DEAS 410:2020  
ICS 77.140  
HS 7210.61.00 
 
 
 
 
 
DRAFT EAST AFRICAN STANDARD   
 
Hot-dip aluminium-zinc coated plain and corrugated steel sheets 
Specification 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
EAST AFRICAN COMMUNITY   
 
 
 
 
 
 
 
 
 
 
   
   
© EAC 2020   Second Edition 2020   
 DEAS 410:2020 
 
 
 
Foreword 
 
Development of the East African Standards has been necessitated by the need for harmonizing 
requirements governing quality of products and services in East Africa. It is envisaged that through 
harmonized standardization, trade barriers which are encountered when goods and services are 
exchanged within the Community will be removed. 
 
In order to achieve this objective, the Partner States in the Community through their National 
Bureaux of Standards, have established an East African Standards Committee.  
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. 
 
© East African Community 20202020 — All rights reserved* 
 
East African Community  
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Tanzania  
Tel: 255 27 2504253/8  
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© EAC 2020 — All rights reserved   
 
EAST AFRICAN STANDARD  DEAS 410:2020  
 
 
 
Hot-dip aluminium-zinc coated plain and corrugated steel sheets 
Specification 
 
1 Scope 
 
This Draft East African Standard specifies requirements, sampling and test methods for continuous 
hot- dip Aluminium-Zinc (AZ) coated plain and corrugated steel sheets for roofing, cladding, fencing, 
fabrication and general use. 
This standard does not cover the special purpose profiles. 
 
The Aluminium-Zinc alloy composition by mass is nominally 55% Aluminium, 1.6% Silicon and 
balance Zinc. 
 
The product is intended for applications where the corrosion characteristics of Aluminium coupled 
with those of Zinc are most desired. 
 
2 Definitions 
 
For the purpose of this standard, the following definitions shall apply: 
 
2.1  
AZ Coated Sheets 
Steel sheets with a uniform coating of Aluminium-zinc applied by the hot-dip process. 
 
2.2.1  
Corrugated Sheets 
AZ coated steel sheets, which are mechanically profiled to obtain a regular shape which can either 
be sinusoidal as shown in Figure 1, or any other profile.  
 
 
 
 
 
 
 
 
 
 
 
Figure 1 — Profile of corrugated sheets 
 
2.4  
Thickness 
The thickness of base metal 
 
2.4  
Plain 
The flat or even sheets without any relief forms 
 
2.5  
Pitch 
The distance between two corresponding and consecutive points on the corrugated steel sheet 
along its width 
 
2.6 Coating mass  
This is the total amount of the AZ alloy including both sides of the sheet expressed in grams per square metre 
(g/m2) 
  
  
 
1 © EAC 2020 — All rights reserved  
 DEAS 410:2020 
 
 
3 General requirements 
 
3.1 Dimensions 
 
3.1.1 Expression of dimensions 
 
3.1.1.1 Width and length  — The dimensions of width and length shall be expressed in millimetres. 
 
3.1.1.2 Thickness  — The thickness of AZ coated plain and corrugated sheets shall be expressed in  
gauge*. When measured in accordance with clause 8.2.1,the corresponding thickness of base metal 
in millimetres shall be as specified in Table 1 
 
3.1.2 Width —The width of plain and corrugated AZ coated sheets when measured in accordance  
with 8.2.4 shall be as specified in Table 2. 
 
3.1.3 Length — when measured in accordance with 8.2.2 the length of sheets shall be as specified  
in Table 3. 
 
3.1.4 Squareness  — when measured in accordance with 8.2.3 the distance between diagonally  
opposite corners of the sheet shall not differ by more than 10 mm. 
 
3.2 Profile 
 
3.2.1 Depth — The depth of corrugations shall be 18 ±  1.5 mm, when measured in accordance  with 
8.2.6. 
 
3.2.2 Pitch — The pitch of the corrugations shall be 76 ± 2 mm when measured in accordance with  
8.2.5. 
 
3.3 Tensile Strength — The tensile strength of plain and corrugated AZ coated sheets when  
determined in accordance with 8.2.7 shall be not less than 300 N/mm2. The yield strength shall be 
not less than 210 N/mm2.  
3.4 Resistance to Bending — When tested in accordance with 8.2.8 the sheet shall not crack,  
flatter or splinter. 
 
3.5 Freedom from Defects — The sheets shall be uniform, clean and free from defects that  would 
adversely affect their use. 
 
3.6 Finish — Unless other wise desired by the purchaser, the AZ coated sheets shall have a  normal 
spangle finish as a result of the unrestricted growth of alloy crystals during normal solidification of 
‘Mill Finish’.  
 
3.7 Coating adherence  – The sheet shall not show any cracks when tested in accordance to 8.2.8 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
* Reference gauge in this standard is the BS American Brown and Shaper’s gauge. 
  
