Chemical Engineering October 2010 - 35

Table 1. Physical ProPerTies of some insulaTion maTerials, wiTh asTm maTerial sTandards,
TyPically used for above ambienT service in cPi faciliTies
mineral
fiber
pipe
ASTM Material Standard
Max. Use Temperature, °F
Thermal conductivity at 200 °F
mean1
C547,
Type I
850
0.31
Thermal conductivity at 400°F mean1 0.51
Thermal conductivity at 600°F mean1 0.64
Compressive resistance, min.,
lbf/in.2 (C165)
Density, lbm/ft3 (C167)
Flexural strength, min., lbf/in.2
(C201)
pH
Surface burning characteristics
(E84)3
Non-combustible (E136)
Contains corrosion inhibitors2
mineral
fiber
pipe
C547,
Type II,
III, & V
1,200
0.31
0.45
0.65
N/A N/A
Not
stated
Not
stated
mineral
fiber
pipe
C547,
Type IV
mineral
fiber blanket
C553,
Type
VII
1,000 1,200
0.31
0.34
0.45
0.65
0.55
0.81
mineral
fiber board
C612, Type
IV, A, B
1,200
calcium
silicate
pipe & block
Perlite
pipe &
block
C533, Type I C610
1,200
0.30 to 0.34 0.45
0.42 to 0.55 0.55
0.63
0.66
N/A Not stated 0.347 at
10%
Not
stated
3 to 6 6 to 8 3 to 6 Not stated Not stated 15 max
Not stated Not stated 50
8 to 9.5 8 to 9.5 8 to 9.5 8 to 9.5 8 to 10 9 to 11.5
25/50 25/50 25/50 25/50
25/50
Not
stated
No
Not
stated
No
Not
stated
0/0
Not stated Not stated Non-combustible
No
No
No
Yes
1,200
0.55
0.66
0.80
100 at 5% 60 @ 5%
10 to 14
45
9 to 11
0/5
Non-combustible
Yes
Notes:
1. Thermal conductivity values are in units of Btu·in./h·ft2·°F Pipe insulation is tested per ASTM C335 and blanket, board, and block insulation
is tested per ASTM C177
2. Not included in the referenced ASTM material specifications
3. Flame spread index / Smoke developed index
Pre-formed pipe insulation
multiple layer construction
Mitered
segment
Typical fitting core
End
overlap
Throat
Neutral
Crimp
zone
Mitered insulation elbow
oversized application
Edge
overlap
Heel
Brad
zone
Figure 2. This diagram shows the correct way to install
a double-layer insulation system for use at process temperatures
greater than 500°F. Note that both the lap joints
and butt joints are staggered to prevent the occurrence of a
direct path between the outer metal jacket and the inner, hot
pipe surface (Source: National Commercial & Industrial Insulation
Standards, 5th ed., 1999, Plate No. 1)
of application, in most applications
there is adequate clearance for several
inches of insulation. When space
for insulation is not available, then a
material of lower thermal conductivity
can be selected.
Every type of insulation has different
properties. A list of some properties,
for several insulations commonly
used in CPI facilities at above ambient
temperatures, is given in Table 1 (with
Neutral
Throat
Section
Crimp
Bead
Figure 3. This figure shows the correct way to install a single or
double layer insulation system on a 90-deg, long radius elbow on a
high temperature line. Note the use of insulation miters and sheet
metal gores (Source: National Commercial & Industrial Insulation
Standards, 5th Edition, 1999, Plate No. 11)
values for each taken from the listed
ASTM material standard [1]).
Reviewing these properties, it is
apparent that there are significant
differences between these insulation
materials. For example, while calcium
silicate has greater thermal conductivity
values at given mean temperatures,
and has greater density than
most of the mineral fiber materials,
it also has very high compressive-resistance
and flexural-strength values
(and these values are not in the ASTM
standards for the mineral fiber materials
because, in comparison, they are
probably not sufficiently high to merit
being listed). Furthermore, all calcium
silicate and perlite insulation materials
are rated as non-combustible, when
tested per ASTM E136, whereas some
of the mineral fiber materials are and
some are not; hence, this property is
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Chemical Engineering October 2010

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