ASTM C1129 - 17

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Designation: C1129 −17
Standard Practice for
Estimation of Heat Savings by Adding Thermal Insulation to
Bare Valves and Flanges
1
This standard is issued under the ﬁxed designation C1129; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 The mathematical methods included in this practice
provide a calculational procedure for estimating heat loss or
heat savings when thermal insulation is added to bare valves
and ﬂanges.
1.2 Questions of applicability to real systems should be
resolved by qualiﬁed personnel familiar with insulation sys-
tems design and analysis.
1.3 Estimated accuracy is limited by the following:
1.3.1 The range and quality of the physical property data for
the insulation materials and system,
1.3.2 The accuracy of the methodology used in calculation
of the bare valve and insulation surface areas, and the quality
of workmanship, fabrication, and installation.
1.4 This procedure is considered applicable both for
conventional-type insulation systems and for removable/
reuseable covers. In both cases, for purposes of heat transfer
calculations, the insulation system is assumed to be homog-
enous.
1.5 This practice does not intend to establish the criteria
required in the design of the equipment over which thermal
insulation is used, nor does this practice establish or recom-
mend the applicability of thermal insulation over all surfaces.
1.6 The values stated in inch-pound units are to be regarded
as standard. The values given in parentheses are mathematical
conversions to SI units that are provided for information only
and are not considered standard.
1.7 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 appro-
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use.
2. Referenced Documents
2.1 ASTM Standards:
2
C168 Terminology Relating to Thermal Insulation
C450 Practice for Fabrication of Thermal Insulating Fitting
Covers for NPS Piping, and Vessel Lagging
C680 Practice for Estimate of the Heat Gain or Loss and the
Surface Temperatures of Insulated Flat, Cylindrical, and
Spherical Systems by Use of Computer Programs
C1695 Speciﬁcation for Fabrication of Flexible Removable
and Reusable Blanket Insulation for Hot Service
2.2 ASTM Adjuncts:
3
ADJC0450A Recommended Dimensional Standards for
Fabrication of Thermal Insulating Fitting Covers for NPS
Piping and Vessel Lagging
2.3 American National Standards Institute Standard:
ANSI B16.5 Fittings, Flanges, and Valves
4
3. Terminology
3.1 Deﬁnitions—For deﬁnitions of terms used in this
practice, refer to Terminology C168.
3.2 Symbols:
1
This practice is under the jurisdiction of ASTM Committee C16 on Thermal
Insulation and is the direct responsibility of Subcommittee C16.30 on Thermal
Measurement.
Current edition approved March 1, 2017. Published March 2017. Originally
approved in 1989. Last previous edition approved in 2012 as C1129 – 12. DOI:
10.1520/C1129-17.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
3
Available from ASTM International Headquarters. Order Adjunct No.
ADJADJC0450A. Original adjunct produced in 1976. Adjunct last revised in 2002.
4
Available from American National Standards Institute (ANSI), 25 W. 43rd St.,
4th Floor, New York, NY 10036, http://www.ansi.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
1
 

