RESOURCE GUIDE

METRIC DIMENSION SPECIFICATIONS

The difference
between JIS,
DIN, ASME, & EN
Metric Hex Flange
Screws & Nuts 20239EMP
 RESOURCE GUIDE

Understanding Metric Hex

Flange Dimensional Standards
Understanding the dimensional standards
that metric sizes of hex flange screws and hex "Is there a dimensional
standard that you
flange nuts can be made to is not as simple as
the dimensional standards to which we make
our inch (also called Imperial) sizes of flange
products. When we are dealing with inch size
product (ex: 5/8 - 11 x 1 1/2 Hex Flange Bolt,
need these to meet?"
Grade 8, Plain) we can be confident that our
customer is looking for a hex flange screw A couple of things to remember when
that is made to the dimensional standard dealing with metric flange bolts and nuts are:
of ASME B18.2.1 (also listed in IFI-111).
The threads are the same no matter which
When you are dealing with metric products,
standards organization the parts are made
it becomes a little more complicated. When
a customer requests a metric size (ex: M10 x from. A JIS B1190 M8 x 1.25 Flange Nut will
1.5 x 50 Flange Bolt, Property Class 10.9, Plain) assemble onto an M8 x 1.25 x 10 Flange
we often have to ask, "Is there a dimensional Bolt made to DIN 6921.
standard that you need these to meet?"
The strength levels are the same for all of these
There are five main standards organizations
standards organizations. A property class 10.9
that specify the dimensions for metric sizes
of hex flange screws and flange nuts: flange bolt made to ASME B18.2.3.9M is the
same strength as a 10.9 flange bolt made to
ANSI - American National EN 1641. A property class 10 flange nut made
Standards Institute and/or ASME - to ISO 4162 will be strong enough to properly
American Society of Mechanical Engineers assemble a property class 10.9 flange bolt
ASME B18.2.3.4M Metric Hex Flange Screws
made to DIN 6921.
ASME B18.2.3.9M Metric Heavy Hex Flange Screws
ASME B18.2.4.5M Metric Flange Nuts
The main difference you can run into is that the
DIN - German Industrial Standards width across the flats (the wrench size needed
DIN 6921 Metric Hex Flange Bolts to assemble the nut or screw) can be different
DIN 6923 Metric Hexagon Nuts with Flange between these different dimensional
ISO - International Standards Organization standards.
ISO 4162 Hexagon Flange Bolt - Small Series
ISO 4161 Hexagon Nuts with Flange The tables on the following pages will give you
a quick reference as to the differences and
JIS - Japanese Industrial Standards similarities of flange products that are
JIS B1189 Metric Hex Flange Bolts
made to these standards.
JIS B1190 Metric Flange Nuts

EN - European Norm (EU standards)

EN 1662 Metric Hex Flange Bolts - Small Series
EN 1665 Metric Flange Bolts
EN 1661 Metric Flange Nut

*The dimensional requirements for these five organizations

can vary depending on the diameter you are dealing with.
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 RESOURCE GUIDE

Metric Hex Flange Screws

S K
C

Dc

DIAMETER M5 M6 M8 M10 M12 M14 M16 M20

Width Across Flats - S (Max)

ASME B18.2.3.4M 7 8 10 13 15 18 21 *
ASME B18.2.3.9M 8 10 13 15 18 21 24 30

DIN 6921 8 10 13 15 16 18 21 27

ISO 4162 7 8 10 13 15 18 21 *

JIS B1189-2005 8 10 12 14 17 19 22 *
EN 1662 7 8 10 13 15 18 21 *

EN 1661 8 10 13 16 18 21 24 30

Flange Diameter - Dc (max)

