## Overview

The International System of Units (SI) is a modernized version of the metric system established by international agreement. The metric system of measurement was developed during the French Revolution and was first promoted in the U.S. by Thomas Jefferson. Its use was legalized in the U.S. in 1866. In 1902, proposed congressional legislation requiring the U.S. Government to use the metric system exclusively was defeated by a single vote.

SI provides a logical and interconnected framework for all measurements in science, industry, and commerce. The metric system is much simpler to use than the existing English system since all its units of measurement are divisible by 10.

## Conversion Factors

The following list provides the conversion relationship between U.S. customary units and SI (International System ) units. The proper conversion procedure is to multiply the specified value on the left (primarily U.S. customary values) by the conversion factor exactly as given below and then round to the appropriate number of significant digits desired. For example, to convert 11.4 ft to meters: 11.4 X 0.3048 = 3.47472, which rounds to 3.47 meters. Do not round either value before performing the multiplication, as accuracy would be reduced. A complete guide to the SI system and its use can be found in ASTM E 380, Metric Practice.

Select this link for an explanation of WSDOT's foot to meter conversion method.

For a useful conversion tool, download Convert.exe, a freeware program written by Joshua F. Madison. This has been checked and found to be virus free.

Note that Convert.exe uses the 1959 conversion factors for distance i.e. the 1959 definitions of inch and foot and their derived measurements, the ton to kilogram conversion factor differs from the conversion factor published on this page by 1 in the 7th digit, the Fahrenheit to Kelvin conversion factor differs by 0.017 degree Kelvin, the BTU/hour to watt conversion differs by 3 in the 4th digit, and the ft/sec2 to m/sec2 conversion differs by 1 in the 6th digit.

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## Conversion Symbols

The prefixes and symbols listed below are commonly used to form names and symbols of the decimal multiples and sub multiples of the SI units.

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 INTERIM UNITS OF MEASUREAs suggested by Federal Standard 376BJanuary 27, 1993 AS USED IN THESTANDARD ITEM TABLE METRIC EQUIVALENT ACRE hectare (ha) CUBIC FOOT cubic meter (m3) CUBIC YARD cubic meter (m3) GALLON/MGALLON liter (L), cubic meter (m3) HUNDRED Hundred for traffic buttons HUNDRED WEIGHT kilogram (kg) LINEAR FOOT meter (m) MBOARD FEET cubic meter (m3) MILE kilometer (km) NAUTICAL MILE Nautical Mile POUND kilogram (kg) for massnewton (N) for force SQUARE FOOT square meter (m2) SQUARE YARD square meter (m2) TON tonne (t)

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 UNITS OF MEASUREMENTUSED IN SPECIAL PROVISIONSAND GENERAL SPECIAL PROVISIONS METRIC EQUIVALENT GAGE; GAUGE METAL THICKNESS gage (mm) FAHRENHEIT TEMPERATURE kelvin (K) or degree Celsius (C) FATHOM WATER DEPTH meter (m) FOOT/LBS TORQUE newton-meter (N-m) LBS/SQ. IN PRESSURES kilopascal (kPa)megapascal (MPa)(if very large number) LBS/SQ. FT kilopascal (kPa) LBS/SQ YD kilopascal (kPa) INCH LINEAR millimeter (mm) KIPS; KSI TENSION kilopascal (kPa) ormegapascal (MPa) LBS/ACRE EROSION CONTROL kilograms/hectare LBS/CU. FT. DENSITY kilogram per cubic meter (kg/m3) MIL THICKNESS micrometer (um) FT. LBS./SEC. HORSE POWER watt (W)

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 UNITS OF MEASUREMENTS USEDON CONTRACT PLANS METRIC EQUIVALENT DEGREES/BEARINGS No change for surveying. STATIONING 1,000 meters = 1 station MILEPOSTS This one is still under review as mileposts are part of the signing issue. Use mileposts for now, but also state kilometerposts. ELEVATIONS meter (m)

 UNITS OF MEASUREMENTS USED IN COMMERCIAL STANDARDS METRIC EQUIVALENT GALS/HR or MIN (PUMPS) liters per second (L/s) 500 GALLON TANKS cubic meter (m3) but it could also possibly be in liter (L) 55 GALLON DRUMS cubic meter (m3) or liter (L) for liquid 94 LBS/SACK (CEMENT) kilogram (kg) DIAMETER OF REINFORCING STEEL millimeter (mm) LBS/FT OF REINFORCING STEEL kilogram per meter (kg/m) BUSHEL cubic meter (m3)

