ICS 55.100  
 
Reference number  
DRS 463:2021  
© RSB 2021  
  
 RWANDA 
STANDARD  DRS 
463  
 
First edition  
2021 -mm-dd 
 
Metallic crown caps — Specification  
   
DRS 463: 2021  
©RSB 2021 - All rights reserved                  ii 
 In order to match with technological development and to keep continuous progress in industries, 
standards are subject to periodic review. Users shall ascertain that they are in possession of the latest 
edition  
 
 
 
 
 
 
 
 
© RSB 2021  
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized 
in any form or by any means, electronic or mechanical, including photocopying and microfilm, without 
prior written permission from R SB. 
Requests for permission to reprodu ce this document should be addressed to : 
Rwanda Standards  Board  
P.O Box 7099 Kigali -Rwanda  
KK 15 Rd, 49  
Tel. +250 788303492  
Toll Free: 3250  
E-mail: info@rsb.gov.rw  
Website: www.rsb.gov.rw  
ePortal: www.portal.rsb.gov.rw   DRS 463: 2021  
iii                ©RSB 2021 - All rights reserved  
 Contents  Page 
Foreword  ................................ ................................ ................................ ................................ ............................  iv 
1 Scope  ................................ ................................ ................................ ................................ ......................  1 
2 Normative references  ................................ ................................ ................................ ............................  1 
3 Terms and definitions  ................................ ................................ ................................ ...........................  1 
4 Requirements  ................................ ................................ ................................ ................................ .........  2 
4.1 General requirements  ................................ ................................ ................................ ...........................  2 
4.1.1  Crown shell  ................................ ................................ ................................ ................................ ............  2 
4.1.2  Liner  ................................ ................................ ................................ ................................ ........................  2 
4.1.3  Crown cap assembling  ................................ ................................ ................................ .........................  2 
5 Specific requirements  ................................ ................................ ................................ ...........................  3 
5.1 Crown shell/base steel  ................................ ................................ ................................ ..........................  3 
5.2 Liner  ................................ ................................ ................................ ................................ ........................  3 
5.3 Moisture content  ................................ ................................ ................................ ................................ .... 3 
6 Dimensions o f the crown caps  ................................ ................................ ................................ ............  4 
6.1 Crown cork dimension  ................................ ................................ ................................ ..........................  4 
6.2 Pry off crown profiles ................................ ................................ ................................ ............................  5 
6.3 Twis t off or Universal crown profiles  ................................ ................................ ................................ .. 6 
7 Packaging and storage  ................................ ................................ ................................ .........................  6 
8 Marking  ................................ ................................ ................................ ................................ ...................  6 
9 Sampling  ................................ ................................ ................................ ................................ ................  7 
Annex  A (normative) Dete rmination of overall migration of constituents of plastics materials and 
articles intended to come in contact with foodstuffs - Method of analysis  ................................ .... 8 
A.1 Types of simulants  ................................ ................................ ................................ ................................  8 
A.2 Selection of standard test conditions and simulants for different foodstuf fs ................................  8 
A.3 Selection of Sample  ................................ ................................ ................................ ............................  10 
A.4 Procedure  ................................ ................................ ................................ ................................ .............  10 
A.5 Determination of Amount of Extractive  ................................ ................................ .............................  10 
 DRS 463: 2021  
©RSB 2021 - All rights reserved                  iv 
 Foreword   
Rwanda Standard s are prepared  by Technical Committees and approved by R wanda Standards Board (RSB) 
Board  of Directors in  accordance with the procedures of RSB, in compliance with Annex 3 of the WTO/TBT 
agreement on the preparation, adoption and application of standards.  
The main task of technical committees is to prepare national standards.  Final Draft Rwanda S tandards 
adopted by Technical committ ees are ratifie d by me mbers of RSB Board of Director s for publication and 
gazettment as Rwanda Standards.  
DRS 463  was prepared by Technical Committee RSB/TC 020, Packaging and packaging materials . 
In the preparation of this standard, reference was made to the following standard s:  
1) IS 1994 : 1987  Crown closures  
2) US 2240 :2020  Metallic crown caps — Specification  
The assistance de rived from the above source is hereby acknowledged with thanks.  
Committee membership  
