ASTM C680-89(2002)
(Practice)Standard Practice for Determination of Heat Gain or Loss and the Surface Temperatures of Insulated Pipe and Equipment Systems by the Use of a Computer Program
Standard Practice for Determination of Heat Gain or Loss and the Surface Temperatures of Insulated Pipe and Equipment Systems by the Use of a Computer Program
SCOPE
1.1 The computer programs included in this practice provide a calculational procedure for predicting the heat loss or gain and surface temperatures of insulated pipe or equipment systems. This procedure is based upon an assumption of a uniform insulation system structure, that is, a straight run of pipe or flat wall section insulated with a uniform density insulation. Questions of applicability to real systems should be resolved by qualified personnel familiar with insulation systems design and analysis. In addition to applicability, calculational accuracy is also limited by the range and quality of the physical property data for the insulation materials and systems.
1.2 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 and health practices and determine the applicability of regulatory limitations prior to use.
General Information
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Standards Content (Sample)
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Designation: C 680 – 89 (Reapproved 2002)
Standard Practice for
Determination of Heat Gain or Loss and the Surface
Temperatures of Insulated Pipe and Equipment Systems by
the Use of a Computer Program
This standard is issued under the fixed designation C 680; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope X3.5 Flow Chart Symbols and Their Usage in Information
Processing
1.1 The computer programs included in this practice pro-
X3.9 Standard for Fortran Programming Language
vide a calculational procedure for predicting the heat loss or
gain and surface temperatures of insulated pipe or equipment
3. Terminology
systems. This procedure is based upon an assumption of a
3.1 Definitions—For definitions of terms used in this prac-
uniform insulation system structure, that is, a straight run of
tice, refer to Terminology C 168.
pipe or flat wall section insulated with a uniform density
3.2 Symbols:Symbols—The following symbols are used in
insulation. Questions of applicability to real systems should be
the development of the equations for this practice. Other
resolved by qualified personnel familiar with insulation sys-
symbols will be introduced and defined in the detailed descrip-
tems design and analysis. In addition to applicability, calcula-
tion of the development.
tional accuracy is also limited by the range and quality of the
physical property data for the insulation materials and systems.
where:
1.2 This standard does not purport to address all of the 2 2
h = surface coefficient, Btu/(h·ft ·°F) (W/(m ·K))
safety concerns, if any, associated with its use. It is the
k = thermal conductivity, Btu·in./(h·ft ·°F)(W/(m·K))
responsibility of the user of this standard to establish appro-
k = constant equivalent thermal conductivity introduced
a
priate safety and health practices and determine the applica-
by the Kirchhoff transformation, Btu·in./(h·ft ·F)
bility of regulatory limitations prior to use.
(W/(m·K))
Q = total time rate of heat flow, Btu/h (W)
t
2. Referenced Documents
Q = time rate of heat flow per unit length, Btu/h·ft (W/m)
l
2.1 ASTM Standards:
q = time rate of heat flow per unit area, Btu/(h·ft )
2 2
C 168 Terminology Relating to Thermal Insulation (W/m )
2 2
C 177 Test Method for Steady-State Heat Flux Measure- R = thermal resistance, (°F·h·ft )/Btu (K·m /W)
r = radius, in. (m)
ments and Thermal Transmission Properties by Means of
t = local temperature, °F (K)
the Guarded Hot Plate Apparatus
t = temperature of inner surface of the insulation, °F (K)
i
C 335 Test Method for Steady-State Heat Transfer Proper-
t = temperature of ambient fluid and surroundings, °F
a
ties of Horizontal Pipe Insulation
(K)
C 518 Test Method for Steady-State Heat Flux Measure-
x = distance in direction of heat flow (thickness), in. (m)
ments and Thermal Transmission Properties by Means of
the Heat Flow Meter Apparatus
C 585 Practice for Inner and Outer Diameters of Rigid
4. Summary of Practice
Thermal Insulation for Nominal Sizes of Pipe and Tubing
2 4.1 The procedures used in this practice are based upon
(NPS System)
standard steady-state heat transfer theory as outlined in text-
E 691 Practice for Conducting an Interlaboratory Study to
3 books and handbooks. The computer program combines the
Determine the Precision of a Test Method
functions of data input, analysis, and data output into an
2.2 ANSI Standards:
easy-to-use, interactive computer program. By making the
program interactive, little operator training is needed to per-
This practice is under the jurisdiction of ASTM Committee C16 on Thermal
form fast, accurate calculations.
