Pipes - Bare Surface Heat Loss

Heat loss from uninsulated pipes with bare surfaces at still-air conditions and air temperature 70 °F (21 °C). Emissivity coefficient of the surface is 0.95.

Pipe Diameter (inches)	Surface Temperature (°F)	Heat Loss (BTU/hr/ft)
0.5	100	1.2
0.5	150	3.8
0.5	200	7.5
0.5	250	12.8
1	100	1.9
1	150	6
1	200	11.8
1	250	20.2
1.5	100	2.5
1.5	150	7.9
1.5	200	15.5
1.5	250	26.5
2	100	3.2
2	150	10.1
2	200	19.8
2	250	33.8
3	100	4.5
3	150	14.2
3	200	27.9
3	250	47.6
4	100	5.8
4	150	18.3
4	200	36
4	250	61.5