[USMA:24347] Re: iVDR "inch" drives?

Fri, 03 Jan 2003 15:45:17 -0800

2003-01-03
 
This is an update of an article published in the September-
October 1993 issue of this newsletter.
Pipe is one of the most ubiquitous products in construction.
It is made of a wide variety of materials, including galvanized
steel, black steel, copper, cast iron, concrete, and various
plastics such as ABS, PVC, CPVC, polyethylene, and poly-
butylene, among others.
But like wood 2-by-4s, which are not really 2 inches by 4
inches, pipe is identified by "nominal" or "trade" names that
are related only loosely to actual dimensions. For instance,
a 2-inch galvanized steel pipe has an inside diameter of about
2-1/8 inches and an outside diameter of about 2-5/8 inches.
It is called "2-inch pipe" only for the sake of convenience.
Since few, if any, pipe products have actual dimensions that
are in even, round inch-pound numbers, there is no need to
convert them to even, round metric numbers. Instead, only
their
names
change- from inch-pound to metric. Pipe cross
sectional sizes do not change. Fittings, flanges, couplings,
valves, and other piping components are renamed in like
manner, as are pipe threads.
Here are the inch-pound names for pipe products (called NPS
or "nominal pipe size") and their metric equivalents (called
DN or "diameter nominal"). The metric designations conform
to International Standards Organization (ISO) usage and
apply to all plumbing, natural gas, heating oil, and miscel-
laneous piping used in buildings. Reinforced concrete pipe
and corrugated steel pipe used in highways and other civil
works construction also use these designations.
Note that all whole-number inch designations on the follow-
ing chart convert to multiples of 25 mm except for 3-inch
pipe, which ISO designates as 80 mm.
NPS
DN
NPS
DN
1/8"
6 mm
8"
200 mm
3/16"
7 mm
10"
250 mm
1/4"
8 mm
12"
300 mm
3/8"
10 mm
14"
350 mm
1/2"
15 mm
16"
400 mm
5/8"
18 mm
18"
450 mm
3/4"
20 mm
20"
500 mm
1"
25 mm
24"
600 mm
1-1/4"
32 mm
28"
700 mm
1-1/2"
40 mm
30"
750 mm
2"
50 mm
32"
800 mm
2-1/2"
65 mm
36"
900 mm
3"
80 mm
40"
1000 mm
3-1/2"
90 mm
44"
1100 mm
4"
100 mm
48"
1200 mm
4-1/2"
115 mm
52"
1300 mm
5"
125 mm
56"
1400 mm
6"
150 mm
60"
1500 mm
(continued on page 2)
Construction Metrication
is the newsletter of the Construction Metrication Council of the National Institute of
Building Sciences. Reproduction and distribution of its contents is encouraged provided the Council receives attribution.
This and previous newsletters may be viewed on the NIBS Web site at
www.nibs.org
.
2
CONSTRUCTION
METRICATION COUNCIL
National Institute of Building Sciences
1090 Vermont Avenue, N.W., Suite 700
Washington, D.C. 20005-4905
Telephone 202-289-7800; fax 202-289-
1092
E-mail: [EMAIL PROTECTED]
Internet: www.nibs.org
Construction Metrication
is a quarterly newsletter
published by the Construction Metrication Council to
disseminate information about construction metrication
activities. The National Institute of Building Sciences created
the Council in 1992 to provide industry-wide, public and
private sector support for the metrication of federal construc-
tion and to promote the adoption and use of the metric
system of measurement as a means of increasing the interna-
tional competitiveness, productivity, and quality of the U.S.
construction industry.
The National Institute of Building Sciences is a non-
profit, nongovernmental organization authorized by Congress
to serve as an authoritative source on issues of building science
and technology.
The Council is an outgrowth of the Construction
Subcommittee of the Metrication Operating Committee of the
federal Interagency Council on Metric Policy. The Construc-
tion Subcommittee was formed in 1988 to further the objec-
tives of the 1975
Metric Conversion Act
, as amended by the
1988
Omnibus Trade and Competitiveness Act
. To foster
effective private sector participation, the activities of the
Subcommittee were transferred to the Council in April 1992.
Membership in the Council is open to all public and
private organizations and individuals with a substantial interest
in and commitment to the Council's purposes. The Council