  
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© EAC 2020 — All rights reserved   
         DEAS 410:2020
  Table 1 — Base metal thickness of plain and corrugated sheets  
             
  GAUGE  THICKNESS (mm)   TOLERANCE ( ±%)  
 32  0.20     10     
 30  0.25    10     
 28  0.32    10     
 26  0.40    10     
 24  0.50    10     
 22  0.63    5     
 21  0.70    5     
 20  0.80    5     
 19  0.90    5     
 18  1.00    5     
 16  1.20    5     
 14  1.50    5     
 NOTE:  
1. Due to the inter -metallic alloy layer in AZ coated steel sheets, subtract 0.01mm from the thickness values in   
     this table to obtain the base metal thickness. 
2. 32 Gauge Sheets to be marked NOT FOR ROOFING.       
  Table 2 — Width of plain and corrugated sheets  
        
  Width of plain  sheets before 
corrugation(mm), ±  2.5% 
 Number of corrugations 
 Total corrugated wi dth 
(mm) ± 2.5% 
    
1220  14    1100     
1150  13    1025     
1070  12    950     
1000  11    875     
914  10    800     
845  9    725     
762  8    645     
        
  Table 3 — Length of plain and corrugated sheets  
            
  LENGTH, m m, + 0.5 %, - 0 %     
  Plain Sheets     Corrugated Sheets   
  2 000 2 000     
  2 500 2 500     
  3 000 3 000     
Note: Other lengths may be used for special order only as agreed between the purchaser and the manufacturer. 
 
4 Aluminium-zinc coating process -criteria of conformity 
 
4.1 General Requirement  
The steel sheets shall be manufactured in accordance with accepted current practice and shall be 
from rolled mild steel processed to meet the requirements of ISO 2566 or equivalent. The sheets 
shall be true to size, homogeneous, with no trace of discontinuity of the Aluminium-Zinc coating. 
They shall also be free from holes, tears, twists, cambers and damaged edges and corners. 
Corrugations shall be parallel to the edges of the sheets. 
 
4.2 Aluminium-Zinc (AZ) Coating 
 
4.2.1 The coating shall be carried out by the hot- dip process in a coating bath containing about  55% 
Aluminium, 1.6% silicon and the balance zinc. The minimum mass of AZ coating on the two sides of 
sheet and the corresponding thickness of coating on each side shall conform to the minimum mass 
of coating given in Table 4. 
 
 
© EAC 2020 — All rights reserved   
 DEAS 410:2020 
 
4.2.2 The coating mass shall conform to the requirements presented in table 4 for the specified  
coating designation when tested according to methods specified in 7.1.  
 
4.2.3 AZ coating adherence shall be such that there shall be no flaking or splintering in the finished  
AZ plain or corrugated steel sheets, when tested in accordance with 7.2 
 
4.3 Classification - AZ plain and corrugated steel sheets shall be classified into seven classes  
depending on the mass of AZ coating applied to meet different service and environmental conditions. 
The classes shall be as specified in Table 4 
 
Table 4 — Classification of AZ coated plain and corrugated steel sheets. 
 
 Coating class  Minimum coating mass  Minimum coating mass  Minimum  coating 
  on two sides by weight  on   two sides   by  thickness  on  both  sides  
  method (g/m2) chemical method  (µm)  
   (g/m2)    
 AZ 85 85 71  19  
 AZ 100 100 85  23  
 AZ 120 120 102  27  
 AZ 150 150 130  35  
 AZ 165 165 140  38  
 AZ 185 185 160  43  
 AZ 200 200 170  46  
 NOTE: Values in column 4 of table 4 are for information only     
5 MARKING  AND PACKAGING      
 
5.1 Conforming Sheets 
Each AZ coated plain or corrugated steel sheet conforming to this standard shall be permanently and 
indelibly marked with the following: 
 
(i) Manufacturer’s name and/or trade mark.. 
(ii) The base metal thickness expressed in gauge with word “GAUGE” in full and millimetre.   
(iii) The coating class of sheet  
(iv) The batch identification. 
(v)  Gauge 32 sheets, should be clearly marked “not for roofing” font size 12 mm width in every 1m 
along the length. 
 
5.2 Non-Conforming Sheets — All non-complying sheets shall be identified by cutting off all four corners 
at least by 75 mm along the edges diagonally and shall be marked “Rejected” with indelible ink.  
 
5.3 Packaging 
Where sheets and coils are packed, each package shall be legibly and indelibly marked with the 
following information: 
a) manufacturer’s name and/or trade name; 
b) classified symbol (including shape symbol for profiled sheets); 
c) symbol indicating coating mass; 
d) dimensions; and number of sheets or mass where applicable. 
 