Insulation and is the direct responsibility of Subcommittee C16.30 on Thermal
4.2 The operation of the computer program follows the
Measurement.
Current edition approved Jan. 27, 1989. Published May 1989. Originally
e1
published as C 680 – 71. Last previous edition C 680 – 82 .
2 4
Annual Book of ASTM Standards, Vol 04.06. Available from American National Standards Institute (ANSI), 25 W. 43rd St.,
Annual Book of ASTM Standards, Vol 14.02. 4th Floor, New York, NY 10036.
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NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
C 680 – 89 (2002)
procedure listed below: this change is generally continuous and can be mathematically
4.2.1 Data Input—The computer requests and the operator
approximated. In the cryogenic region where one or more
inserts information that describes the system and operating components of the air condense, a more detailed mathematical
environment. The data include:
treatment may be required. For those insulations that depend
4.2.1.1 Analysis Identification. on high molecular weight, that is, fluorinated hydrocarbons, for
4.2.1.2 Date.
their insulating effectiveness, gas condensation will occur at
4.2.1.3 Ambient Temperature. higher temperatures and produce sharp changes of conductivity
4.2.1.4 Surface coefficient or ambient wind speed, insula-
in the moderate temperature range. For this reason, it is
tion system surface emittance, and orientation.
necessary to consider the temperature conductivity dependence
4.2.1.5 System Description—Layer number, material, and
of an insulation system when calculating thermal performance.
thicknesses.
The use of a single value thermal conductivity at the mean
4.2.2 Analysis—Once input data is entered, the program
temperature will provide less accurate predictions, especially
calculates the surface coefficients (if not entered directly) and
when bridging regions where strong temperature dependence
the layer resistances, then uses that data to calculate the heat
occurs.
losses and surface temperatures. The program continues to
5.6 The use of this practice by both manufacturers and users
repeat the analysis using the previous temperature data to
of thermal insulations will provide standardized engineering
update the estimates of layer resistance until the temperatures
data of sufficient accuracy for predicting thermal insulation
at each surface repeat with a specified tolerance.
performance.
4.2.3 Once convergence of the temperatures is reached, the
5.7 Computers are now readily available to most producers
program prints a table giving the input data, the resulting heat
and consumers of thermal insulation to permit the use of this
flows, and the inner surface and external surface temperatures.
practice.
5. Significance and Use
5.8 Two separate computer programs are described in this
practice as a guide for calculation of the heat loss or gain, and
5.1 Manufacturers of thermal insulations express the perfor-
surface temperatures, of insulated pipe and equipment systems.
mance of their products in charts and tables showing heat gain
The range of application of these programs and the reliability
or loss per lineal foot of pipe or square foot of equipment
of the output is a primary function of the range and quality of
surface. These data are presented for typical operating tem-
the input data. Both programs are intended for use with an
peratures, pipe sizes, and surface orientations (facing up, down,
“interactive” terminal. With this system, intermediate output
or horizontal) for several insulation thicknesses. The insulation
guides the user to make programming adjustments to the input
surface temperature is often shown for each condition, to
parameters as necessary. The computer controls the terminal
provide the user with information on personnel protection or
interactively with program-generated instructions and ques-
surface condensation. Additional information on effects of
wind velocity, jacket emittance, and ambient conditions may tions, prompting user response. This facilitates problem solu-
tion and increases the probability of successful computer runs.
also be required to properly select an insulation system. Due to
the infinite combinations of size, temperature, humidity, thick-
5.8.1 Program C 608E is designed for an interactive solu-
ness, jacket properties, surface emittance, orientation, ambient
tion of equipment heat transfer problems.
conditions, etc., it is not practical to publish data for each
5.8.2 Program C 608P is designed for interactive solution of
possible case.
piping-system problems. The subroutine SELECT has been
5.2 Users of thermal insulation, faced with the problem of
written to provide input for the nominal iron pipe sizes as
designing large systems of insulated piping and equipment,
shown in Practice C 585, Tables 1 and 3. The use of this
encounter substantial engineering costs to obtain the required
program for tubing-systems problems is possible by rewriting
thermal information. This cost can be substantially reduced by
subroutine SELECT such that the tabular data contain the
both the use of accurate engineering data tables, or by the use
appropriate data for tubing rather than piping systems (Practice
of available computer analysis tools, or both.
C 585, Tables 2 and 4).
