Page 138 - Estimators Piping Man Hour Manual

Section Two-FIELD FABRICATION 121

PREHEATING

Butt Welds and Any Type of Flange Welds

Carbon Steel, or Alloy Materials
For Temperatures Up to 400 °F

NET MAN HOURS EACH
Standard Extra
Pipe Heavy Pipe SCHEDULE NUMBERS
Size Si OD Sizes & OD Sizes
Ins. 3/8" Thick 1/2" Thick 20 30 40 60 80 100 120 140 160

2 0.2 0.3 __ 0.2 0.3 __ »- 0.5
2-1/2 0.3 0.5 — 0.3 — 0.5 _- 0,8
3 0.5 0.6 -- 0.5 0.6 -- -- 0.7
3-1/2 0.5 0.6 — 0.5 ._ 0.6 .. 0,9
4 0.6 0.7 0.6 0.7 0.9 .. 0.9
— — — —
5 0.7 0.9 0.7 .. 0.9 0.9 .. 1.0
— — —
8 0.8 1.0 0.8 1.0 1.3 1,5
— — — — —
8 0.9 1.3 0.9 0.9 0.9 1.3 1.3 1.8 1.9 2.4 2.5
10 1.3 1.8 1.3 1.3 1.3 1.8 2.0 2.4 2.7 3.3 3.8

12 1.5 2.0 1.5 1.5 1.9 2.2 2.8 3.3 3.8 4.4 5.3
14 OO 1.9 2.5 1.9 1.9 2.2 3.0 3.5 4.4 5.0 5.8 6.6
16 OD 2.2 3.3 2.2 2.2 3.0 3.8 4.5 5.4 6.0 7.3 8.5
18 OO 2.6 3.5 2.6 3.1 4.1 5.0 6.0 7.0 7.9 8.5 10.5
20 OD 3.1 4.1 3.1 4.1 5.2 6.3 7.4 8.7 9.8 11.1 12.9
24 OD 3.7 5.0 3.7 5.3 6.4 7.8 9.3 10.4 11.7 13. 3 15.2

Pipe Thickness: The wall thickness of the material determines the man hours that will apply. For preheating of
double extra strong material, use schedule 160 man hours.
Mitre Welds: For preheating of mitre welds, add 50% to above man hours.
Man Hours: Man hours for preheating are additional to charges for welding operations.
Preheating: For preheating to temperatures above 400°F. but not exceeding 600°F., add 100% to the above man
hours.