6 Sampling  
The following sampling procedure shall be applied in determining whether a lot complies with the 
relevant requirements of this Standard. The samples so taken shall be deemed to represent the lot. 
 
6.1 Sample for Inspection and Dimensional Tests — From the lot, take at random the number  of 
sheets shown in column 2 of Table 5 relative to the appropriate grouping in column 1. 
 
6.2 Sample for other Tests — From the sample taken in accordance with 6.1 take at random  one 
sheet. 
 
  
  
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© EAC 2020 — All rights reserved   
  DEAS 410: 2020
 Table 5 —Sampling plan  
  
 Number of sheets  Sample for inspection and dimensional test, number of sheets  
1-16 1  
17-48 2  
49-100 3  
101-160 4  
161-200 5  
over 200  5 per 200 sheet   
 
7 Testing for AZ coating 
 
7.1 Mass of AZ Coating 
 
7.1.1  
 
7.1.2 Chemical method —  The method prescribed in Annex A shall be used. The results, in g/m2, 
shall meet the requirements shown in Table 4. 
 
In case of a dispute, the method prescribed in Annex A of this standard shall be used. 
 
NOTE Coating mass may also be determined by converting coating thickness, measured with magnetic gauges or by 
spectrometry, into coating mass. (S ee ISO 21781 and ISO 34972) 
 
7.2 Coating adherence test 
 
 
 
8 Inspections andtesting 
 
8.1 Inspection — The sample taken in accordance with clause 6 shall be inspected for  compliance 
with 3.5, and 5.1. 
 
8.2 Dimensions. 
 
8.2.1 Thickness — Using a micrometer screw gauge or a pair of callipers, measure to the nearest  
0.01 mm the thickness of each sheet in the sample at any point at least 10mm from an edge and end 
of the sheet after removing the coating as described in A.4 of Annex A. 
 
8.2.2 Length — Place each sheet in the sample in turn on a flat rigid surface. Measure to the  nearest 
1 mm the length of each sheet in the sample along the centre line of the sheet. 
 
8.2.3 Squareness —  Place each sheet in the sample in turn on a flat rigid surface. Measure to the  
nearest 1 mm the distance between the diagonally opposite corners of each sheet in the sample and 
record to the nearest mm any difference between the two measurements on a sheet.  
 
 
 
 
 
 
1 ISO 2178:1982, Non magnetic coatings on magnetic substrates — Measurement of coating thickness – Magnetic 
 
2 ISO 3497:2000, Metallic coatings – Measurement of coating thickness – X-ray spectrometric methods  
© EAC 2020 — All rights reserved  
 
 
 
 
 
method 
 
 
 
 
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 DEAS 410:2020 
 
8.2.4 Width 
 
8.2.4.1 Plain sheets 
Place each sheet in the sample in turn on a flat rigid surface. Measure to the nearest 1 mm across 
the width of the sheet. 
 
8.2.4.2 Corrugated sheets 
Place each of the sheets in the sample in turn on a flat rigid surface and measure to the nearest 1 
mm across the width of the sheet. Choose at random a cross-section of the sheet and if, because of 
the springy nature of the sheet, the underside of the downwards corrugations or troughs are not all in 
contact with the supporting surfaces, apply sufficient pressure to the upper surfaces of the sheet to 
bring the lower surface into full contact with the supporting surface. Ensure that the application of 
pressure causes no deformation of the sheet other than that needed to bring the corrugations into 
contact with the rigid surface. 
 
Place the width gauge appropriate to the type of sheet being tested across the sheet a chosen 
cross-section and at rigid-angles to the sides of the sheets and adjust the gauge to fit firmly over the 
outermost corrugations. Determine whether the width of the sheet complies with the requirements of 
Table 2. Both edges of the corrugated sheet shall be turned upwards. 
 
8.2.5 Pitch 
 
With the sheet in contact with a flat surface, place a transparent graduated rule on edge across the 
sheet so that it rests perpendicularly on the crests of two adjoining corrugations far from the points of 
contact, and read the distance between them to the nearest 1mm. Repeat the process to improve 
your results and take the average of five readings. 
 
8.2.6 Depth of Corrugations 
With the initial rule lying flat across the corrugations at the edge of the sheet, use another graduated 
rule or a pair of calipers to measure the perpendicular distance between the initial rule and the rigid 
support. 
 
8.2.7 Tensile strength 
 
From the sample taken in Clause 6, prepare a tensile test specimen as described in A.4 of Annex A 
by cutting a strip of 30mm × 80mm, such that the length of the specimen is transverse to the 
direction of rolling of the sheet. The portion of sheet from which the test piece is cut shall be carefully 
flattened. Determine the tensile strength of the specimen as described Annex A. 
 