## Length Conversion Factors

 Length To convert from to multiply by mile (US Statute) kilometer (km) 1.609347 inch (in) millimeter (mm) 25.4 * inch (in) centimeter (cm) 2.54 * inch (in) meter (m) 0.0254 * foot (ft) meter (m) 0.3048 * yard (yd) meter (m) 0.9144 *

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## Area Conversion Factors

 Area To convert from to multiply by square foot (sq ft) square meter (sq m) 0.09290304 E square inch (sq in) square meter (sq m) 0.00064516 E square yard (sq yd) square meter (sq m) 0.83612736 E acre (ac) hectare (ha) 0.4047

## Volume Conversion Factors

 Volume To convert from to multiply by cubic inch (cu in) cubic meter (cu m) 0.00001639 cubic foot (cu ft) cubic meter (cu m) 0.02831685 cubic yard (cu yd) cubic meter (cu m) 0.7645549 U.S. liquid** gallon (gal) cubic meter (cu m) 0.00378541 gallon (gal) liter 3.785 fluid ounce (fl oz) milliliters (ml) 29.57353 fluid ounce (fl oz) cubic meter (cu m) 0.00002957

## Force Conversion Factors

 Force To convert from to multiply by kip (1000 lb) kilogram (kg) 453.6 kip (1000 lb) newton (N) 4,448.222 pound (lb) avoirdupois kilogram (kg) 0.4535924 pound (lb) newton (N) 4.448222

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## Pressure or Stress Conversion Factors

 Pressure or stress kip per square inch (ksi) megapascal (MPa) 6.894757 pound per square foot (psf) kilogram per square meter (kg/sq m) 4.8824 pound per square foot (psf) pascal (Pa) 47.88 pound per square inch (psi) pascal (Pa) 6,894.757 pound per square inch (psi) megapascal (MPa) 0.00689476

## Mass Conversion Factors

 Mass (weight) pound (lb) avoirdupois kilogram (kg) 0.4535924 ton, 2000 lb kilogram (kg) 907.1848 grain kilogram (kg) 0.0000648 Mass (weight) per length kip per linear foot (klf) kilogram per meter (kg/m) 0.001488 pound per linear foot (plf) kilogram per meter (kg/m) 1.488 Mass per volume (density) pound per cubic foot (pcf) kilogram per cubic meter (kg/cu m) 16.01846 pound per cubic yard (lb/cu yd) kilogram per cubic meter (kg/cu m) 0.5933

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## Temperature Conversion Factors

 Temperature degree Fahrenheit (F) degree Celsius (C) tc=(tF-32)/1.8 degree Fahrenheit (F) kelvin (K) tk = (tF+459.7)/1.8 kelvin (K) degree Celsius (C) tc=tk-273.15 Energy and heat British thermal unit(Btu) joule (J) 1055.056 calorie (cal) joule (J) 4.1868E Btu/degree F x hr x ft2 W/m2 - degree K 5.678263 kilowatt-hour (kwh) joule (J) 3,600,000E British thermal unit per pound (Btu/lb) calories per gram (cal/g) 0.55556 British thermal unit per hour (Btu/hr) watt (W) 0.2930711

## Power Conversion Factors

 Power horsepower (hp) (550 ft-lb/sec) watt (W) 745.6999 E Velocity mile per hour (mph) kilometer per hour(km/hr) 1.60934 mile per hour (mph) meter per second (m/s) 0.44704 Permeability darcy centimeter per second (cm/sec) 0.000968 feet per day (ft/day) centimeter per second (cm/sec) 0.000352 *indicates that the factor given is exact.**One U.S. gallon equals 0.8327 Canadian gallon.t--A pascal equals 1.000 newton per square meter. Note:One U.S. gallon of water weighs 8.34 pounds (U.S.) at 60 degrees F.One cubic foot of water weighs 62.4 pounds (U.S.).One milliliter of water has a mass of 1 gram and has a volume of one cubic centimeter.One U.S. bag of cement weighs 94 lbs.

