SIST EN ISO 10684:2004

SLOVENSKI STANDARD
SIST EN ISO 10684:2004
01-november-2004
9H]QLHOHPHQWL=YURþLPSRFLQNDQMHPQDQHVHQHSUHYOHNH,62
Fasteners - Hot dip galvanized coatings (ISO 10684:2004)
Verbindungselemente - Feuerverzinkung (ISO 10684:2004)
Éléments de fixation - Revetements de galvanisation a chaud (ISO 10684:2004)
Ta slovenski standard je istoveten z: EN ISO 10684:2004
ICS:
21.060.01 Vezni elementi na splošno Fasteners in general
25.220.40 Kovinske prevleke Metallic coatings
SIST EN ISO 10684:2004 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN ISO 10684:2004

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SIST EN ISO 10684:2004
EUROPEAN STANDARD
EN ISO 10684
NORME EUROPÉENNE
EUROPÄISCHE NORM
July 2004
ICS 25.220.40; 21.060.01
English version
Fasteners - Hot dip galvanized coatings (ISO 10684:2004)
Éléments de fixation - Revêtements de galvanisation à Verbindungselemente - Feuerverzinkung (ISO 10684:2004)
chaud (ISO 10684:2004)
This European Standard was approved by CEN on 17 June 2004.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national
standards may be obtained on application to the Central Secretariat or to any CEN member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the official
versions.
CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France,
Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia,
Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36  B-1050 Brussels
© 2004 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 10684:2004: E
worldwide for CEN national Members.

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SIST EN ISO 10684:2004

EN ISO 10684:2004 (E)





Foreword


This document (EN ISO 10684:2004) has been prepared by Technical Committee ISO/TC 2
"Fasteners" in collaboration with Technical Committee CEN/TC 185 "Threaded and non-
threaded mechanical fasteners and accessories", the secretariat of which is held by DIN.

This European Standard shall be given the status of a national standard, either by publication of
an identical text or by endorsement, at the latest by January 2005, and conflicting national
standards shall be withdrawn at the latest by January 2005.

According to the CEN/CENELEC Internal Regulations, the national standards organizations of
the following countries are bound to implement this European Standard: Austria, Belgium,
Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary,
Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland,
Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.


Endorsement notice

The text of ISO 10684:2004 has been approved by CEN as EN ISO 10684:2004 without any
modifications.

2

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SIST EN ISO 10684:2004


INTERNATIONAL ISO
STANDARD 10684
First edition
2004-07-15


Fasteners — Hot dip galvanized coatings
Éléments de fixation — Revêtements de galvanisation à chaud




Reference number
ISO 10684:2004(E)
©
ISO 2004

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SIST EN ISO 10684:2004
ISO 10684:2004(E)
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©  ISO 2004
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ii © ISO 2004 – All rights reserved

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SIST EN ISO 10684:2004
ISO 10684:2004(E)
Contents Page
Foreword. iv
1 Scope. 1
2 Normative references. 1
3 Terms and definitions. 2
4 Materials. 3
4.1 Raw material of parts. 3
4.2 Zinc. 3
5 Hot dip galvanizing procedures and precautions . 3
5.1 Stress relief. 3
5.2 Cleaning and pickling. 3
5.3 Baking. 3
5.4 Fluxing. 3
5.5 Hot dip galvanizing . 3
5.6 Spinning and quenching . 4
5.7 Special requirements for nuts . 4
5.8 Post-treatment. 4
6 Requirements on thread tolerances and additional marking . 4
6.1 General. 4
6.2 Requirements and precautions in assembling hot dip galvanized threaded fasteners . 4
6.3 Special requirements for marking when supplying fasteners in sealed containers. 8
7 Mechanical properties of nuts tapped oversize and undersize threaded bolts, screws and
studs. 8
8 Coating requirements. 8
8.1 Appearance of zinc coating . 8
8.2 Considerations for hot dip galvanized washers . 8
8.3 Zinc coating thickness . 8
8.4 Adhesion of zinc coating. 8
9 Lubrication. 9
10 Ordering requirements. 9
11 Designation. 9
Annex A (normative) Special requirements for bolts, screws and nuts with thread sizes M8 and
M10 . 11
Annex B (normative) Limits of sizes for hot dip galvanized internal and external screw thread M8 . 13
Annex C (informative) Calculation of minimum ultimate tensile loads and proof loads for bolts
and screws M8 and M10 with threads undersized to tolerance class 6az . 15
Annex D (informative) Surface areas of bolts, screws and nuts . 16
Annex E (normative) Adherence of hot-dip galvanized coating. 19
Annex F (informative) Strength of hot dip galvanized bolt or screw and nut assemblies. 20

