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Ch76-I044963.fm Page 377 Tuesday, August 1, 2006 8:30 PM
8:30 PM
1, 2006
Page 377
Ch76-I044963.fm
Tuesday, August
377
377
PRESSURE MONITORING SYSTEM OF
GLAND PACKING FOR A CONTROL VALVE
, Masahiro NAITO 1
1
2
Terunao HIROTA , Ryouji OKUTSU , Kouji IZUMI 2
V Inst. of Environmental Studies, Graduate School of Frontier Science, The University of
Tokyo,7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan,
:
/Yamatake Corporation, 4-1-1 Samukawa-Machi, Kohza-Gun, Kanagawa, 253-0113, Japan

ABSTRACT
In control valves, the sealing characteristics of gland packing has a close relation to the pressure of the
radial direction of the packing, and tightening the packing in the direction of the axis controls the
magnitude of the pressure in radial direction. So far, measurement of this radius direction pressure has
been difficult, involving problems regarding the changes of the radial pressure over time or the
distribution of the pressure.
Thus, in this paper, a method of measuring radial pressure through grease was proposed using a sensor
for measuring the pressure of a fluid, and measurement equipment based on this idea was produced.
First, the validity of this measuring method was evaluated. Next, the action of the piled-up packings in
a bonnet was clarified by applying this measuring method to the system.

KEYWORDS
Sensing systems, Control valve, Gland Packing, Pressure, Grease, Dynamic seal

INTRODUCTION
Currently, the state of packing is managed by experienced and intuitive of safety members, and this
state is distinguished by decomposing control valves. However, inspection by workers is often
inaccurate, and too much inspection time reduces the operating ratio of the plant. Thus, a new
technology dedicated to failure-diagnosis is demanded.

In order to prevent failure, it is necessary to clarify the behavior of the gland packing. The sealing
characteristics of gland packing are strongly affected by the magnitude of the contact pressure between
packing and the stem or the bonnet (=Radial Pressure), and this magnitude is controlled by tightening
the pressure in the direction of the axis (=Axial Pressure) (Fig. 1). Therefore, in order to prevent failure,
it is necessary to clarify the relation between the axial pressure and radial pressure.