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## More Useful Conversion Factors

 Quantity From English Units To Metric Units Multiply by* Length mile km 1.609347 yard m 0.9144** foot m 0.3048** inch mm 25.40** Area square mile km 2 2.590 acre m 2 4047 acre hectare 0.4047 square yard m 2 0.8361 square foot m 2 0.092 90 square inch mm 2 645.2 Volume acre foot m 3 1 233 cubic yard m 3 0.7646 cubic foot m 3 0.028 32 cubic foot L (1000 cm 3) 28.32 100 board feet m 3 0.2360 gallon L (1000 cm 3) 3.785 Mass lb kg 0.4536 kip (1000 lb) metric ton (1000kg) 0.4536 Mass/unit length plf kg/m 1.488 Mass/unit area psf kg/m 2 4.882 Mass density pcf kg/m 3 16.02 Force lb N 4.448 kip kN 4.448 Force/unit length plf N/m 14.59 klf kN/m 14.59 Pressure, stress, modules of elasticity psf Pa 47.88 ksf kPa 47.88 psi kPa 6.895 ksi MPa 6.895 Bending moment, torque, moment of force ft-lb N . m 1.356 ft-kip kN . m 1.356 * 4 significant digits**denotes exact conversion

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 Quantity From English Units To Metric Units Multiply by* Moment of mass lb . ft kg . m 0.1383 Moment of inertia lb . ft2 kg . m 2 0.042 14 Second moment of area in4 mm4 416 200 Section modulus in3 mm3 16 390 Power ton (refrig) kW 3.517 Btu/s kW 1.054 hp (electric) W 745.7 Btu/h W 0.2931 Volume rate of flow ft 3/s m 3/s 0.028 32 cfm m 3/s 0.000 471 9 cfm L/s 0.4719 mgd m 3/s 0.0438 Velocity, speed ft/s m/s **0.3048 Acceleration f/s 2 m/s 2 0.3048 Momentum lb . ft/sec kg . m/s 0.1383 Angular momentum lb . ft 2/s kg . m 2/s 0.042 14 Plane Angle degree rad 0.017 45 mrad 17.45 * 4 significant digits**denotes exact conversion

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## Pavement Conversion Factors

 METRIC CONVERSION – PAVEMENTS Roadway Dimensions Bridge Ht. PCCP Thickness' Resilient Modulus ft m ft m (inches) (mm) psi MPa Lane 12 3.6 14.5 4.4 9 225 3,000 21 Shoulder 4 1.2 16.0 4.9 10 250 4,000 28 10 3.0 11 275 5,000 34 12 300 10,000 69 12,000 83 15,000 103 20,000 138

 Typical Density Values Axle Loads Tire Loads (per tire width) pcf kg/m 2 lbs kN lbs/inch kg/mm PCCP 150 2403 18,000 80 500 9 ACP 137/0.10' depth 2439

 TYPICAL QUANTITIES Asphalt Concrete Paving Quantities (metric tons/kilometer) Depth of Pavement (ft) 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50 0.55 0.60 0.65 0.70 0.75 (mm) 30 45 60 75 90 105 120 135 150 165 180 195 210 225

 Width of Pavement (ft) (M) | Metric tons per kilometer 4 1.2 | 88 132 176 219 263 307 351 395 439 483 527 571 614 658 6 1.8 | 132 198 263 329 395 461 527 593 658 724 790 856 922 988 8 2.4 | 176 263 351 439 527 614 702 790 878 966 1,053 1,141 1,229 1,317 10 3.0 | 219 329 439 549 658 768 878 988 1,097 1,207 1,317 1,427 1,536 1,646 11 3.3 | 241 362 483 604 724 845 966 1,086 1,207 1,328 1,448 1,569 1,690 1,811 12 3.6 | 263 395 527 658 790 922 1,053 1,185 1,317 1,448 1,580 1,712 1,843 1,975 22 6.6 | 483 724 966 1,207 1,448 1,690 1,931 2,173 2,414 2,655 2,897 3,138 3,380 3,621 24 7.2 | 527 790 1,053 1,317 1,580 1,843 2,107 2,370 2,634 2,897 3,160 3,424 3,687 3,950 Based on 2439 kg/m 3 ; 30 mm compacted depth = 73.17 kg/m 2