© ISO 2004 – All rights reserved iii

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SIST EN ISO 10684:2004
ISO 10684:2004(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 10684 was prepared by Technical Committee ISO/TC 2, Fasteners, Subcommittee SC 1, Mechanical
properties of fasteners.

iv © ISO 2004 – All rights reserved

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SIST EN ISO 10684:2004
INTERNATIONAL STANDARD ISO 10684:2004(E)

Fasteners — Hot dip galvanized coatings
1 Scope
This International Standard specifies material, process, dimensional and some performance requirements for
hot dip spun galvanized coatings applied to coarse threaded steel fasteners from M8 up to and including M64
and for property classes up to and including 10.9 for bolts, screws and studs and 12 for nuts. It is not
recommended to hot dip galvanize threaded fasteners in diameters smaller than M8 and/or with pitches below
1,25 mm.
NOTE Attention is drawn to the fact that the proof loads and stresses under proof load of oversize tapped nuts with
threads M8 and M10 and the ultimate tensile loads and proof loads of undersize threaded bolts and screws with threads
M8 and M10 are reduced as compared to the values specified in ISO 898-2 and ISO 898-1 respectively and are specified
in Annex A.
It primarily concerns the spun hot dip galvanizing of threaded steel fasteners, but it may also be applied to
other threaded steel parts.
The specifications given in this International Standard may also be applied to non-threaded steel parts such
as washers.
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.
ISO 898-1, Mechanical properties of fasteners made of carbon steel and alloy steel — Part 1: Bolts, screws
and studs
ISO 898-2, Mechanical properties of fasteners — Part 2: Nuts with specified proof load values — Coarse
thread
ISO 965-1, ISO general purpose metric screw threads — Tolerances — Part 1: Principles and basic data
ISO 965-2, ISO general purpose metric screw threads — Tolerances — Part 2: Limits of sizes for general
purpose external and internal screw threads — Medium quality
ISO 965-3, ISO general purpose metric screw threads — Tolerances — Part 3: Deviations for constructional
screw threads
ISO 965-4, ISO general purpose metric screw threads — Tolerances — Part 4: Limits of sizes for hot-dip
galvanized external screw threads to mate with internal screw threads tapped with tolerance position H or G
after galvanizing
ISO 965-5, ISO general purpose metric screw threads — Tolerances — Part 5: Limits of sizes for internal
screw threads to mate with hot-dip galvanized external screw threads with maximum size of tolerance
position h before galvanizing
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SIST EN ISO 10684:2004
ISO 10684:2004(E)
ISO 1460, Metallic coatings — Hot dip galvanized coatings on ferrous materials — Gravimetric determination
of the mass per unit area
ISO 1461, Hot dip galvanized coatings on fabricated iron and steel articles — Specifications and test methods
ISO 2064, Metallic and other inorganic coatings — Definitions and conventions concerning the measurement
of thickness
ISO 2178, Non-magnetic coatings on magnetic substrates — Measurement of coating thickness — Magnetic
method
ISO 8991, Designation system for fasteners
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 2064 (in particular, the definitions of
significant surface, measuring area, local thickness, minimum local thickness and average thickness) and the
following apply.
3.1
batch
quantity of identical parts cleaned, pickled, fluxed and galvanized together at one time in a galvanizing basket
3.2
production lot
batches of parts originating from the same manufacturing lot, processed continuously through cleaning,
pickling, fluxing, dipping in molten zinc and spun in a centrifuge without any change in temperature and
concentration of the constituents of the process
3.3
batch average thickness
calculated average thickness of a coating as if it was uniformly distributed over the surface of the parts of the
batch
3.4
baking
process of heating parts for a definite time at a given temperature in order to minimize the risk of hydrogen
embrittlement
3.5
stress relief
process of heating parts for a definite time at a given temperature in order to relieve stress induced by work
hardening
3.6
hot dip galvanizing of fasteners
process whereby steel fasteners are zinc coated by immersion in a bath of molten zinc, resulting in the
formation of a zinc-iron alloy coating or a zinc-iron alloy coating plus a zinc coating at the surface of the
fastener
NOTE This process involves the removal of excess zinc by spinning the parts in a centrifuge or by an equivalent
method.
2 © ISO 2004 – All rights reserved

