Panametrics T17, Руководство по установке, Страница: 23 / 76

Model T17 Installation Guide 11
Chapter 2. Installing Pipe Nozzles
2.2.4 Installing the First Welding Boss, Diametrical
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 angle 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 1 below shows values of X for various pipe sizes.
2. Scribe the oblique center line on the pipe at the prescribed 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.
Pipe
X Dimensions NPS (DN) O.D.
12 in. (300 mm) 12.75 in. 0.054 in. (1.37 mm)
14 in. (350 mm) 14.00 in. 0.049 in. (1.24 mm)
16 in. (400 mm) 16.00 in. 0.043 in. (1.09 mm)
18 in. (450 mm) 18.00 in. 0.038 in. (0.97 mm)
20 in. (500 mm) 20.00 in. 0.035 in. (0.89 mm)
22 in (600 mm) 22.00 in. 0.032 in. (0.81 mm)
24 in. (650 mm) 24.00 in. 0.029 in. (0.74 mm)
26 in. (700 mm) 26.00 in. 0.027 in. (0.68 mm)
X D 2

d 2

sin
-1
d D      tan
----------------------------------------- – =
True Center Line
Oblique Center Line
Side View