HTML has links - PDF has Authentication
51-11C-40328  <<  51-11C-403281 >>   51-11C-40329

PDFWAC 51-11C-403281

Table C403.2.9Minimum pipe insulation thickness.

Table C403.2.9
Minimum Pipe Insulation Thickness (thickness in inches)a
Fluid Operating Temperature Range and Usage (°F)
Insulation Conductivity
Nominal Pipe or Tube Size (inches)
Conductivity
Btu • in. /(h • ft2 • °F)b
Mean
Rating
Temperature, °F
<  1
1 to <  1-1/2
1-1/2 to <  4
4 to <  8
≥  8
˃  350
0.32 - 0.34
250
4.5
5.0
5.0
5.0
5.0
251 - 350
0.29 - 0.32
200
3.0
4.0
4.5
4.5
4.5
201 - 250
0.27 - 0.30
150
2.5
2.5
2.5
3.0
3.0
141 - 200
0.25 - 0.29
125
1.5
1.5
2.0
2.0
2.0
105 - 140
0.21 - 0.28
100
1.0
1.0
1.5
1.5
1.5
40 - 60
0.21 - 0.27
75
0.5
0.5
1.0
1.0
1.0
< 40
0.20 - 0.26
75
0.5
1.0
1.0
1.0
1.5
a
For piping smaller than 1-1/2 inch (38 mm) and located in partitions within conditioned spaces, reduction of these thicknesses by 1 inch (25 mm) shall be permitted (before thickness adjustment required in footnote b) but not to a thickness less than 1 inch (25 mm).
b
For insulation outside the stated conductivity range, the minimum thickness (T) shall be determined as follows:
T
=
r{(1 + t/r)K/k - 1}
Where:
 
 
T
=
Minimum insulation thickness,
r
=
Actual outside radius of pipe,
t
=
Insulation thickness listed in the table for applicable fluid temperature and pipe size,
K
=
Conductivity of alternate material at mean rating temperature indicated for the applicable fluid temperature (Btu × in/h × ft2 × °F) and
k
=
The upper value of the conductivity range listed in the table for the applicable fluid temperature.
c
For direct-buried heating and hot water system piping, reduction of these thicknesses by 1-1/2 inches (38 mm) shall be permitted (before thickness adjustment required in footnote b but not to thicknesses less than 1 inch (25 mm).
[Statutory Authority: RCW 19.27A.025, 19.27A.160, and 19.27.074. WSR 16-03-072, § 51-11C-403281, filed 1/19/16, effective 7/1/16. Statutory Authority: RCW 19.27A.020, 19.27A.025 and chapters 19.27 and 34.05 RCW. WSR 13-04-056, § 51-11C-403281, filed 2/1/13, effective 7/1/13.]
Site Contents
Selected content listed in alphabetical order under each group