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SIST EN ISO 10684:2004
ISO 10684:2004(E)
4 Materials
4.1 Raw material of parts
4.1.1 Chemical composition
Materials as included in ISO 898-1 and ISO 898-2 are suitable for hot dip galvanizing except if the total
content of phosphorus and silicon is between 0,03 % and 0,13 %, in which case high temperature galvanizing
(530 °C to 560 °C) is recommended.
4.1.2 Surface condition
The surface of the fastener, before immersion in the molten zinc, shall be clean and free from all contaminants
that would adversely effect the galvanizing.
4.2 Zinc
The zinc used for this process shall be in accordance with ISO 1461.
5 Hot dip galvanizing procedures and precautions
5.1 Stress relief
Fasteners subjected to severe work hardening may require stress relief before acid cleaning and hot dip
galvanizing.
5.2 Cleaning and pickling
Parts shall be cleaned. During the cleaning process, hydrogen could be absorbed into the steel. The hydrogen
may not effuse completely in the galvanizing bath and consequently, may lead to brittle failure. Unless
otherwise agreed, parts heat treated or work hardened to a hardness of W 320 HV shall be cleaned using an
inhibited acid, alkaline or mechanical process. Immersion time in the inhibited acid depends on the
as-received surface condition and should be of minimum duration.
NOTE An inhibited acid is an acid to which a suitable inhibitor has been added to reduce corrosive attack on the steel
and absorption of hydrogen.
5.3 Baking
If baking is carried out, it shall be carried out prior to surface activation.
5.4 Fluxing
Parts shall be surface activated, and dried if necessary.
5.5 Hot dip galvanizing
Normal temperature galvanizing is carried out at a bath temperature of 455 °C to 480 °C. High temperature
galvanizing is used to produce a smoother and thinner coating and is carried out at a bath temperature of
530 °C to 560 °C. The finish obtained using the high temperature process is dull. In order to avoid micro-
cracks, bolts, screws and studs of property class 10.9 in sizes M27 and above, shall not be high temperature
galvanized.
Galvanizing shall not be carried out at bath temperatures between 480 °C and 530 °C.
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SIST EN ISO 10684:2004
ISO 10684:2004(E)
5.6 Spinning and quenching
Parts shall be spun immediately following removal from the galvanizing bath and quenched in water or air
cooled depending on size consideration.
5.7 Special requirements for nuts
Nut threads and other internal threads shall be tapped after hot dip galvanizing. Retapping shall not be
permitted.
5.8 Post-treatment
Most galvanized parts do not require any post treatment. When required by the purchaser, treatments such as
chromating or phosphating may be applied to reduce the possibility of wet storage staining (white corrosion) or
to assist subsequent painting.
6 Requirements on thread tolerances and additional marking
6.1 General
Dimensional limits for ISO metric screw threads M10 to M64 before and after coating are specified in
ISO 965-1 to ISO 965-5. All other dimensions and tolerances of fasteners apply before hot dip galvanizing.
Dimensional limits for internal and external screw threads M8 with thread tolerances 6AX and 6AZ for internal
threads and 6az for external threads are specified in Annex B.
NOTE It is not possible to check the thread tolerance of a hot dip galvanized part by stripping the coating and
gauging the thread thereafter, since some steel is dissolved from the part during the galvanizing process.
6.2 Requirements and precautions in assembling hot dip galvanized threaded fasteners
6.2.1 General
This clause applies only to parts with thread tolerances in accordance with ISO 965-1 to ISO 965-5 and with
marking according to the marking requirements for fasteners as given in ISO 898-1 and ISO 898-2. The
marking specified in 6.2.2 and 6.2.3 shall be carried out in addition to the marking according to ISO 898-1 and
ISO 898-2.
The application of zinc coating by the hot dip process results in the deposition of a heavy coating thickness of
zinc (always in excess of 40 µm). Hence, it is necessary to manufacture screw threads to special limits in
order to accommodate such heavy coatings.
There are two different methods provided for, which give the necessary fundamental deviations (clearances)
for the zinc layer applied to fasteners by hot dip galvanizing.
The first method (see 6.2.2) consists of using nuts tapped oversize to tolerance class 6AZ or 6AX after coating,
to mate with bolts or screws manufactured with screw threads to tolerance position g or h before coating.
The second method (see 6.2.3) consists of using bolts or screws manufactured with threads undersized to
tolerance class 6az before coating, to mate with nuts tapped to tolerance position H or G after coating.
Nuts tapped oversize (marked with Z or X) shall never be mated with bolts or screws with undersized
threads (marked with U), because such combinations create a high probability of thread stripping.
Assembling hot dip galvanized nuts tapped to tolerance position H or G after coating with hot dip galvanized
bolts or screws manufactured with threads to tolerance position g or h before coating results in thread
interference.
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SIST EN ISO 10684:2004
ISO 10684:2004(E)
6.2.2 Nuts tapped oversize to tolerance class 6AZ or 6AX after coating
Oversize tapping of nuts and internal threads to tolerance class 6AZ or 6AX in accordance with ISO 965-5 is
required after hot dip galvanizing when the mating bolts or screws or external threads are manufactured to
tolerance position g or h in accordance with ISO 965-1 to ISO 965-3 before hot dip galvanizing.
Nuts tapped oversize shall be marked with the letter Z immediately after the property class mark in case of
tolerance class 6AZ or with the letter X in case of tolerance class 6AX. See example in Figure 1.