The following organizations were represented on the Technical Committee on Packaging and packaging 
materials. (RSB/TC 020) in the preparation of this standard.  
Ministry of Trade and Industry (MINICOM)  
Rwanda Inspectorate, Competition and Consumer Protectio n Authority (RICA)  
National Agricultural Export Development Board (NAEB)  
University of Rwanda -College of Science and Technology (UR -CST)  
BRALIRWA Plc. 
Skol  Brewery Ltd  
NITRIVO food and beverages Ltd  
Rwanda  Standards Board  (RSB) – Secretariat  DRS 463: 2021  
v                ©RSB 2021 - All rights reserved  
 Introduction   
Metal crown caps are well known because of their strict associati on with glass bottles. In fact, crown corks are 
designed to secure seal in capping applications with glass and aluminium bottles in the brewing and beverage 
market for soft-drinks and alcoh olic beverages.   
Efficient packaging is of great importance for the distribution and the protection of goods to ensure food 
safety. Insufficient or inappropriate packaging can lead to damage or wastage of the contents of the pack.DRS 463 : 2021  
1                ©RSB 2021 - All rights reserved  
 Metallic crown caps — Specification  
1 Scope  
 This Draft  Rwanda Standard specifies the requirements , sampling and test methods  for metallic crown caps , 
also known as crown corks  or crow seal , designed to secure seal in capping applications with glass and 
aluminium bottles . 
2 Normative references   
The following documents are referred to in the text in such a way that some or all of their content constitutes 
requirements 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.  
ISO 11950, Cold-reduced tinmill product s — Electrolytic chromium/chromium oxide -coated steel  
ISO 11949, Cold -reduced tinmill products — Electrolytic tinplate  
RS EAS 354 , Plastic containers for up to 5 litres capacity — Specification  
ISO 15512, Plastics — Determination of water content  
RS ISO 28 59-1, Sampling procedures for inspection by attributes — Part 1 : Sampling  schemes indexed by 
acceptance quality limit (AQL) for lot -by-lot inspection  
3 Terms and definitions   
For the purposes of this standard, the terms and definitions given in ISO 11950 and  ISO 11949  and the 
following apply.  
3.1 
metallic c rown cap  
light gauge metal lined with cork or plastic used to close off the opening of  narrow neck bottles  and prevent 
loss of its contents  
3.2 
crown shell  
metallic component of the  crown  cap  
©RSB 2021 - All rights reserved                  2 
 3.3 
liner 
medium used to form a seal between a closure and a container  
4 Requirements  
4.1 General requirements  
4.1.1  Crown shell  
The crown shell  also known as base steel  shall be: 
a) made from Tin Free Steel (TFS) also known as Electrolytic chromium/chromium oxide -coated steel 
(ECCS) or Electrolytic Tinplate;  and  
b) have either a stone finish or matt finish ,  bright finish or silver finish . 
4.1.2  Liner  
The liner shall :  
a) be manufactured from food grade  Thermoplastic Elastomers (TPE) , PVC, PVC free with proper sealing 
ability ; 
b) be manufactured in compliance with Good Manufacturing Practice ; 
c) contain inhibitor approved for use in food products ; 
d)  be free from pits and pinholes ; 
e) have no adverse effect on the food product (e.g. through chemical reactions, leaching of liner materials or 
absorption);  
f) neither  be affected by the foodstuff packed nor altered by  the ingredients of the food  in its final form  in 
terms of its properties and protective function;  
g) not result into unacceptable changes in the organoleptic characteristics of the foo dstuff; and  
h) not be manufactured using post -consumer recycled materials . 
4.1.3  Crown cap  assembling  
4.1.3 .1 Lined  crown cap shall be fitted with the liner and shall be well-matched  with the  bottle they are 
intended to seal.  When tested in accordance with RS EAS 354, the lined crown cap  shall not leak, nor allow 
diffusion and permeation.  DRS 463 : 2021  
3                ©RSB 2021 - All rights reserved  
 4.1.3 .2 The liner shall firmly adhere to the shell so that it cannot fall or displayed f rom the crown shell  during 
storage, transportation or when the bottle is sealed.  
4.1.3 .3 The adhesive used to bind the  liner to the crown shell shall be of no n-toxic quality  
5 Specific requirements  
5.1 Crown shell /base steel  
 The crown shell  shall be made from ECCS complying with ISO 11950 or Electrolytic Tinplate complying with 
ISO 1194 9 when tested in accordance with the test method s specified therein.  
In addition to the requirements of ISO 11949 and ISO 11950, the steel base type L that is food grade shall 
comply with the chemical composition requirements given in Table 1.  Incomprehens ible  
Table—1 Chemical composition of the base steel for metallic crown caps  
S/No.  Element  Cast composition, %, max.  
 Carbon  0.13 
 Manganese  0.60 
 Phosphorus  0.020  
 Sulfur  0.03 
 Silicona,b  0.020  
 Copper  0.06 
 Nickel  0.04 
 Chromium  0.06 
 Molybdenum  0.05 
 Alumin iumC 0.10 
 Other elements, each  0.02 
a When steel produced by the silicon killed method is ordered, the silicon maximum may be increased to 0.080 %.  
b When strand cast steel produced by the alumin ium killed method is ordered or furnished, the silicon maximum may be increased to 
0.030 % when approved by the purchaser . 
c Types L may be supplied as non -killed or killed, which would respectively be produced without and with alumin ium additions.   
5.2 Liner  
When tested in accordance with Annex A  the overall migration limit of the liner constituents shall not exceed 
60 milligrams per kilogram of the simulant , equivalent to 10 milligrams of total non -volatile substances 
released into food simulant per square de cimetre of surface area of the liner .  
5.3 Moisture content  
For satisfactory assembly and to avoid excessive sweating in the lined crown caps, the initial moisture content 
in the composite cork shall be 4 -6% when tested in accordance with ISO 15512.   
©RSB 2021 - All rights reserved                  4 
 6 Dimension s of the crown caps  
Dimensions of crown caps shall be as given in Figures 1, 2, 3 and 4  
6.1 Crown cork dimension  
 