## Pavement Marking Conversion Chart

 Wet Material Thickness Edge Line Coverage Area Coverage English mils (0.001") Metric mm (0.001M) English Ft/gal Met./Eng. M/gal Metric M/Liter English SF/gal Met./Eng. SM/gal Metric SM/Liter 1.0 0.025 4832 1473 393.7 1611 150 39.37 10.0 0.254 483 147 39.4 161 15 3.94 15.0 0.381 322 98.2 26.2 107 10 2.62 19.7 0.500 245 74.8 20.0 82 7.6 2.00 20.0 0.508 242 73.6 19.7 81 7.5 1.97 25.0 0.635 193 58.9 15.7 64 6.0 1.57 30.0 0.762 161 49.1 13.1 54 5.0 1.31 35.0 0.889 138 42.1 11.2 46 4.3 1.12 39.4 1.000 123 37.4 10.0 41 3.8 1.00 40.0 1.016 121 36.8 9.8 40 3.7 0.98 45.0 1.143 107 32.7 8.7 36 3.3 0.87 49.2 1.250 98 29.9 8.0 33 3.0 0.80 50.0 1.270 97 29.5 7.9 32 3.0 0.79 59.1 1.500 82 24.9 6.7 27 2.5 0.67 60.0 1.524 81 24.5 6.6 27 2.5 0.66 78.7 2.000 61 18.7 5.0 20 1.9 0.50 88.6 2.250 55 16.6 4.4 18 1.7 0.44 90.0 2.286 54 16.4 4.4 18 1.7 0.44 98.4 2.500 49 15.0 4.0 16 1.5 0.40 100.0 2.540 48 14.7 3.9 16 1.5 0.39 118.1 3.000 41 12.5 3.3 14 1.3 0.33 120.0 3.048 40 12.3 3.3 13 1.2 0.33 236.2 6.000 20 6.2 1.7 7 0.6 0.17 250.0 6.350 19 5.9 1.6 6 0.6 0.16 255.9 6.500 19 5.8 1.5 6 0.6 0.15 260.0 6.604 19 5.7 1.5 6 0.6 0.15 WDB 4.22.97

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## Sheet Metal Conversion Factors

SHEET METAL Most specification references use gage number followed by the decimal inch thickness. Example: 22 gage (0.034 inch) Metric specifications use the absolute mm thickness. It is not the intent of this guidance to change the thickness of currently used sheeting. The following chart may be used to specify sheet metal. The thickness under "Specify" is thinner than the actual gage thickness, since specifications give minimum thickness.

 Gage Inch Exact (mm) Specify (mm) Percent ThinnerThan "Exact" Value 32 0.0134 0.3404 0.34 0.1 30 0.0157 0.3988 0.39 2.2 28 0.0187 0.4750 0.47 1.1 26 0.0217 0.5512 0.55 0.2 24 0.0276 0.7010 0.70 0.1 22 0.0336 0.8534 0.85 0.4 20 0.0396 1.0058 1.0 0.6 18 0.0516 1.3106 1.3 0.8 16 0.0635 1.6129 1.6 0.8 14 0.0785 1.9939 1.9 4.7 12 0.1084 2.7534 2.7 1.9 10 0.1382 3.5103 3.5 0.3 8 0.1681 4.2697 4.2 1.6

This schedule was developed since no existing material was found to clearly identify existing sheeting in metric units. Until a more efficient method is developed to address this issue, specifiers may wish to retain the gage number in specifications, and couple this with a rounded mm size in parenthesis.

## Reinforcing Steel Conversion Factors

REINFORCING STEEL

WSDOT Metric projects will continue to use U.S. Customary units on PS&E's.

The following table shows the current U.S. customary rebar sizes in relationship to the respective diameters and cross-sectional areas.

 Customary English System Metric Equivalent U. S. Customary Designation Diameter (in.) Area (in 2) Diameter (mm) Area (mm 2) #3 0.375 0.11 9.5 71 #4 0.500 0.20 12.7 127 #5 0.625 0.31 15.9 198 #6 0.750 0.44 19.1 285 #7 0.875 0.60 22.2 388 #8 1.000 0.79 25.4 507 #9 1.125 1.00 28.6 641 #10 1.270 1.27 32.3 817 #11 1.410 1.56 35.8 1007 #14 1.693 2.25 43.0 1452 #18 2.257 4.00 57.3 2581

## Wire Conversion Factors

SEVEN-WIRE, UNCOATED STRAND FOR PRESTRESSED CONCRETE STRUCTURES The prestressing industry again uses the soft conversion for all dimensional units of prestressing wire. This soft conversion is utilized worldwide and a copy of the equivalent physical properties for Grade 270 low-relaxation strand, as provided by Florida Wire and Cable Company, is provided below:

 270 GRADE LOW-RELAXATION ASTM A-416 Nominal Strand Diameter Minimum Strength Area (mm) (in.) (kN) (lb.) (mm 2) (in 2) 10 (3/8) 102.3 (23,000) 54.8 (0.085) 11 (7/16) 137.9 (31,000) 74.2 (0.115) 12 (15/32) 160.1 (36,000) 85.8 (0.133) 13 (1/2) 183.7 (41,300) 98.7 (0.153) 14 (9/16) 230.0 (51,700) 123.9 (0.192) 15 (0.600) 260.6 (58,600) 140.0 (0.217)

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## Sieve Conversion Factors

SIEVES

 Sieve Designation (W) Standard Alternative Nominal Sieve Opening Permissible Variation of Average Opening from the Standard Sieve Designation Intermediate Tollerance Maximum Individual Opening Nominal Wire Diameter (in.) (y) + or (x) (x) (mm) 125 mm 5 in. 5 3.70 mm 130.0 mm 130.9 mm 8.00 106 mm 4.24 in. 4.24 3.20 mm 110.2 mm 111.1 mm 6.40 100 mm 4 in. 4 3.00 mm 104.0 mm 104.8 mm 6.30 90 mm 3 1/2 in. 3.5 2.70 mm 93.6 mm 94.4 mm 6.08 75 mm 3 in. 3 2.20 mm 78.1 mm 78.7 mm 5.80 63 mm 2 1/2 in. 2.5 1.90 mm 65.6 mm 66.2 mm 5.50 53 mm 2.12 in. 2.12 1.60 mm 55.2 mm 55.7 mm 5.15 50 mm 2 in. 2 1.50 mm 52.1 mm 52.6 mm 5.05 45 mm 1 3/4 in. 1.75 1.40 mm 46.9 mm 47.4 mm 4.85 37.5 mm 1 1/2 in. 1.5 1.10 mm 39.1 mm 39.5 mm 4.59 31.5 mm 1 1/4 in. 1.25 1.00 mm 32.9 mm 33.2 mm 4.23 26.5 mm 1.06 in. 1.06 0.80 mm 27.7 mm 28.0 mm 3.90 25.0 mm 1 in. 1 0.80 mm 26.1 mm 26.4 mm 3.80 22.4 mm 0.875 0.70 mm 23.4 mm 23.7 mm 3.50 19.0 mm 3/4 in. 0.750 0.60 mm 19.9 mm 20.1 mm 3.30 16.0 mm 0.625 0.50 mm 16.7 mm 17.0 mm 3.00 13.2 mm 0.530 in. 0.530 0.41 mm 13.83 mm 14.05 mm 2.75 12.5 mm 1/2 in. 0.500 0.39 mm 13.10 mm 13.31 mm 2.67 11.2 mm 7/16 in. 0.438 0.35 mm 11.75 mm 11.94 mm 2.45 9.50 mm 0.375 0.30 mm 9.97 mm 10.16 mm 2.27 8.00 mm 5/16 in. 0.312 0.25 mm 8.41 mm 8.58 mm 2.07 6.70 mm 0.265 in. 0.265 0.21 mm 7.05 mm 7.20 mm 1.87 6.30 mm 1/4 in. 0.250 0.20 mm 6.64 mm 6.78 mm 1.82 5.60 mm No. 3 1/2 0.223 0.18 mm 5.90 mm 6.04 mm 1.68 4.75 mm No. 4 0.187 0.15 mm 5.02 mm 5.14 mm 1.54 4.00 mm No. 5 0.157 0.13 mm 4.23 mm 4 35 mm 1.37 3.35 mm No. 6 0.132 0.11 mm 3.55 mm 3.66 mm 1.23 2.80 mm No. 7 0.11 0.095 mm 2.975 mm 3.070 mm 1.10 2.36 mm No. 8 0.0937 0.080 mm 2.515 mm 2.600 mm 1.00 2.00 mm No. 10 0.0787 0.070 mm 2.135 mm 2.215 mm 0.900 1.70 mm No. 12 0.0661 0.060 mm 1.820 mm 1.890 mm 0.810 1.40 mm No. 14 0.0555 0.050 mm 1.505 mm 1.565 mm 0.725 1.18 mm No. 16 0.0469 0.045 mm 1.270 mm 1.330 mm 0.650 1.00 mm No. 18 0.0394 0.040 mm 1.080 mm 1.135 mm 0.580 0.850 mm No. 20 0.0331 0.035 mm 0.925 mm 0.970 mm 0.510 0.710 mm No. 25 0.0278 0.030 mm 0.775 mm 0.815 mm 0.450 0.600 mm No. 30 0.0234 0.025 mm 0.660 mm 0.695 mm 0.390 0.500 mm No. 35 0.0197 0.020 mm 0.550 mm 0.585 mm 0.340 0.425 mm No. 40 0.0165 0.019 mm 0.471 mm 0.502 mm 0.290 0.355 mm No. 45 0.0139 0.016 mm 0.396 mm 0.425 mm 0.247 0.300 mm No. 50 0.0117 0.014 mm 0.337 mm 0.363 mm 0.215 0.250 mm No. 60 0.0098 0.012 mm 0.283 mm 0.306 mm 0.180 0.212 mm No. 70 0.0083 0.010 mm 0.242 mm 0.263 mm 0.152 0.180 mm No. 80 0.0070 0.009 mm 0.207 mm 0.227 mm 0.131 0.150 mm No. 100 0.0059 0.008 mm 0.174 mm 0.192 mm 0.110 0.125 mm No. 120 0.0049 0.007 mm 0.147 mm 0.163 mm 0.091 0.106 mm No. 140 0.0041 0.006 mm 0.126 mm 0.141 mm 0.076 0.090 mm No. 170 0.0035 0.005 mm 0.108 mm 0.122 mm 0.064 0.075 mm No. 200 0.0029 0.005 mm 0.091 mm 0.103 mm 0.053 0.063 mm No. 230 0.0025 0.004 mm 0.077 mm 0.089 mm 0.044 0.053 mm No. 270 0.0021 0.004 mm 0.066 mm 0.076 mm 0.037 0.045 mm No. 325 0.0017 0.003 mm 0.057 mm 0.066 mm 0.030 0.038 mm No. 400 0.0015 0.003 mm 0.048 mm 0.057 mm 0.025 0.032 mm No. 450 0.0012 0.003 mm 0.042 mm 0.050 mm 0.028 0.025 mm No. 500 0.0010 0.003 mm 0.034 mm 0.041 mm 0.025 0.020 mm No. 635 0.0008 0.003 mm 0.029 mm 0.035 mm 0.020

