tank shall be 0.3 mm. Normal tolerances of 0.015 mm  shall apply to the thickness of the 
material. 
4.2.2 Construction  
The tank shall be grooved around the circumference with minimum number of five grooves. The tank shall 
consist of two holes at the top, one for the inlet and other for tank breathing, and two holes at the bottom, one 
for the outlet and the other for draining during cleaning.  
Note: Other construction requirements not covered under this standard can be in accordance with the 
agreement between manufacturer and purchaser. The preferred tank capacities and dimensions can be as 
per annex A. 
4.2.3 Leakage 
The tank shall not show any leakage when tested in accordance with 7.3. 
4.2.4 Hydrostatic pressure  
The tank shall withstand hydrostatic force when tested in accordance with 7.4. 
5 Marking  
Each tank shall be legibly and indelibly marked with the following information on the surface of the tank:  
a) manufacturer's name and address;  
b) capacity of the tank in litres; 
c)  Stainless steel grade,  
d) batch number of the tank; and 
e) thickness of the material. 
6 Sampling and compliance  
6.1 Sampling  
6.1.1 General 
The sampling procedures in 6.1.2 and 6.1.3 shall be applied in determining whether a lot complies with the 
appropriate requirements of this standard. The samples so taken shall be deemed to represent the lot for the 
respective properties. 
NOTE This clause applies to the sampling for inspection and testing before acceptance or rejection of single lots 
(consignments) in cases where no information about the implementation of quality control or testing during manufacture is 
available to help in assessing the quality of the lot. It is also used as the procedure for adjudications in cases of dispute.   
© EAC 2020 – All rights reserved  7
 6.1.2 Sample for inspection  
From the lot, random sampling shall be done in accordance with Table 3. 
Table 3 — Sample for testing and inspection 
Lot size Sample size 
Sample for inspection Sample for testing Defective acceptance 
number 
Less than 20 All 1 0 
20 – 100 20 2 1 
 
6.1.3 Sample for testing  
From each sample taken in accordance with 6.1.2, random sampling of the number of tanks relative to the 
appropriate lot size shall be done in accordance with Table 3. 
6.2 Compliance 
The lot shall be deemed to comply with the requirements of this standard, if after inspection and testing 
a) the number of defectives found in the sample taken in accordance with 6.1.2 does not exceed the 
appropriate acceptance number given in Table 3; and 
b) no defective is found in the sample taken in accordance with 6.1.3. 
7 Inspection and methods of test  
7.1 Inspection  
Inspection of samples shall be done in accordance with 6.1.2 for compliance with the appropriate 
requirements of clauses 4, 5, and 6 other than those given in 4.1.1. 
7.2 Chemical analysis of stainless steel  
Use the method described in ASTM A 751, or any other approved method, to determine the chemical 
composition of the steel used in the manufacture of each tank in the sample taken in accordance with 6.1.3.  
7.3 Leakage test 
Fill water to the full capacity of the tank under room temperature and atmospheric pressure and leave it for 15 
min. Observe if there is any leakage. 
7.4 Pressure test 
Fill water to the full capacity of the tank under room temperature and atmospheric pressure and leave it for 15 
min.  
 
  
8 © EAC 2020 – All rights reserved
 The tank shall withstand the hydrostatic pressure calculated by the following formula:  
P = ρhg 
where: 
P is the hydrostatic pressure; 
ρ is the density of food stuff; 
h in the height of the tank; and 
g is the acceleration due to gravity.  
© EAC 2020 – All rights reserved  9
 Bibliography 
SANS 906:2006, Stainless steel wash-hand basins  Published by South Africa Bureau of Standards 
Henkel and Pense, 2002, Structure and properties of engineering materials , fifth edition, published by Mc 
Graw – Hill, New York 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
  
10 © EAC 2020 – All rights reserved
  
Annex A 
(Informative) 
Table A.1 The preferred tank capacity and dimensions for circular stainless steel tanks 
Tank Capacity (Litres, L)  Diameter of Tank (mm)  
± 10 mm  Tank Height (mm)            
± 10 mm  Thickness (mm)                
± 0.015 mm  
60 430 450 0.4 
120 480 700 0.4 
250 760 550 0.4 
350 760 775 0.4 
450 760 995 0.4 
650 760 1435 0.4 
750 760 1655 0.4 
1000 960 1435 0.4 
1250 960 1740 0.5 
1500 960 2075 0.5 
1700 1180 1560 0.5 
2000 1180 1830 0.6 
2500 1420 1600 0.7 
3000 1420 1925 0.7 
4000 1610 2030 0.7 
4500 1610 2230 0.7 
5000 1610 2820 0.7 
7050 1610 3500 0.7 
10000 2200 2910 0.7 
 DEAS 783: 2020 
 
© EAC 2020 – All rights reserved