publishes the
Metric Guide for Federal Construction
and this
newsletter. It is funded primarily by contributions from
federal agencies but also receives private sector support.
Chairman
:
Thomas R. Rutherford, P.E., Department of De-
fense
Executive Director
:
William A. Brenner, AIA
Board of Direction
:
William Aird, P.E., National Society of
Professional Engineers; Gertraud Breitkopf, R.A., GSA Public
Buildings Service; David Cox, P.E., Federal Highway
Administration; Garner W. Duvall, P.E. , National Capitol
Region, General Services Administration; James Gross, P.E.,
National Institute of Standards and Technology, retired;
Debbie Nauta-Rodriguez, AIA, Smithsonian Institution; Arnold
Prima, FAIA, Washington Building Congress; Mary Fenelon,
Construction Information Group/McGraw-Hill; Gerald Under-
wood, American National Metric Council; Dwain Warne, P.E.,
GSA Public Buildings Service, retired; Lorelle Young, U.S.
Metric Association; Werner Quasebarth, American Institute
of Steel Construction.
The following examples show how inch-pound names for pipe products are
converted to metric designations. By changing their names and referring to the
appropriate specification, existing pipe products and thread sizes can be specified
in metric.
#
In a specification, 1-1/2-inch, 2-inch, 4-inch, and 6-inch pipe are shown as
DN40, DN50, DN100 and DN150 pipe.
Comment: The specification will further elaborate, for
example, that "Pipe sizes DN50 or less are to be black steel
per ASTM A135, Schedule 40, and threaded per ASME
B1.20.1. Pipe sizes greater than DN50 are to be black steel
per ASTM A135, Schedule 10, and roll grooved." By
specifying the appropriate manufacturing standard, the
pipe's actual inside diameter (ID), outside diameter (OD),
and material are assured.
#
An installation standard calling for all pipe threads to be per ASME
B1.20.1 remains unchanged.
Comment: The NPT (National Standard Pipe Taper) pipe
thread form is the same but its name is converted; for
example, 1/2-inch NPT becomes DN15 NPT.
#
An installation standard calling for the use of a minimum 2-inch drain valve
is revised to indicate the use of a minimum DN50 drain valve.
Comment: Since the 2-inch size is actually a nominal pipe
size (NPS), it is converted to a nominal metric size (DN) as
opposed to using the conversion of 1 inch equals 25.4 mm.
#
A 2-inch Class 150 malleable iron 90� elbow per ASME B16.3 is
designated as a DN50 Class 150 malleable iron 90� elbow per ASME B16.3.
Comment: Pipe fittings manufactured to ASME B16.3 are
threaded with ASME B1.20.1 pipe threads. Therefore, a
DN50 90� elbow will have DN50 NPT pipe threads. The
term "Class 150", which refers to a pressure rating, re-
mains unchanged (since the term does not designate an
inch-pound increment from which it was derived, it can be
used with metric nomenclature).
#
A 6-inch � 6-inch � 4-inch, Class 125, Grade A, reducing tee per ASME
B16.1 is designated a DN150 � DN150 � DN100, Class 125, Grade A,
reducing tee per ASME B16.1.
Comment: All product dimensions covered by ASME B16.1
remain unchanged.
#
A 1/2-14 NPT thread per ASME B1.20.1 is designated DN15-14 NPT per
ASME B1.20.1.
Comment: In the above designation, "14" refers to 14
threads per inch. Since the term does not designate an
inch-pound increment from which it was derived, it can be
used with metric nomenclature. It is interesting to note
that IS0 7, which is a recognized international pipe thread
standard, refers to the number of threads per 25.4 mm, or 1
inch.
The material for this article was developed by the Mechanical
Task Group of the Construction Metrication Council, National
Institute of Building Sciences. Examples were provided by Roger
Wilkins of Grinnell Corporation.
3
METRIC FACTS: FORCE
How much force will it take to get up to speed? What force
will be exerted on the foundation? The metric answers to
these questions are expressed in
newtons
(N). The newton
is defined as the force that when applied to a free mass of
1 kilogram (kg) will impart an acceleration of 1 meter per
second per second (kg m/s
2
).
One of the many advantages of metric is that it uses a
different unit for mass (kg) than it uses for force (N), thus
