Thermos Index
Thermal Insulation

Thermal Insulation

Heat Loss from bare steel pipe (worst case scenario).....
Heat Loss from insulated pipe- (100-200 deg.C. Contents).....
Heat Loss from insulated pipe- (300-400 deg.C. Contents).....
Heat Loss from insulated pipe- (500-600 deg.C. Contents).....
Heat Loss from insulated pipe- (700 deg. C. Contents).....



Table showing heat loss from bare black steel pipes


Note: The conditions applying to this table are.
  • Horizontal pipes
  • Ambient Air at 20 deg. C
  • Emissivity value used = 0,9
  • Ambient Ambient air Velocity = 0 m/s
  • Pipe contents temperature as shown

Pipe OD Heat Loss from black steel bare pipe (W /m - W/m2 from flat )
Pipe Temperature ( Deg. C)
50 100 150 200 250 300 350 400 450 500 550 600 650 700
17,2 23 78 150 241 353 491 658 859 1099 1384 1720 2113 2571 3100
21,3 27 93 180 290 427 594 798 1043 1337 1687 2099 2583 3146 3798
26,9 33 114 221 356 525 732 985 1291 1658 2095 2611 3217 3923 4742
33,7 41 139 269 435 641 897 1209 1588 2042 2585 3226 3979 4859 5878
42,4 50 169 329 532 788 1104 1491 1961 2527 3203 4004 4945 6045 7320
48,3 56 190 369 598 885 1242 1679 2212 2853 3619 4527 5595 6843 8292
60,3 68 230 448 728 1081 1519 2058 2715 3508 4456 5582 6908 8458 10258
76,1 83 283 551 896 1333 1878 2550 3370 4360 5548 6958 8621 10566 12827
88,9 95 324 632 1031 1535 2165 2943 3894 5044 6424 8064 9998 12263 14897
101,6 107 365 712 1162 1733 2447 3330 4410 5718 7287 9155 11358 13940 16942
114,3 119 405 791 1292 1929 2726 3714 4922 6387 8147 10241 12713 15609 18979
139,7 142 484 947 1549 2316 3279 4474 5939 7716 9853 12399 15406 18932 23036
168,3 167 571 1119 1833 2746 3894 5321 7072 9200 11760 14812 18420 22653 27582
219,1 212 722 1419 2330 3498 4971 6806 9063 11809 15117 19065 23736 29220 35609
273,0 258 880 1731 2848 4283 6098 8362 11152 14550 18647 24221 30135 37067 45134
323,9 301 1027 2021 3331 5016 7151 10254 13667 17813 22798 28737 35754 43978 53549
Flat 285 1212 2405 3949 5897 8317 11286 14890 19226 24396 30515 37700 46081 55794




Table showing heat loss from insulated pipes (100 deg.C and 200 deg C contents temp)


Note: The conditions applying to this table are.
  • Horizontal pipes
  • Ambient Air at 20 deg. C
  • Emissivity value used = 0,05
  • Ambient air Velocity = 0 m/s
  • Pipe Contents temp as shown
The basis used for determining the insulation thickness is to minimise heat loss on a sound economic basis.

  Pipe contents temperature = 100 Deg.C Pipe contents temperature = 200 Deg.C
Pipe OD Insulation Thickness (mm) Heat Loss Insulation Thickness (mm) Heat Loss
  k=0,02 k=0,03 k=0,04 k=0,05 k=0,06 (W/m) k=0,03 k=0,04 k=0,05 k=0,06 k=0,07 (W/m)
17,2 11 22 40 72 125 10,4 20 36 63 106 176 24,8
21,3 12 24 44 76 128 11,1 22 40 67 109 176 26,5
26,9 14 27 47 78 128 12,1 25 43 71 113 176 28,6
33,7 15 29 50 80 128 13,2 28 47 76 118 179 30,8
42,4 17 32 53 83 128 14,5 32 52 81 123 183 33,3
48,3 18 33 55 85 129 15,3 34 55 84 126 185 34,9
60,3 20 36 58 88 130 16,8 37 60 90 132 189 37,9
76,1 23 39 62 92 131 18,7 41 64 95 136 191 41,8
88,9 24 42 65 94 133 20,1 44 68 100 141 195 44,5
101,6 26 45 67 96 134 21,5 47 71 103 144 197 47,2
114,3 27 48 69 98 136 22,8 49 74 106 147 198 49,9
139,7 29 49 72 101 137 25,4 53 79 111 152 202 54,8
168,3 31 52 77 107 143 27,8 57 85 118 159 209 59,6
219,1 34 56 81 110 145 32,5 63 92 126 167 216 68,1
244,5 35 57 82 112 146 34,8 65 94 129 169 217 72,6
273,0 37 59 85 114 149 37,1 68 98 133 174 222 76,6
323,9 38 61 87 117 150 41,5 71 102 138 179 226 84,5
355,6 39 62 89 118 151 44,2 73 105 141 181 228 89,4
406,4 41 65 91 121 153 48,2 76 107 143 183 229 97,5
457,0 42 66 92 122 154 52,5 78 110 146 186 233 105,3
508,0 43 68 95 124 157 56,2 80 113 149 189 237 112,3
610 + 49 77 107 141 177 59,4 89 125 167 211 260 120,6