5.3 The use of analysis procedures described in this practice
5.8.3 Combinations of the two programs are possible by
can also apply to existing systems. For example, C 680 is
using an initial selector program that would select the option
referenced for use with Procedures C 1057 and C 1055 for burn
being used and elimination of one of the k curve and surface
hazard evaluation for heated surfaces. Infrared inspection or in
coefficient subroutines that are identical in each program.
situ heat flux measurements are often used in conjunction with
5.8.4 These programs are designed to obtain results identi-
C 680 to evaluate insulation system performance and durability
cal to the previous batch program of the 1971 edition of this
on operating systems. This type analysis is often made prior to
practice. The only major changes are the use of an interactive
system upgrades or replacements.
terminal and the addition of a subroutine for calculating surface
5.4 The calculation of heat loss or gain and surface tem-
coefficient.
perature of an insulated system is mathematically complex and
because of the iterative nature of the method, is best handled by 5.9 The user of this practice may wish to modify the data
computers. input and report sections of the computer program presented
5.5 The thermal conductivity of most insulating materials here to fit individual needs. Also, additional calculations may
changes with mean temperature. Since most thermal insulating be desired to include other data such as system costs or
materials rely on enclosed air spaces for their effectiveness, economic thickness. No conflict with this method in making
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
C 680 – 89 (2002)
these modifications exists, provided that the user has demon- composite (multiple-layer) cases and supplemented with pro-
strated compatibility. Compatibility is demonstrated using a vision for heat flow from the outer surface by convection or
series of test cases covering the range for which the new radiation, or both.
method is to be used. For those cases, results for the heat flow 6.3 Equations—Case 1, Slab Insulation:
and surface temperatures must be identical, within the resolu- 6.3.1 Case 1 is a slab of insulation shown in Fig. 1 having
tion of the method, to those obtained using the method width W, height H, and thickness T. It is assumed that heat flow
described herein. occurs only in the thickness of x direction. It is also assumed
5.10 This practice has been prepared to provide input and that the temperature t of the surface at x is the same as the
1 1
output data that conforms to the system of units commonly equipment surface temperature and the time rate of heat flow
used by United States industry. Although modification of the per unit area entering the surface at x is designated q . The
1 1
input/output routines would provide an SI equivalent of the time rate of heat flow per unit area leaving the surfaces at x is
heat-flow results, no such “metric” equivalent is available for q .
the other portions of the program. To date, there is no accepted 6.3.1.1 For the assumption of steady-state (time-
metric dimensions system for pipe and insulation systems for independent) condition, the law of conservation of energy
cyclindrical shapes. The dimensions in use in Europe are the SI dictates that for any layer the time rate of heat flow in must
dimension equivalents of the American sizes, and in addition equal the time rate of heat flow out, i.e., there is no net storage
have different designations in each country. Therefore, due to of energy inside the layer.
the complexity of providing a standardized equivalent of this 6.3.1.2 Taking thin sections of thickness Dx, energy bal-
procedure, no SI version of this practice has been prepared. At ances may be written for these sections as follows:
the time in which an international standardization of piping and Case 1:
insulation sizing occurs, this practice can be rewritten to meet
~WHq! | 2 ~WHq! | 5 0 (1)
x x1Dx
those needs. This system has also been demonstrated to
NOTE 1—The vertical line with a subscript indicates the point at which
calculate the heat loss for bare systems by the inclusion of the
the previous parameter is evaluated. For example: q| reads the time
x+ Dx
pipe/equipment wall thermal resistance into the equation sys-
rate of heat flow per unit area, evaluated at x + Dx.
tem. This modification, although possible, is beyond the scope
6.3.1.3 After dividing Eq 1 by − WHDx and taking the limit
of this practice.
as Dx approaches zero, the differential equation for heat
6. Method of Calculation
transfer is obtained for the one-dimensional case:
6.1 Approach:
~d/dx!q 5 0 (2)
6.1.1 This calculation of heat gain or loss, and surface
6.3.1.4 Integrating Eq 2 and imposing the condition of heat
temperature, requires (1) that the thermal insulation be homo-
flow stability on the result yields the following:
geneous as outlined by the definition of thermal conductivity in
q 5 q 5 q (3)
1 2
Terminology C 168; (2) that the pipe size and equipment
operating temperature be known; (3) that the insulation thick- 6.3.1.5 When the thermal conductivity, k, is a function of
ness be known; (4) that the surface coefficient of the system be
local
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