3.2.1 The following symbols are used in the development of
the equations for this practice. Other symbols will be intro-
duced and deﬁned in the detailed description of the develop-
ment. See Fig. 1 and Fig. 2.
A
B
= outer surface area of the bare valve or ﬂange (does not
include the wheel and stem of the valve), ft
2
(m
2
).
A
I
= surface area of the insulation cover over the valve or
ﬂange, ft
2
(m
2
).
C= distance from the center-line axis of the pipe (to which
the valve is attached) to the uppermost position of the
valve that is to be insulated (recommended to be
below the gland seal), ft (m).
D
F
= the valve ﬂange and the bonnet ﬂange outer diameter
(assumed equal), ft (m).
D
P
= the actual diameter of the pipe, ft (m).
L
V
= overall length of the valve, ﬂange to ﬂange, ft (m).
T= thickness of the valve ﬂange and of the bonnet ﬂange,
ft (m).
q
B
= time rate of heat loss per unit area from the bare valve
or ﬂange surface, Btu/h·ft
2
(W/m
2
).
q
I
= time rate of heat loss per unit area from the insulation
surface, Btu/h·ft
2
)(W/m
2
).
Q
B
= time rate of heat loss from the bare valve or ﬂange
surface, Btu/h (W).
Q
I
= time rate of heat loss from the insulated surface, Btu/h
(W).
4. Summary of Practice
4.1 The procedures for estimating heat loss used in this
practice are based upon standard steady-state heat transfer
theory as outlined in Practice C680 (or programs conforming to
it such as 3E Plus
5
). Practice C680 and 3E plus are used to
estimate the heat loss per unit surface area for the particular
conditions and for all conﬁgurations, both bare and insulated.
4.2 The procedures for estimating surface areas used in this
practice are based on standard geometric logic: for a bare valve
or ﬂange, the contours of the metal surface are considered. For
an insulated valve or ﬂange, the fabricated shape of the ﬁnished
insulation system is considered.
4.3 Data Input:
4.3.1 Total bare surface area and total insulation surface
area of the valve or ﬂange,
4.3.2 Service and ambient temperatures,
4.3.3 Wind speed,
4.3.4 Surface emittance values
4.3.5 Insulation thickness and type, and
4.3.6 Number of service hours per year.
4.4 System Description—Insulation thickness, insulation
type, bare valve or ﬂange surface emittance, insulation surface
emittance.
4.5 Analysis—Once input data is entered, the program
calculates the surface coefficients (if not entered directly), the
insulation resistance, the bare metal heat loss per unit area, and
the insulation surface heat loss per unit area. The rate of heat
loss per unit area is computed by Practice C680 for the
appropriate diameter. For bare gate valves, the particular
surface area can be taken from a look-up table. Table 1 and
Table 2 give these areas for typical (ANSI Class 150, 300, 600,
and 900) ﬂanged gate valves and ﬂanges. If these valves are not
considered sufficiently accurate for the particular valves or
ﬂanges being considered, those areas can be calculated using
Eq 1 (see Fig. 1) for bare ﬂanges and Eq 2 (see Fig. 2) for bare
gate valves. Similar equations can be developed for other types
of valves and ﬂanges. For the insulation on the valves and the
ﬂanges, the outer surface area can be obtained either from
Table 3 and Table 4 for insulation thickness up to 4 in. or from
the insulation fabricator or contractor.
5. Signiﬁcance and Use
5.1 Manufacturers of thermal insulation for valves typically
express the performance of their products in charts and tables
showing heat loss per valve. These data are presented for both
bare and insulated valves of different pipe sizes, ANSI classes,
insulation types, insulation thicknesses, and service tempera-
tures. Additional information on effects of wind velocity, jacket
emittance, bare valve emittance, and ambient conditions are
also required to properly select an insulation system. Due to the
inﬁnite combination of pipe sizes, ANSI classes, insulation
types and thicknesses, service temperatures, insulation cover
geometries, surface emittance values, and ambient conditions,
it is not possible to publish data for each possible case.
5
Available from the North American Insulation Manufacturers Association for a
free download. http//:www.pipeinsulation.org.
FIG. 1 Equation 1 for a for the Surface Area of Bare Valve, A
B
V
=[D
P
(L
V
+2L
F
+(C−D
P
/2)−6T)+1.5(D
F
2
−D
P
2
)+6D
F
T]π(Ref.
3)
FIG. 2 Equation 2 for the surface area of a Bare Flange, A
BF
[D
P
2L
F
+(D
F
2
–D
P
2
)/2+2D
F
T]
C1129 − 17
2
 

5.2 Users of thermal insulation for piping systems faced

with the problem of designing large systems of insulated

piping, encounter substantial engineering costs to obtain the

required thermal information. This cost can be substantially

reduced by both the use of accurate engineering data tables, or

by the use of available computer analysis tools, or both.

5.3 The use of this practice by the manufacturer, contractor,

and users of thermal insulation for valves and ﬂanges will

provide standardized engineering data of sufficient accuracy

and consistency for predicting the savings in heating energy

use by insulating bare valves and ﬂanges.

5.4 Computers are now readily available to most producers

and consumers of thermal insulation to permit use of this

practice.

5.5 The computer program in Practice C680 has been

developed to calculate the heat loss per unit length, or per unit

surface area, of both bare and insulated pipe. With values for

bare valve or ﬂange surface areas, heat loss can be estimated.

By estimating the outer insulation surface area from an

insulation manufacturer’s or contractor’s drawings, the heat

loss from the insulation surface can likewise be calculated by

taking the product of heat loss per unit area (from programs

conforming to Practice C680) and the valve or ﬂange insulation

surface area. The area of the uninsulated surfaces also will need

to be considered.

5.6 The use of this practice requires that the valve or ﬂange

insulation system meets either Speciﬁcation C1695 for

removeable/reuseable or the Adjunct to Practice C450

for

insulation fabricated from rigid board and pipe insulation.