Figure 1 — Example of marking of hot dip galvanized nuts tapped oversize
to tolerance position 6AZ after coating
In order to reduce the risk of interference on assembly of threads with hot dip galvanized coatings, the coating
thickness on the mating bolts or screws or external threads advisably should not exceed one quarter of the
minimum clearance of the thread combination. These values are given in Table 1 for information.

© ISO 2004 – All rights reserved 5

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SIST EN ISO 10684:2004
ISO 10684:2004(E)
6 © ISO 2004 – All rights reserved
Table 1 — Fundamental deviations and upper limits of coating thicknesses for assemblies with nuts tapped oversize
Nominal
Minimum clearance and maximum coating thickness for thread combinations
Pitch thread Fundamental deviation
(for information)
diameter
Internal External
 AZ/h AZ/g AX/h AX/g
thread thread
Maximum Maximum Maximum Maximum
Minimum Minimum Minimum Minimum
P d AZ AX h g
coating coating coating coating
clearance clearance clearance clearance
thickness thickness thickness thickness
mm mm µm µm µm µm µm µm µm µm µm µm µm µm
a a
1,25 8 0 − 28 325 81 353 88 255 64 283 71
+ 325 + 255
1,5 10 0 330 83 362 91 310 78 342 86
+ 330 + 310 − 32
1,75 12 0 335 84 369 92 365 91 399 100
+ 335 + 365 − 34
2 16 (14) + 340 + 420 0 − 38 340 85 378 95 420 105 458 115
2,5 20 (18,22) + 350 + 530 0 − 42 350 88 392 98 530 133 572 143
3 24 (27) + 360 + 640 0 − 48 360 90 408 102 640 160 688 172
3,5 30 (33) + 370 + 750 0 − 53 370 93 423 106 750 188 803 201
4 36 (39) + 380 + 860 0 − 60 380 95 440 110 860 215 920 230
4,5 42 (45) + 390 + 970 0 − 63 390 98 453 113 970 243 1 033 258
5 48 (52) + 400 + 1 080 0 − 71 400 100 471 118 1 080 270 1 151 288
5,5 56 (60) + 410 + 1 190 0 − 75 410 103 485 121 1 190 398 1 265 316
6 64 + 420 + 1 300 0 − 80 420 105 500 125 1 300 325 1 380 345
a
The fundamental deviations for AZ and AX are calculated according to the formulae given in ISO 965-5 on the basis of the thread dimensions specified in Annex B.