If the tensile strength of the test specimen fails the requirements of 3.3 prepare two further test 
specimens and determine their tensile strength. If both specimens comply with the requirements, 
discard the results of the first specimen, but if either of the additional specimen fails to meet the 
requirements, deem the sheet and the lot to be defective. 
 
8.2.8 Bend test and coating adherence test 
A test specimen selected in accordance with clause 6 and shall be prepared measuring 10mm wide 
and length 120mm. It shall be cut with its length transverse to the direction of rolling of the sheet. 
 
Carefully bend the strip round a drum of diameter 38mm (mandrels may also be used) until the 
edges of the specimen are approximately semi-circular. If the specimen flakes or cracks, prepare 
and test two further specimens in the same way. If both these tests specimen comply with the 
requirements of 3.4 and 3.5, discard the results obtained on the first specimen, but if either of the 
two, crack at the bend, deem the sheet and lot to be defective. 
 
The test shall consist of subjecting the test piece of deformation by bending in one direction. The test 
piece shall either be bent mechanically or gripped in hand- operated device (mandrels may also be used) 
and bent until the two legs of the test piece are parallel to each other, i.e. through 180 degrees. 
 
A second test piece shall be bent in the opposite direction. 
 
The sheets shall be bent round a diameter of 38mm 
  
  
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© EAC 2020 — All rights reserved   
 DEAS 410:2020 
 
 
Annex A — Reference method for determination of the AZ coating mass 
(Normative) 
 
A.1 Principle 
 
Using a specimen with a surface area of at least 5000 mm2, the loss of mass in grams when the 
coating is dissolved, multiplied by 200, will represent the coating mass in grams per square meter of 
the product, (for both sides) 
 
NOTE To verify the mass of coating, three specimens shall be cut and tested, one from the mid-width position and one from 
each side, no closer than 25mm from the side edge of a sample piece approximately 300mm in length on the as coated width 
(see clauses 7.1.2.1 and 7.1.1.2). 
 
A.2 Reagent and preparation of the solution 
 
Reagent 
Hydrochloric acid (HCI = 1.19 g/cm3)  
Hexamethylenetetramine or Antimony tri-chloride 
 
Preparation of the solution  
The Hydrochloric acid is diluted with water (de-ionized or distilled) in the ratio of one part 
concentrated HCl to one part water (50% dilution). 
 
Hexamethylenetetramine or Antimony tri-chloride is then added, stirring, 3.5g per litre of dilute 
Hydrochloric acid solution. 
 
This prepared solution permits the execution of numerous successive dissolutions under satisfactory 
conditions of attack of the coating, both from the point of view of speed and accuracy. 
 
A.3 Apparatus 
 
A balance capable of weighing samples to an accuracy of 0.01g. For the test, use a take-off device. 
 
A.4 Procedure 
 
The following operations are applied to each sample: 
 
a) If necessary, degrease the sample with an organic solvent, which will not attack the coating, then 
dry the sample;  
b) Weigh the sample to an accuracy of 0.01g; (W 1) 
 
c) Place the sample in the hydrochloric acid solution with hexamethylenetetramine or Antimony 
Chloride inhibitor at ambient temperature (20 °C to 25 °C). 
 
Leave the sample immersed in the solution until the release of hydrogen ceases or only a few 
bubbles are released; 
 
d) After the attack, wash the sample and brush under running water, dry with a cloth and then by 
heating to around 100 °C and cool or dry by blowing with warm air;  
e) Weigh the sample again to an accuracy of 0.01g; (W 2) 
 
f) Determine the difference between the mass of the coated sample and that of the sample without 
its coating. This difference, calculated in grams, represents the mass (m) of the coating. 
 
A.5 Calculation 
 
The coating weight shall be obtained from the following formulae. Method 1 shall be the reference 
method in case of a dispute: 
 
  
  
 
7 © EAC 2020 — All rights reserved  
 DEAS 410:2020 
 
 
Method 1 C = (W1  − W2 ) ×106  
   
 1   A   
      
 C = (W1 − W2 )g ×106= 200(W − W ) g / m2
    
 1   5000mm2  12 
Method 2 C2 =   (W1 − W2 ) × t × 7850 
   
    W2    
Where 
C =Zinc coating in g/m2 
A =area of test specimen (length × width),  
W1 = Weight (g) of test piece before stripping, 
W2 = Weight (g) of test after stripping (base metal)  
t =thickness (mm) of test piece after stripping (base metal)  
106 = conversion factor ( W is in g, t in mm, while C is in g/m2 
7850 = density of steel, kg/m3 
NOTE Method 1 can be used for regular pieces of specimen (either square or rectangular). In cases where it’s difficult to cut  
regular test pieces, e.g the heavier sheet gauges, method 2 may be used. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
  
  
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© EAC 2020 — All rights reserved   
 DEAS 410:2020 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
  S 
  
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