Note: The heat transfer for the 610mm pipe can be used with reasonable accuracy for horizontal plates with the same surface areas as the mean area of the insulated pipes = L.π (D2 - D1) /ln(D2/D1)





Table showing heat loss from insulated pipes (300 deg.C and 400 deg C contents temp.)


Note: The conditions applying to this table are.
  • Horizontal pipes
  • Ambient Air at 20 deg. C
  • Emissivity value used = 0,05
  • Ambient air Velocity = 0 m/s
  • Pipe Contents temp as shown
The basis used for determining the insulation thickness is to minimise heat loss on a sound economic basis.

  Pipe contents temperature = 300 Deg.C Pipe contents temperature = 400 Deg.C
Pipe OD Insulation Thickness (mm) Heat Loss Insulation Thickness (mm) Heat Loss
  k=0,03 k=0,04 k=0,05 k=0,06 k=0,07 (W/m) k= 0,04 k= 0,05 k= 0,06 k= 0,07 k= 0,08 (W/m)
17,2 23 43 75 129 218 36,5 33 56 92 148 236 55,3
21,3 26 46 79 132 218 38,9 36 60 96 151 238 58,9
26,9 29 51 84 137 218 41,8 41 65 96 151 238 63,0
33,7 32 55 90 141 219 45,0 45 71 108 163 241 67,6
42,4 36 60 96 148 223 48,5 51 78 118 173 251 72,2
48,3 39 64 100 152 227 50,6 54 83 123 179 256 75,1
60,3 43 70 108 161 235 54,5 60 91 133 189 267 80,5
76,1 48 76 114 167 237 59,7 66 98 140 196 270 87,8
88,9 51 80 119 171 241 63,5 70 103 145 201 273 93.,4
101,6 53 83 122 173 240 67,5 74 107 150 204 274 98,7
114,3 56 87 126 177 242 71,1 77 111 153 207 276 120,9
139,7 61 93 134 185 250 77,3 84 119 163 217 285 112,5
168,3 67 100 142 194 259 83,6 92 128 174 229 297 120,9
219,1 73 108 151 202 264 95,4 100 139 185 240 308 136,9
244,5 76 112 154 206 267 101,1 105 144 191 246 315 143,9
273,0 80 116 160 212 273 106,5 109 149 196 251 319 152,1
323,9 84 121 165 216 275 117,5 114 154 200 257 321 167,6
355,6 85 123 166 217 277 117,5 117 158 204 262 325 175,8
406,4 89 127 170 220 280 135,2 121 162 211 266 327 190,5
457,0 92 131 175 226 286 144,5 126 170 218 272 333 203,1
508,0 94 134 181 230 287 154,9 130 173 222 275 336 216,7
610 + 100 147 195 249 308 168,0 141 186 236 292 354 237,2

Note: The heat transfer for the 610mm pipe can be used with reasonable accuracy for horizontal plates with the same surface areas as the mean area of the insulated pipes = L.π (D2 - D1) /ln(D2/D1)





Table showing heat loss from insulated pipes (500 deg.C and 600 deg C)


Note: The conditions applying to this table are.
  • Horizontal pipes
  • Ambient Air at 20 deg. C
  • Emissivity value used = 0,05
  • Ambient air Velocity = 0 m/s
  • Pipe Contents temp as shown
The basis used for determining the insulation thickness is to minimise heat loss on a sound economic basis.

