Tank Spud Mounting Method - YOKOGAWA DPharp EJXC80A User Manual

4.7.3 Tank Spud Mounting Method

A tank spud is used to joint a tank and an extended
diaphragm type of level transmitter.
It is imperative for sanitary use that the contact
parts of the transmitter and the tank are securely
and tightly sealed in order to avoid the process fluid
spouting and the decomposition by stagnant fluid.
The construction of the tank spud using a O-ring
eliminates the clearance between the contact parts
and ensures the tightness.
Tank spud
in Tank
(A)
Transmitter
body
O-ring
Tank spud
(Detail of A)
Figure 4.13 Details of Transmitter Mounting
 Welding
When welding a tank spud to a tank, take great care
not to change its shape by heat. The deformation of
the shape eventually makes a dead space between
the transmitter and the tank spud, resulting in the
process fluid spouting and the decomposition the
coupling by stagnant fluid.
 Mounting Position
Set the center of the tank spud to a level at least
50mm above the minimum liquid level (zero point).
IMPORTANT
• Clean thoroughly the tank after the welding
the tank spud to the hole on a tank.
• Be sure that the surface is finished smoothly
by using a grinder except the hole is made
by the machinery cutting.
 Mounting Direction
Fit the tank spud onto the tank so that the drain
outlet faces downward. Then carry out the
temporary welding at four points outside the spud,
making sure to keep the boundary of the inside
surface of the tank wall and spud flat. Also, set the
spud vertical against the tank wall, in order for the
transmitter to be installed correctly.
Welding
Transmitter
side
ISO Clamp
Figure 4.14
Tank
 Welding method and Cautions
F0413.ai
<4. Installation>
Tank spud
Minimam liquid level
50mm
Mounting Tank Spud
• Welding work should start with the inside of
tank, then continue to outside.
• Before starting the welding work, cool the
welding part with dry ice and so on. The welded
part should be cooled down one welding part
after another.
• Set the welding heat level as low as possible to
avoid the deformation of the spud.
• Since the tank spud materials used are
SUS304, SUS316, and SUS316L, use the
welding stick material as follows;
Covered arc welding: D316L
Tig or Mig welding: Y316L
• Take care not to damage the O-ring sealing
part.
4-8
Welding
Center of tank spud
Drain hole
Tank
F0414.ai
IM 01C25W01-01EN