ASTM A630-16a(2024)
(Test Method)Standard Test Methods for Determination of Tin Coating Weights for Electrolytic Tin Plate
Standard Test Methods for Determination of Tin Coating Weights for Electrolytic Tin Plate
SIGNIFICANCE AND USE
20.1 This test method covers determination of the total tin in the sample tested and does not apportion the tin to one or the other side of the test specimen. The calculations appearing in Section 27 assume uniform distribution of tin over the two surfaces.
20.2 This test method does not differentiate between free tin on the tinplate surface, tin combined with iron in the intermediate alloy layer, or tin alloyed with the steel as a residual tramp element.
SCOPE
1.1 These test methods include four methods for the determination of tin coating weights for electrolytic tin plate as follows:
Test Method
Sections
A—Bendix Test Method
3 to 9
B—Constant-Current, Electrolytic Test Method (Referee Method)
10 to 17
C—Sellar's Test Method
18 to 27
D—Titration Test Method
28 to 36
1.2 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
General Information
Relations
Standards Content (Sample)
This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: A630 − 16a (Reapproved 2024)
Standard Test Methods for
Determination of Tin Coating Weights for Electrolytic Tin
Plate
This standard is issued under the fixed designation A630; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the U.S. Department of Defense.
INTRODUCTION
Four test methods for determination of tin coating weights are described. These are typical methods
and represent those most commonly used in the tin plate industry. Publication of these test methods
is not intended to preclude the use of any other methods such as X-ray fluorescence measurement
systems for control purposes by the consumer or supplier. However, in case of dispute, the referee
method is to be used to determine conformance to Specification A624/A624M and Specification
A626/A626M.
Sampling procedures for tin coating-weight testing and applicable standards for the specific class
designation are outlined in Specification A624/A624M and Specification A626/A626M.
1. Scope* 2. Referenced Documents
1.1 These test methods include four methods for the deter- 2.1 ASTM Standards:
mination of tin coating weights for electrolytic tin plate as
A624/A624M Specification for Tin Mill Products, Electro-
follows: lytic Tin Plate, Single Reduced
A626/A626M Specification for Tin Mill Products, Electro-
Test Method Sections
A—Bendix Test Method 3 to 9
lytic Tin Plate, Double Reduced
B—Constant-Current, Electrolytic Test Method (Referee Method) 10 to 17
D1125 Test Methods for Electrical Conductivity and Resis-
C—Sellar’s Test Method 18 to 27
tivity of Water
D—Titration Test Method 28 to 36
METHOD A—DETERMINATION OF THE TIN
1.2 The values stated in inch-pound units are to be regarded
COATING WEIGHTS BY THE BENDIX TEST
as standard. The values given in parentheses are mathematical
METHOD
conversions to SI units that are provided for information only
and are not considered standard.
3. Scope
1.3 This standard does not purport to address all of the
3.1 This test method covers the determination of tin coating
safety concerns, if any, associated with its use. It is the
weights on steel plate.
responsibility of the user of this standard to establish appro-
priate safety, health, and environmental practices and deter-
4. Summary of Test Method
mine the applicability of regulatory limitations prior to use.
1.4 This international standard was developed in accor-
4.1 The procedure involves dissolution of tin from a tin
dance with internationally recognized principles on standard-
plate anode in a dilute hydrochloric acid solution containing a
ization established in the Decision on Principles for the
measured excess of standard potassium iodate-potassium io-
Development of International Standards, Guides and Recom-
dide solution. Excess iodine from the iodate-iodide solution is
mendations issued by the World Trade Organization Technical
back titrated with standard sodium thiosulfate using a starch
Barriers to Trade (TBT) Committee.
indicator.
These test methods are under the jurisdiction of ASTM Committee A01 on
Steel, Stainless Steel and Related Alloys and are the direct responsibility of
Subcommittee A01.20 on Tin Mill Products. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved March 1, 2024. Published March 2024. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
ɛ1
approved in 1968. Last previous edition approved in 2016 as A630 – 16a . DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/A0630-16AR24. the ASTM website.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
A630 − 16a (2024)
5. Apparatus the flask to a carbon dioxide (CO ) system and displace the air
in the flask with CO . While continuing the flow of CO , heat
2 2
5.1 The detinning cell consists essentially of two cathodes
the flask but do not boil violently. After the tin has dissolved
of carbon rod, the sample that serves as an anode, and a beaker
add 0.5 g of antimony and 2 g of high-purity aluminum. Heat
of dilute hydrochloric acid electrolyte. The carbon rods (6 by
until the aluminum is completely dissolved and digest for an
0.25 in. or 152 by 6.35 mm, encased in porous porcelain
additional 10 min. Cool the flask to room temperature in
thimbles) are suspended from a suitable frame about 1 in.
running water while maintaining an atmosphere of CO .