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## Hard Conversions for Construction Materials

 HARD CONVERSION FOR CONSTRUCTION MATERIALS Structural Steel, M270 Min. Tensile Strength Min. Yield Strength Min. Yield Strength Grade (MPa) (MPa) (ksi) 36 400 250 36 50 450 345 50 50W 485 345 50 70W 620 480 70

 Reinforcing Bars, M31M Grade Tensile and Yield Strengths Metric English Tensile Strength Min. Yield Strength Min. Yield Strength Value Value (MPa) (MPa) (ksi) 300 40 500 300 40 400 60 600 400 60

 Common Concrete Strengths (f'c) Metric (MPa) 20 28 35 43 48 55 English (psi) 3000 4000 5000 6000 7000 8000

 Coefficient of Thermal Expansion Metric Value English Value Steel 0.0000117/oC 0.0000065/oF Concrete 0.0000108/oC 0.000006/oF

 Unit Weights Metric Value English Value Steel 7848.3 kg/m3 490 pcf Concrete 2402.5 kg/m3 150 pcf

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Here are the metric units that will be used by the construction trades. The term "length" includes all linear measurements--length, width, height, thickness, diameter, and circumference.

 Quantity Unit Symbol Surveying length kilometer, meter km, m area square kilometer km2 hectare (10,000 m2) ha square meter m2 plane angle degree (non metric) o minute (non metric) ' second (non metric) " Excavating length meter, millimeter m, mm volume cubic meter m3 Trucking distance kilometer km volume cubic meter m3 mass metric ton (1000 kg) t Paving length meter, millimeter m, mm area square meter m2 Concrete length meter, millimeter m, mm area square meter m2 volume cubic meter m3 temperature degree Celsius oC water capacity liter (1000cm) L mass (weight) kilogram, gram kg, g cross-sectional area square millimeter mm2

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## Pipe Conversion Factors

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 polybutylene, among others.