ASME B18.2.3.4M 11.4 13.6 17.0 20.8 24.7 28.6 32.8 *
ASME B18.2.3.9M 11.8 14.2 18.0 22.3 26.6 30.5 35.0 43.0
DIN 6921 11.8 14.2 18.0 22.3 26.6 30.5 35.0 43.0
ISO 4162 11.4 13.6 17.0 20.8 24.7 28.6 32.8 *
JIS B1189-2005 12.0 14.0 17.5 21.0 25.0 29.0 33.0 *
EN 1662 11.4 13.6 17.0 20.8 24.7 28.6 32.8 *
EN 1665 11.8 14.2 18.0 22.3 26.6 30.5 35.0 43.0
Head Height - K (max)
ASME B18.2.3.4M 5.6 6.9 8.5 9.7 12.1 12.9 15.2 *
ASME B18.2.3.9M 5.8 6.6 8.1 10.4 11.8 13.7 15.4 18.9
DIN 6921 5.4 6.6 8.1 9.2 11.5 12.8 14.4 17.1
ISO 4162 5.6 6.8 8.5 9.7 11.9 12.9 15.1 *
JIS B1189-2005 5.0 6.0 8.0 10.0 11.5 13.5 15.0 *
EN 1662 5.6 6.9 8.5 9.7 12.1 12.9 15.2 *
EN 1665 5.8 6.6 8.1 10.4 11.8 13.7 15.4 18.9
Flange Thickness - C (min)
ASME B18.2.3.4M 1.0 1.1 1.2 1.5 1.8 2.1 2.4 *
ASME B18.2.3.9M 1.0 1.1 1.2 1.5 1.8 2.1 2.4 3.0
DIN 6921 1.0 1.1 1.2 1.5 1.8 2.1 2.4 3.0
ISO 4162 1.0 1.1 1.2 1.5 1.8 2.1 2.4 *
JIS B1189-2005 0.7 0.8 1.1 1.2 1.4 1.6 1.8 *
EN 1662 1.0 1.1 1.2 1.5 1.8 2.1 2.4 *
EN 1665 1.0 1.1 1.2 1.5 1.8 2.1 2.4 3.0

*Dimensions for this size are not listed in spec.

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 RESOURCE GUIDE

Metric Hex Flange Nuts

S M
C

Dc

DIAMETER M5 M6 M8 M10 M12 M14 M16 M20

Width Across Flats - S (max)

ASME B18.2.4.4M 8 10 13 15 18 21 24 30
DIN 6923 8 10 13 15 18 21 24 30

ISO 4161 8 10 13 15 18 21 24 30

JIS B1190-1987 8 10 12 14 17 19 22 *

EN 1661 8 10 13 16 18 21 24 30
Flange Diameter - Dc (max)

ASME B18.2.4.4M 11.8 14.2 17.9 21.8 26.0 29.9 34.6 42.8

DIN 6923 11.8 14.2 17.9 21.8 26.0 29.9 34.5 42.8
ISO 4161 11.8 14.2 17.9 21.8 26.0 29.9 34.5 42.8
JIS B1189-1987 12.0 14.0 17.5 21.0 25.0 29.0 33.0 *
EN 1661 11.8 14.2 17.9 21.8 26.0 29.9 34.5 42.8
Nut Height - M (max)
ASME B18.2.4.4M 5.0 6.0 8.0 10.0 12.0 14.0 16.0 20.0
DIN 6923 5.0 6.0 8.0 10.0 12.0 14.0 16.0 20.0
ISO 4161 5.0 6.0 8.0 10.0 12.0 14.0 16.0 20.0
JIS B1190-1987 5.0 6.0 8.0 10.0 11.5 13.5 15.0 *
EN 1661 5.0 6.0 8.0 10.0 12.0 14.0 16.0 20.0
Flange Thickness - C (min)
ASME B18.2.4.4M 1.0 1.1 1.2 1.5 1.8 2.1 2.4 3.0
DIN 6923 1.0 1.1 1.2 1.5 1.8 2.1 2.4 3.0
ISO 4161 1.0 1.1 1.2 1.5 1.8 2.1 2.4 3.0
JIS B1190-1987 0.7 0.8 1.1 1.2 1.4 1.6 1.8 *
EN 1661 1.0 1.1 1.2 1.5 1.8 2.1 2.4 3.0

*Dimensions for this size are not listed in spec.

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