(25 mm) apart. A small glass-enclosed magnet is attached to
Disconnect from the CO system and titrate with the KIO -KI
2 3
the frame in such a manner that it will hold the sample
solution using starch as an indicator. Calculate the tin titer, T,
suspended midway between the two cathodes. A movable
as follows:
platform permits the beaker of electrolyte to be brought up
around the assembly so that the sample will be completely T 5 A/B
immersed.
where:
5.2 A source of direct current that can be regulated to supply
A = tin used (0.2700 g),
up to 3 A at 3 to 5 V through the deplater is required.
B = KIO -KI solution used for titration, mL, and
T = tin titer for above KIO -KI solution, (grams of tin/mL),
5.3 Although regular laboratory glassware can be used, it is 3
2 2
T = 17.28 = lb/base box (bb)/mL, for a 4-in. (25.81-cm )
advisable to use automatic dispensing pipets or burets, a
sample.
motor-driven stirrer for titrations, and a timing switch when
large numbers of determinations are to be made.
6.5 Sodium Thiosulfate, Standard Solution (for coatings
over 0.50 lb/bb)—Dissolve 15.11 g of Na S O ·5 H O and 1.11
5.4 Precautions—The apparatus must be kept in continuous
2 2 3 2
g of NaOH in 1 litre of distilled water in a light-proof bottle.
operation to prevent iron in the solution adhering to the porous
Allow this solution to age for 72 h, remix, and standardize as
cells from oxidizing and subsequently liberating iodine from
follows: Connect the bottle to the Bendix apparatus and titrate
the potassium iodate-potassium iodide solution. If the instru-
20 mL of the standardized KIO -KI solution with the thiosul-
ment has been idle for some time, it is necessary to remove the 3
fate solution using the same procedure as is used for making
ferric iron by running a disk of tinplate through the regular
weight of coating determinations, but ignore the stripping unit.
procedure before test samples are run.
The tin equivalent of the Na S O solution in pounds per base
2 2 3
box is equal to: 20/A × T × 17.28, where A = millilitres of
6. Reagents
sodium thiosulfate solution used in titrating 20 mL of standard
6.1 Purity of Reagents—Reagent grade chemicals shall be
KIO -KI solution. A chart can be prepared showing lb/bb/mL
used in all tests. Unless otherwise indicated, it is intended that
of thiosulfate.
all reagents shall conform to the specifications of the Commit-
tee on Analytical Reagents of the American Chemical Society 6.6 Sodium Thiosulfate, Standard Solution (for coatings
where such specifications are available. Other grades may be
0.50 lb/bb and under)—Dissolve 6.57 g of Na S O ·5 H O and
2 2 3 2
used, provided it is first ascertained that the reagent is of 2.78 g of NaOH in 1 litre of distilled water in a light-proof
sufficiently high purity to permit its use without lessening the
bottle. Larger quantities in the same proportions may be
accuracy of the determination. prepared if desired. Allow that solution to age for 72 h, remix,
and standardize by the same procedure used for the stronger
6.2 Water—Deionized or distilled water having a volume
Na S O solution but use only 10 mL of potassium iodate-
2 2 3
resistivity greater than 1 MΩ·cm at 25 °C as determined by
potassium iodide solution.
Nonreferee Method of Test Methods D1125.
6.7 Starch Solution—Heat 200 mL of distilled water to
6.3 Hydrochloric Acid (1.7 to 2.0 N)—Add 1 part of
boiling in a Florence flask and slowly add 2.5 g of soluble
concentrated hydrochloric acid (HCl, sp gr 1.19, 36.5 to
starch paste while the solution is agitated. Add the hot starch
38.0 %) to 5 parts of water and mix well.
solution to 500 mL of distilled water containing 2.5 g of
6.4 Potassium Iodate-Potassium Iodide, Standard Solution
NaOH. Dilute to 1 L and thoroughly mix.
(0.0975 N)—Dissolve 3.48 g of KIO , 21.74 g of KI, and 1.21
g of NaOH in 1 L of distilled water. Standardize as follows:
7. Test Sample
Transfer 0.2700 g of National Bureau of Standards tin to a
7.1 Tin plate samples for coating weight determinations are
500-mL Erlenmeyer flask. Add 200 mL of HCl (1+1). Connect
obtained by stamping disks 2.257 6 0.001 in. (57.33 6 0.02
2 2
mm) in diameter which is equivalent to 4 in. (25.81 cm ) of
2 2
area (8 in. (52 cm ) of surface area). Recommended methods
Complete details and drawings of the apparatus are contained in U. S. Patent
No. 2,455,726 entitled “Method for Electrolytic Stripping and Determination of
of obtaining representative samples are described in the Tin
Plating Metals.” A suitable commercial supplier of the apparatus has been found to
Mill Products sections of the American Iron and Steel Insti-
be the Wilkens-Anderson Company of Chicago.