reducing the mass-force-weight confusion.
The inch-pound unit for force is the poundal and the
conversion is 7.233 poundals per newton. On the earth at
sea level, a mass of one kilogram will produce a force on its
support of 9.806 newtons.
Problem:
A crane on the earth at sea level lifts a mass of 500
kilograms. What force in newtons is imposed on the crane?
Solution:
500 kg � (9.806 N/kg) = 4903 N
By Oscar Fisher; used with the permission of the American Society of Mechanical Engineers.
SMART METRICATION TIPS:
P
Obtain a metric tape measure right away. So equipped,
you readily can adapt to metric usage. Unequipped, you
can't do your job. Some advocate dual unit tapes, others
metric-only tapes. Take your pick.
P
You won't need many other metric tools. There is no
such thing as a metric hammer, saw, screwdriver, chisel,
pliers, power drill, level, or trowel. You probably already have
a set of metric wrenches.
P
If you scale dimensions off drawings, use a metric scale.
One 3-sided metric scale can be used for both architectural
and engineering drawings. Don't use an inch scale ­ you'll
make mistakes.
P
Try to use only metric measures right from the start. It
will be hard at first but you'll soon get the hang of it. Talk
"metric-only" on the work site and adopt a pro-metric tone.
Experience has shown that a positive, professional attitude
about metrication minimizes problems.
P
Do not convert metric drawings and specs back to
conventional units. This "shortcut" invariably leads to
mistakes, so
resist the temptation
. Execute all work in metric
units with metric tape measures and you'll learn faster, too.
P
Conversions are unnecessary except, perhaps, when
dealing with some suppliers or comparing costs. Double
check any conversions you do make.
P
Be prepared to submit shop drawings and product
information in metric units.
METRIC RULES-OF-THUMB
#
1 mm = about 1/25 inch = thickness of a dime
#
25 mm = about 1 inch (1" = 25.4 mm)
#
300 mm = about 1 foot (12" = 304.8 mm)
#
1000 mm = 1 m = about 3 feet + 10% more
#
1 m� = roughly 10 square feet (1m� = 10.76 ft�)
#
1 L = about 1 quart (1L = 1.06 qt)
#
1 m� = about 35 cubic feet (about 30% more than a yd�)
#
1 kg = about 2.2 pounds
#
1000 kg = 1Mg = 1 metric ton = about 2200 pounds
#
100 kPa = about 15 psi; 1 MPa = about 150 psi
Address Service Requested
The Construction Metrication Newsletter
FHWA STAYS THE COURSE
On June 17, 1999, the Federal Highway Administration
issued a final rule adopting the
Guide to Metric Con-
version
, AASHTO, 1993, and
Traffic Engineering
Metric Conversion Factors, 1993-Addendum to the
Guide to Metric Conversion
, AASHTO, October 1993,
as the national standards for traffic control devices (23
CFR Part 655, Subpart F). This formalized FHWA's
interim rule on metric conversion published on June 11,
1996. As background to its rulemaking, FHWA stated
in part (with emphasis added):
"Section 1211(d) of the Transportation Equity Act for
the 21st Century (TEA-21) (Pub. L. 105-178, 112 Stat.
107) removed the target date for metric conversion,
thereby allowing the State departments of transporta-
tion (DOTs) the option of converting to the Interna-
tional System of Measurements (SI). Section 205(c)(2)
of the National Highway System Designation Act of
1995 (Pub. L. 104-59, 109 Stat. 568) was amended by
Shouldn't a 1/2" be called "a 15" and a 3/4" be called "a 20"?  This is from the chart below.
 
 
John
 
----- Original Message -----
From: "Joseph B. Reid" <[EMAIL PROTECTED]>
To: "U.S. Metric Association" <[EMAIL PROTECTED]>
Sent: Friday, 2003-01-03 10:15
Subject: [USMA:24337] Re: iVDR "inch" drives?

> Further to USMA 24335 in which Carleton  MacDonald gave examples of
> approximate translation of sizes between inches and millimetres,
> French plumbing uses British plumbing standards (possibly the French
> got the bathing habit from the British who learned it from India).
> In France a 1/2" pipe is "un treize" (a thirteen) and a 3/4" pipe is
> "un dix-neuf" (a nineteen).
>
> --
> Joseph B. Reid
> 17 Glebe Road West
> Toronto  M5P 1C8 Telephone 416-486-6071
>
 
 
 

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