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SIST EN ISO 10684:2004
ISO 10684:2004(E)
6.2.3 Bolts and screws with threads undersized to tolerance class 6az before coating
Undersize threading of bolts, screws and external threads to tolerance class 6az in accordance with
ISO 965-4 is required before hot dip galvanizing, when the mating nuts or internal threads have tolerance
position G or H in accordance with ISO 965-1 to ISO 965-3 after hot dip galvanizing.
Bolts and screws with undersized threads shall be marked with the letter U immediately after the property
class mark. See example in Figure 2.

Key
1 manufacturer’s identification mark
2 property class and additional marking
Figure 2 — Example of marking of hot dip galvanized bolts and screws with threads undersized to
tolerance class 6az before coating
In order to reduce the risk of interference on assembly of threads with hot dip galvanized coatings, the coating
thickness advisably should not exceed one quarter of the minimum clearance of the thread combination.
These values are given in Table 2 for information.
Table 2 — Fundamental deviations and upper limits of coating thicknesses
for assemblies with bolts and screws with undersized threads
Nominal Minimum clearance and maximum
Pitch thread Fundamental deviation coating thickness for thread combinations
diameter (for information)
External Internal
 az/H az/G
thread thread
Maximum Maximum
Minimum Minimum
P d az H G coating coating
clearance clearance
thickness thickness
mm mm µm µm µm µm µm µm µm
a
1,25 8 − 325 0 + 28 325 81 353 88
1,5 10 − 330 0 + 32 330 83 362 91
1,75 12 − 335 0 + 34 335 84 369 92
2 16 (14) − 340 0 + 38 340 85 378 95
2,5 20 (18, 22) − 350 0 + 42 350 88 392 98
3 24 (27) − 360 0 + 48 360 90 408 102
3,5 30 (33) 0 370 93 423 106
− 370 + 53
4 36 (39) − 380 0 + 60 380 95 440 110
4,5 42 (45) 0 390 98 453 113
− 390 + 63
5 48 (52) 0 400 100 471 118
− 400 + 71
5,5 56 (60) 0 410 103 485 121
− 410 + 75
6 64 0 420 105 500 125
− 420 + 80
a
The fundamental deviation for az is calculated according to the formula given in ISO 965-4 on the basis of the thread dimensions
specified in Annex B.
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SIST EN ISO 10684:2004
ISO 10684:2004(E)
6.3 Special requirements for marking when supplying fasteners in sealed containers
If hot dip galvanized bolts or screws and mating nuts are packed together and supplied in the manufacturer’s
sealed container, the additional marking of the bolts, screws or nuts as described in 6.2.2 and 6.2.3 is not
mandatory. The label on each sealed container shall indicate the additional marking as required in 6.2.2 and
6.2.3.
Additional marking of products or labelling of containers as described in 6.2.2 and 6.2.3 is not mandatory for
fasteners with a special marking related to a product standard which specifies the thread tolerance for hot dip
galvanized bolts, screws, studs or nuts and, therefore, does not allow the manufacturer to choose the thread
tolerance.
7 Mechanical properties of nuts tapped oversize and undersize threaded bolts,
screws and studs
For bolts, screws, studs and nuts W M12, the requirements of ISO 898-1 and ISO 898-2 shall be met after hot
dip galvanizing. For the sizes M8 and M10, proof loads and stresses under proof loads for nuts and ultimate
tensile loads and proof loads for bolts, screws and studs are specified in Annex A.
8 Coating requirements
8.1 Appearance of zinc coating
The hot dip galvanized parts shall be free from uncoated areas, blisters, flux deposits, black spots, dross
inclusions and other defects that would impair the intended use of the parts. Dull appearance shall not
constitute grounds for rejecting parts.
8.2 Considerations for hot dip galvanized washers
Hot dip galvanized washers tend to bond to each other and suitable acceptance criteria should be agreed
upon at the time of ordering.
8.3 Zinc coating thickness
The local coating thickness shall be a minimum of 40 µm and the batch average coating thickness shall be a
minimum of 50 µm. The measurement of the local coating thickness shall be made on measuring areas as
shown in Figure 3.
Measurement of the local coating thickness shall be conducted by the magnetic method in accordance with
ISO 2178 on every producti
...