6. Calculation

6.1 This calculation of heat gain or loss requires the

following:

6.1.1 The thermal insulation shall be assumed to be homog-

enous as outlined by the deﬁnition of thermal conductivity in

Terminology C168.

6.1.2 The valve or ﬂange size and operating temperature

shall be known.

6.1.3 The insulation thickness shall be known.

6.1.4 Values of wind speed and surface emittance shall be

available to estimate the surface coefficients for both the bare

surface and for the insulation.

6.1.5 The surface temperature in each case shall be assumed

to be uniform.

6.1.6 The bare surface dimensions or area shall be known.

6.1.7 The outer surface area of the insulation cover can be

estimated from drawings or ﬁeld measurements.

6.1.8 Practice C680 or other comparable methodology shall

be used to estimate the heat loss from both bare and insulated

surfaces.

TABLE 1 Calculated Surface Areas of Bare Valves using Eq 1 (Ref3)

ANSI Class

NPS, in. 150 300 600 900

)ft

)

2 2.21 (0.205) 2.94 (0.273) 2.94 (0.273) 5.20 (0.483)

⁄

2.97 (0.276) 3.51 (0.326) 3.91 (0.363) 6.60 (0.613)

3 3.37 (0.313) 4.39 (0.408) 4.69 (0.436) 6.50 (0.604)

4 4.68 (0.435) 6.06 (0.563) 7.64 (0.710) 9.37 (0.870)

6 7.03 (0.653) 9.71 (0.902) 13.03 (1.210) 15.80 (1.468)

8 10.30 (0.957) 13.50 (1.254) 18.40 (1.709) 23.80 (2.211)

10 13.80 (1.284) 18.00 (1.672) 26.50 (2.462) 32.10 (2.982)

12 16.10 (1.496) 24.10 (2.239) 31.90 (2.964) 41.90 (3.893)

14 22.80 (2.118) 32.50 (3.019) 39.70 (3.688) 48.20 (4.978)

16 27.60 (2.564) 39.30 (3.651) 50.50 (4.691) 57.00 (5.295)

18 31.70 (2.945) 49.40 (4.589) 59.80 (5.555) 69.70 (6.475)

20 37.70 (3.502) 59.10 (5.490) 71.30 (6.624) ......

24 49.10 (4.561) 83.50 (7.757) 95.10 (8.835) ......

30 72.20 (6.707) 123.30 (11.46) 141.70 (13.6) ......

36 107.30 (9.968) 164.00 (15.24) 199.00 (18.49) ......

TABLE 2 Calculated Flange Pair Surface Areas using Eq 2

Bare surface areas in square feet (square meters) for ANSI Classes 150, 300, 600, and 900

NPS, in. 150 300 600 900

)ft

)

2 0.71 0.066 0.84 0.078 0.88 0.081 1.54 0.143

3 1.06 0.099 1.32 0.122 1.36 0.127 1.85 0.172

4 1.44 0.133 1.83 0.170 2.23 0.208 2.64 0.245

6 2.04 0.190 2.72 0.252 3.60 0.334 4.37 0.406

8 2.92 0.271 3.74 0.348 4.89 0.454 6.40 0.595

10 3.68 0.342 4.80 0.446 6.93 0.643 8.47 0.787

12 5.01 0.465 6.34 0.589 7.97 0.740 10.43 0.969

14 6.15 0.571 7.90 0.734 9.16 0.851 11.59 1.077

16 7.19 0.668 9.25 0.859 11.49 1.067 13.34 1.239

20 9.40 0.873 12.50 1.161 15.18 1.411 19.12 1.776

24 11.82 1.099 16.23 1.507 19.30 1.793 28.18 2.618

C1129 − 17

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摘要：

ASTM C1129 - 17 是由美国材料与试验协会（ASTM）发布的关于建筑用预制柔性泡沫隔热材料的标准规范，该标准详细规定了适用于管道、设备及建筑围护结构的闭孔弹性泡沫隔热材料的技术要求、测试方法和性能指标。文档内容涵盖了材料的密度、热导率、吸水率、燃烧特性及尺寸稳定性等关键参数，旨在确保隔热材料在低温和中温应用中的可靠性与能效表现。此标准对于暖通空调系统、工业管道保温及冷库建设等领域的工程师、设计师和施工方具有重要参考价值，有助于优化建筑节能设计并满足材料合规性要求。

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