But like wood 2-by-4's 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 n 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 will change--from inch-pound to metric. Pipe cross sections will not change. Fittings, flanges, couplings, valves, and other piping components will be renamed in like manner as will 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 names conform to International Standards Organization (ISO) usage and apply to all plumbing, natural gas, heating oil, drainage, and miscellaneous piping used in buildings and civil works projects.

 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

**(For pipe over 60 inches, use 1 inch equals 25 mm)

 TABLE 1 PROPOSED METRIC CSP DIAMETER SIZES Proposed Metric (mm) Current Standard (inches) 150 6 200 8 250 10 300 12 375 15 450 18 525 21 600 24 675 27 750 30 825 33 900 36 1050 42 1200 48 1350 54 1500 60 1650 66 1800 72 1950 78 2100 84 2250 90 2400 96 2550 102 2700 108 2850 114 3000 120 3150 126 3300 132 3450 138 3600 144

 TABLE 2 Current (inches) Corrugation Sizes Proposed (millimeters) 2 2/3 x 1/2 68 x 13 3 x 1 76 x 25 5 x 1 125 x 25 3/4 x 3/4 x 7 1/2 19 x 19 x 191 3/4 x 1 x 11 1/2 19 x 25 x 292

 TABLE 3 PIPE WALL THICKNESS CurrentGage Nominal Thickness(inches) Proposed Nominal Thickness(millimeters) 16 0.064 1.6 14 0.079 2.0 12 0.109 2.8 10 0.138 3.5 8 0.168 4.3

 TABLE 4 PIPE ARCH SIZES Corrugations Corrugations Inches Millimeters Inches Millimeters 2 2/3 x 1/2 68 x 13 3 x 1 & 5 x 1 76 x 25 & 125 x 25 Span x Rise Span x Rise Span x Rise Span x Rise 17 x 13 425 x 325 53 x 41 1325 x 1025 21 x 15 525 x 375 60 x 46 1500 x 1150 24 x 18 600 x 450 66 x 51 1650 x 1275 28 x 20 700 x 500 73 x 55 1825 x 1375 35 x 24 875 x 600 81 x 59 2025 x 1475 42 x 29 1050 x 725 87 x 63 2175 x 1575 49 x 33 1225 x 825 95 x 67 2375 x 1675 57 x 38 1425 x 950 103 x 71 2575 x 1775 64 x 43 1600 x 1075 112 x 75 2800 x 1875 71 x 47 1775 x 1175 117 x 79 2925 x 1975 77 x 52 1925 x 1300 128 x 83 3200 x 2075 83 x 57 2075 x 1425 137 x 87 3425 x 2175 142 x 91 3550 x 2275 Note: millimeters equal to inches x 25. Assumed pipe diameters will be x 25.

 TABLE 4A PIPE ARCH SIZES Corrugations Corrugations (inches) (millimeters) 3/4 x 3/4 x 7 1/2 19 x 19 x 191 Span x Rise Span x Rise 20 x 16 500 x 400 23 x 19 575 x 475 27 x 21 675 x 525 33 x 26 825 x 650 40 x 31 1000 x 775 46 x 36 1150 x 900 53 x 41 1325 x 1025 60 x 46 1500 x 1150 66 x 51 1650 x 1275 73 x 55 1825 x 1375 81 x 59 2025 x 1475 87 x 63 2175 x 1575 95 x 67 2375 x 1675 Note: millimeters equal to inches x 25. Assumed pipe diameters will be x 25.

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## Structural Plate Conversion Factors

 STRUCTURAL PLATE DIMENSIONS 6 X 2 Corrugation 31 Inch Corner Radius Span Rise R R ft-in ft-in ft. ft. 13-3 9-4 6.68 16.05 14-11 10-2 7.48 18.98 16-6 11-0 8.29 21.93 18-1 11-10 9.09 24.98 19-8 12-8 9.90 28.04

 TABLE 5M STRUCTURAL PLATE DIMENSIONS 152 x 51 Corrugation 787 mm Corner Radius (millimeters) Span Rise R R 4039 2845 2036 4892 4547 3099 2280 5785 5029 3353 2527 6684 5512 3607 2771 7614 5994 3861 3018 8547

 TABLE 6 STRUCTURAL PLATE THICKNESS Current Specification Proposed Gage Inches Millimeters 12 .111 2.5 10 .140 3.5 8 .170 4.5 7 .188 - 5 .218 5.5 3 .249 6.5 1 .280 7.0 5/16 .318 8.0 3/8 .377 9.5