4 tute’s Steel Products Manual.
Reagent Chemicals, American Chemical Society Specifications, American
Chemical Society, Washington, DC. For suggestions on the testing of reagents not
listed by the American Chemical Society, see Analar Standards for Laboratory
Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
and National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville, Available from American Iron and Steel Institute (AISI), 1140 Connecticut
MD. Ave., NW, Suite 705, Washington, DC 20036, http://www.steel.org.
A630 − 16a (2024)
8. Procedure tin coating which is present as free tin and that part which is
present in the alloyed form.
8.1 Make required electrical connections.
8.2 Add HCl (1+1) to the porous tubes containing the
11. Summary of Test Method
carbon cathodes.
11.1 In this test method, the tin is stripped from a sample of
8.3 Suspend the sample disk of tin plate from the magnetic
tin-plate anodically at constant current in an electrolyte of the
holder.
hydrochloric acid. The potential difference developed between
the sample and a reference electrode is plotted against time on
NOTE 1—If it is desired to strip on one side only, mask the opposite side
a strip chart recorder or an electric digital readout. The time
and reduce the current to half its normal value. If a heavy oxide film has
developed on the tin plate during storage, the plate must be cathodically
required for stripping the free tin and alloyed tin, respectively,
cleaned prior to testing.
are read from the resulting chart (see Fig. 1) or a digital
8.4 Place a measured quantity of standardized KIO -KI readout. Since the stripping current has been preset, the free-tin
and alloy-tin coating weights are calculated by employing
solution into a 400-mL beaker (see 8.10). Simultaneously add
Faraday’s law of electrolysis.
250 mL of dilute HCl and mix thoroughly.
8.5 Raise the beaker so that the sample and porous cells are
12. Calibration and Standardization
immersed.
12.1 Determine the weight loss of pure tin specimens
8.6 Turn on d-c current and adjust to give 0.5 A/in. of
electrolyzed for a given time interval, expressing the results as
sample.
milligrams or pounds of tin per base box per second.
8.7 Time for complete removal of tin (see 8.10).
12.2 The test specimen should be a 4-in. disk of pure tin
8.8 Remove the beaker and add approximately 5 mL of
approximately 0.20 in. (5.1 mm) thick.
starch indicator solution.
12.3 The milliammeter should be frequently checked using
8.9 Titrate with standardized Na S O solution to the dis-
a precision milliammeter.
2 2 3
appearance of the blue color.
13. Available Constant Current Procedures
8.10 The stripping times and amounts of KIO -KI solution
13.1 There are three commercially available constant
to use are as follows:
current, electrolytic units that are in common use. Either of the
Amount of
Stripping KIO -KI following, or equivalent equipment, can be used as an accept-
Product Time, s Solution, mL
able referee method:
Electrolytic 100 90 20
13.1.1 Willey & Kunze Coulometric Test Method—Supplier
Electrolytic 75 75 20
Electrolytic 50 60 10
will provide set up, start up and running procedures.
Electrolytic 25 60 10
13.1.2 The Stannomatic Test Method—Supplier will provide
Electrolytic 10 45 10
set up, start up and running procedures.
Stripping time should not be longer than is required to
13.1.3 The Donart Test Method—Supplier will provide
remove all of the tin. Results will be high by approximately 9
setup, start, and running procedures.
0.01 lb/bb for each minute of over-stripping.
14. Willey & Kunze Coulometric Test Method
9. Reproducibility of Results
14.1 In this test method, the tin is electrolytically removed
9.1 Arbitrary maximum spreads in intermill check tests 2 2
from a 4 in. (25.807 cm ) circular sample of tinplate anodi-
show the reproducibility of test results by the Bendix Method
cally at constant current in an electrolyte of 1.0 N hydrochloric
to be as follows: 60.02 lb/bb for 0.25–lb coatings, 60.03 lb/bb
acid. The potential difference developed between the sample
for 0.75-lb coatings, and 60.04 lb/bb for 1.25-lb coatings. Data
and a glass calomel reference electrode is plotted against time
have not been developed for 0.10-lb coatings.
on a strip chart recorder. The time required for stripping the
free tin and alloy tin, respectively are read from the resulting
METHOD B—DETERMINATION OF THE TIN
chart (see Fig. 1) or on an electronic digital readout. Since the
COATING WEIGHTS BY THE CONSTANT
stripping current is constant and preset, the free tin and alloy
CURRENT, ELECTROLYTIC METHOD (REFEREE
tin coating weights are calculated by employing Faraday’s law
METHOD)
of electrolysis.
10. Scope
14.2 Significance and Use:
14.2.1 The amount of tin coating is directly associated with
10.1 This test method may be used to determine not only
the economics of producing tinplate and the performance of the
the total tin coating weight but also to determine that part of the
container or part for which such plate is use
...
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