 
 
Figure 1 — Dimensions  of crown cork  
 
 
 
DRS 463 : 2021  
5                ©RSB 2021 - All rights reserved  
  
6.2 Pry off crown profiles  
 
Figure 2 — Dimensions of pry off crown caps (Profile 916)  
 
 
Figure 3 — Dimensions of pry off crown caps (Profile 923)  
 
 
©RSB 2021 - All rights reserved                  6 
 6.3 Twist off or  Universal crown profiles  
 
 
Figure 4 — Dimensions of twist off / Universal crown profiles (profile 917)  
7 Packaging and storage  
7.1 Crown caps shall be p ackaged in one of the following:  
a) strong carton boxes with biodegradable liner  for protection;  
b) one way strong bulk octabins; or  
c) one way heat treated and fumigative pallets.  
7.3 All packaging materials shall be recyclable.  
7.4 Crown caps shall be packaged, stored and transported in a clean and dry environment, away from 
direct sunlight and at temperatures not exceeding more than 40 °C.  
8 Marking  
The bulk package of the crown caps shall be marked with the following information:  
a) name and /or trade mark of the manufacturer and physical address;  
b) sealing force for twist off crowns;  
DRS 463 : 2021  
7                ©RSB 2021 - All rights reserved  
 c) opening torque for twist off crowns;  
d) shelf life;  
e) batch number ; 
f) storage instructions; and 
g) Number of pieces in a box and number of boxes per bulk package . 
9 Sampling  
Sampling shall be done in accordance with RS ISO 2859 -1. 
  
