GE Oil & Gas T5, Руководство по установке

Страница: 30 / 77

T5 Flare Gas Transducer Installation Guide 21
Chapter 1. Installing Pipe Nozzles
1.3.4 Installing the First Welding Boss
1. Before welding the first boss, you must add another scribe line known as the oblique center line . The oblique
center line compensates for the slope or oblique of the boss. The oblique center line is offset from the true
center (vertical) scribe line marked earlier by a distance of
X
, which is dependent on the pipe outside diameter
as follows:
where, D = pipe outside diameter
d = welding boss outside diameter (1.660 in.)
Table 2 below shows values of
X
for various pipe sizes.
2. Scribe the oblique center line on the pipe at the calculated distance from the true center line. The oblique center
line should be marked on the side of the true center line that is closer to the second nozzle location.
Table 2: X Values for Various Pipe Sizes
Pipe Size
X Dimensions NPS (DN) O.D.
6 in. (150 mm) 6.625 in. (168 mm) 0.106 in. (2.69 mm)
8 in. (200 mm) 8.625 in. (219 mm) 0.081 in. (2.06 mm)
10 in. (250 mm) 10.750 in. (273 mm) 0.064 in. (1.62 mm)
12 in. (300 mm) 12.750 in. (324 mm) 0.054 in. (1.37 mm)
14 in. (350 mm) 14.000 in. (356 mm) 0.049 in. (1.24 mm)
X D 2
⁄
d 2
⁄
sin
-1
d D
⁄ ( ) [ ]
tan
-----------------------------------------
– =
True Center Line
Oblique Center Line
Side View