  Pipe contents temperature = 500 Deg.C Pipe contents temperature = 600 Deg.C
Pipe OD Insulation Thickness (mm) Heat Loss Insulation Thickness (mm) Heat Loss
  k= 0,05 k= 0,06 k= 0,07 k= 0,08 k= 0,09 (W/m) k= 0,06 k= 0,07 k= 0,08 k= 0,09 k= 0,10 (W/m)
17,2 43 69 107 165 252 77,2 42 62 90 130 186 112,1
21,3 48 74 113 170 253 81,9 47 67 96 136 191 118,7
26,9 53 81 121 178 260 87,2 52 74 104 144 199 126,4
33,7 59 88 128 185 265 93,1 57 79 110 149 202 135,8
42,4 65 95 136 193 270 100,0 65 90 123 164 220 143,3
48,3 69 100 142 199 276 103,9 70 95 129 172 228 148,6
60,3 77 110 154 213 290 110,8 78 101 141 186 242 158,3
76,1 84 118 163 220 295 120,5 85 113 150 194 250 172,0
88,9 90 125 170 228 301 127,3 91 121 158 203 258 181,4
101,6 94 130 179 235 305 141,2 97 127 164 210 265 190,2
114,3 98 134 179 235 305 141,2 101 132 170 215 270 199,2
139,7 107 144 191 248 317 152,0 111 143 182 228 283 214,2
168,3 116 155 203 260 334 163,2 121 155 195 243 302 229,1
219,1 127 168 216 276 345 183,6 134 170 211 263 320 255,7
244,5 133 174 223 284 353 192,4 139 176 221 270 327 268,2
273,0 138 181 228 292 361 202,1 146 184 230 280 338 280,4
323,9 144 189 239 297 364 221,6 154 193 237 287 343 306,9
355,6 149 194 244 302 368 232,6 160 200 244 294 351 320,4
406,4 154 200 251 308 373 250,2 165 204 248 297 352 347,0
457,0 161 206 256 313 376 267,6 172 213 258 308 363 366,7
508,0 165 210 261 317 380 284,7 178 220 265 315 370 387,9
610 + ** 180 228 281 340 405 308,6 195 239 287 340 397 418,6

Note: The heat transfer for the 610mm pipe can be used with reasonable accuracy for horizontal plates with the same surface areas as the mean area of the insulated pipes = L.π (D2 - D1) /ln(D2/D1)





Table showing heat loss from insulated pipes (700 deg C contents temp)


Note: The conditions applying to this table are.
  • Horizontal pipes
  • Ambient Air at 20 deg. C
  • Emissivity value used = 0,05
  • Ambient air Velocity = 0 m/s
  • Pipe Contents temp as shown
The basis used for determining the insulation thickness is to minimise heat loss on a sound economic basis.

  Pipe contents Pipe contents temperature = 700 Deg.C
Pipe OD Insulation Thickness (mm) Heat Loss
  k= 0,07 k= 0,08 k= 0,09 k= 0,10 k= 0,11 (W/m)
17,2 52 73 103 145 202 141,1
21,3 56 79 110 152 209 149,1
26,9 63 87 119 162 218 158,3
33,7 68 93 125 167 221 169,9
42,4 78 105 139 184 240 179,2
48,3 83 111 146 191 248 185,9
60,3 93 123 160 206 265 197,4
76,1 102 132 170 216 273 213,8
88,9 109 140 179 226 283 224,9
101,6 115 147 186 233 290 235,9
114,3 119 152 191 238 300 247,0
139,7 131 165 206 254 315 264,6
168,3 143 179 221 274 333 282,0
219,1 158 195 242 293 352 314,0
244,5 164 204 250 302 361 328,6
273,0 169 214 260 312 371 343,9
323,9 182 223 268 320 377 375,0
355,6 186 227 272 323 380 394,6
406,4 194 236 281 333 389 421,5
457,0 203 245 292 343 400 445,7
508,0 210 253 300 351 408 470,5
610 + 230 275 325 380 439 506,1


Useful Links
  1. The Control of Asbestos Regulations 2006 .. Very important document related to asbestos insulation
  2. Wikipedia- Thermal Insulation.. A very useful reference source
  3. 3.3 Thermal insulation and condensation.. British Gypsum- Lots of information regarding building insulation.
  4. Thermoflece.. Natural Wool Insulation
  5. Hyperphysics -Heat Transfer.. Very Clear Notes


Thermos Index
Thermal Insulation

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