©RSB 2021 - All rights reserved                  8 
 Annex  A 
(normative ) 
Determination of overall migration of constituents of plastics materials 
and articles intended to come in contact with foodstuffs - Method of 
analysis  
A.1 Types of simulants  
The determination of migration in simulants is to be carried ou t using the simulants laid down:  
a) Simulant ‘A’ - distilled water or water of equivalent quality.  
b) Simulant ‘B’ - 3 percent acetic acid (w/v) in aqueous solution (using the simulant ‘A’)  
c) Simulant ‘C1 - 10 percent ‘ethanol (v/v) in aqueous solution for foodstuffs aqueous solution for foodstuffs 
having alcohol less than 10 percent (v/r)) (using the simulant ‘A’).  
d) Simulant ‘C2’ - - 50 percent ethanol (v/v) in aqueous solution for foodstuffs having alcoho l more than 10 
percent and less than 50 percent (r/v) (using the simulant ‘A’).  
e) Simulant ‘D’ -n-heptane - shall be freshly distilled before use.  
f) Simulant ‘E’ -Rectified olive oil or mixture of synthetic triglycerides or sunflower oil.  
NOTE  This simulant ‘E’  suggested by EEC for fatty foods need not be considered at present as the methodology of 
estimation is not yet developed.  
A.2 Selection of standard test conditions and simulants for different foods tuffs  
4.1 The choice of simulating solvents and test  condition s (time -temperature) depends on the type of  foodtuff 
and its condition of use. Food  products have been classified into seven major  groups suitable simulants to be 
used for different types of foods as per Table 1.  
Table A1—Classification of Foods and Selec tion of simulant  
S/N Type 
of 
food   Description  Examples  Simulant  
i.  I Aqueous, non -acidic foods 
without fat (pH > 5)  Honey, mineral water, sugar syrups molasses, 
skimmed milk, rusgulla, infusions, murabba, yeast, 
paste etc yeast paste etc  ‘A’ 
 
ii.  II Aqueous. acidic foods without 
fat (pH ≤ 5 5 ) 
 Fruit juices, squashes, fruit chunks or puree or 
paste, vinegar, jams, jellies, carbonated beverages. 
lemonade, processed vegetables, rennet, 
preparations of soups, broths, sauces, RTS 
beverages etc  ‘B’ DRS 463 : 2021  
9                ©RSB 2021 - All rights reserved  
 iii.  III Alcoholic 
beverages:  i)Alcohol 
concentration 
less than 10 
percent  Beer and some pharmaceuticals syrups  ‘C1” 
 ii)Alcohol 
concentration 
above 10 percent  Wine, brandy, whiskey, arrack and other alcoholic 
drinks  ‘C2’ 
iv.  IV Oils. fats and processed dry 
foods with surface fat or 
volatile oil  Vegetable oils, ghee, cocoa butter, lard,  
biscuits, spice powder, snacks and savoury. 
chocolate,  
caramels, malted foods, egg powder, tea, coffee 
powder  
confectionery, fried and roasted nuts etc  ‘D’ 
v.  V Nonacidic foods (pH >  5) or 
high fat and having high 
moisture content  Butter, bread, pastry shreekand  with low cakes, 
milk based sweets, ice -cream, moist and fatty 
confectionery products  A and D’  
vi.  VI Acidic foods (pH ˂ 5) or high 
fat and having high moisture 
content  Pickles,  ketchup, cheese, with low curd, fresh and 
processed meat and fish products, sauces having 
fat, frozen foods, mayonnaise etc  ‘B and D’  
vii.  VII Dry processed foods without 
fat Cereals and pulses, dehydrated vegetable and 
fruits, dried yeast. corn flakes, salt , sugar, milled 
products, barley powder, oats, vermicelli, spaghetti 
etc No end test  
 
4.2 Table 2 lists th e simulants and test conditions (time -temperature) for extractability studies to be  carried 
out as above depending on the type of food and  conditions  of use.  
Table 2—Simulating solvents for different types of food,  temperature  and time conditions  
S/No.  Conditions of use  Type 
of 
food  Water (time - 
temperature )  3 % Acetic 
acid  
(time-
temperature ) 10% alcohol  
(time- 
temperature ) 50% alcohol  
(time - 
tempe rature )  n-Heptane  
i.  High temperature  
heat sterilized 
(Retorting ) I, II, 
IV, V 
and VI 121°C , 2h 121°C , 2h - - 66°C for 2 h  
ii.  Hot filled or 
pasteurized above 
66°C, 100°C  I, II, 
IV, V 
and VI  100°C, 2h  100°C, 2h  - - 49°C for  30 
minutes  
iii.  Hot filled or 
pasteurized below 
66°C  I to VI  700C, 2h  700C, 2h  700C, 2h  700C, 2h  38°C for 30 
minutes  
iv.  Room temperature 
filled and stored (no 
thermal treatment in 
container) and also in 
refrigerated and 
frozen condition  do 400C, 10 days  400C, 10 
days  400C, 10 
days  400C, 10 days  do 
NOTES   
©RSB 2021 - All rights reserved                  10 
 1 Heptane simulant not to be used on wax lined containers.  
2 Heptane e xtractivity results must be divided by a factor of five in arriving at the extractivity of a food product  
A.3 Selection of Sample  
At least triplicate samples each consisting of a number of closures/sealing gaskets/liners with the lids 
exposing about 100 cm2 contact area (or ten lids) per  replicate in each representing a lot or batch shall be  
selected.  
A.4  Procedure  
Smallest size glass bottles/jars actually being intend ed for use with closures can be used as containers to 
contain the simulant. Fill the glass container to their nominal capacity or 100 ml, whichever is lower with 
simulant preheated to test temperature and closed tight with the closures/lids lined with the test specimen.  
Place the closed containers upside down (to ensure the contact of the closures with the simulant) in an oven 
maintained at test temperature. After the exposure to the stipulated time, the closure from the containers are 
opened and the conten ts from each replicate is pooled together in a glass beaker along with the washings of 
the exposed closures with small amount of fresh simulant. Blank shall also be carried out without the sample.  
A.5  Determination of Amount of Extractive  
Evaporate/distill th e contents in Pyrex beaker to about 50 -60 ml and transfer into a clean tared stainless steel 
dish along with 3 washings of Pyrex beaker with small quantity of fresh simulant and further evaporate the 
concentrate in the dish to dryness in an oven at 100 + 5 °C. Cool the dish with extractive in a desiccator  for 30 
minutes and weigh to nearest 0.1 mg till constant weight of residue is obtained. Calculate the extractives in 
mg/dm* and mg/kg or mg/l or ppm of the foodstuff with respect to the capacity of containe r/pouch to be used. 
Blank shall also be carried out without the sample.  
 
Calculate the amount of extractive in ppm for the  particular size of contain er being tested.  
Amount of extractive (Ex) = 𝑀
𝑉x1000 mg/kg or mg/l    
                          Or       Ex= 𝑀
𝐴x100 mg/dm2  
Where  
M = mass of residue in mg minus blank value,  
A= surface area in cm2 exposed in each replicate  
and 
V = volume of the container in ml in a replicate in actual use.  DRS 463 : 2021  
11                ©RSB 2021 - All rights reserved  
 Bibliography  
[1] ASTM  A 623 – 16 Standard Specification for Tin  Mill Products, General Requirements  
[2] US 1659:2016  Materials in Contact with Food — Requirements for Packaging materials  
[3] IS 9845 (1998): Determination of overall migration of constituents of plastics materials and articles 
intended to come in contact with foodstuffs – method of analysis  
 
 
 DRS 463: 2021  
 
Price based on 10 pages  
©RSB 2021 - All right s reserved