The 14th Symposium on Accelerator Science and Technology, Tsukuba, Japan, November 2003

DEVELOPMENT OF A RADIAL COMPRESSED SEALAND ITS REMOTE HANDLING DEVICES
Y. Yamanoi*, K. Agari, M. Ieiri, Y. Kato, E. Kusano, M. Minakawa, H. Noumi, Y. Sato, Y. Suzuki,
H. Takahashi, M. Takasaki, K.H. Tanaka, Y. Yamada,
KEK, High Energy Accelerator Research Organization,
1-1 Oho, Tsukuba, Ibaraki, 305-0801 Japan
M. Tsuchiya, R. Horikoshi, IHI, Ishikawajima-Harima Heavy Industries Co., Ltd.,
1 Shin-Nakahara, Isogo, Yokohama 235-8501 Japan
K. Imai, N. Watanabe, M. Ota, Usui Kokusai Sangyo Kaisha, Ltd.,131-2 Nagasawa, Shimizu, Sunto-Gun, Shizuoka, 411-8610 Japan
Abstract
This paper reports the design of a radial compressed
seal and its remote handling flange used in the NP-hall of
J-PARC. This facility will be handled a high intensity
proton beam of 3x1014ppp accelerated by 50GeV. The
power of a primary proton beam will be about 100 times
greater than the currently slow extraction facility at KEK
12GeV-PS. The radial seal ordinary used as the seal ofhigh viscous fluid was developed as a new flange system
for a connection of vacuum beam pipes. Presently twoflange devices were developed by each fastening
mechanisms. The sealing capacity of the connecting
device is reached with <10-10 Pa.m3/sec.

1. INTRODUCTION
The High Energy Accelerator Research Organization(KEK) and the Japan Atomic Energy Research Institute(JAERI) is jointly constructed the High Intensity Proton
Accelerator Facility (J-PARC) in Tokai, Japan [1]. The
facility of this project will be planed the counter
experimental hall called the NP-hall for nuclear physics
and high-energy particle physics. The primary proton
beam will be extracted out to the NP-hall as slow
extraction mode with 0.7s pulse width, 3.27s cycle. This
NP-hall has been designed to handle a primary proton
beam of up to 3x1014 ppp (protons per pulse). The powerof a beam line of the NP-hall will be 750 kW; it is about
100 times greater than the currently slow extraction lineof the north counter hall at KEK 12GeV-PS. Therefore thedevelopment of new technology for handling a highintensity beams is absolutely required. Especially in orderto prevent beam line loss less than a few W /m, thevacuum pipes for a beam transport will become large
aperture such as about a 300mm diameter. According to alarge aperture pipe, a large connection flange is needed.
The existing devices of a flange connection was a
Conflate flange, a V-band coupling with an elastomer
rubber and a metal O-rig, and the pillow seal flange, etc.
That flanges which uses with a bolts-nuts is mostpopular, many industrial standards was employed in theaccelerator facilities. But these flange devices have many_________________________________________*yamanoi@post.kek.jp

bolt parts, to need much time for a fasten work, and it
must fasten by hands.
Although the V-band coupling of these devices has theflange of large size, the fastening compressed ability togenerate by a belt is small, and it does not have for a
metal seal with radiation hard. The remotely fasten deviceof a V-retainer as evaluated a V-band belt was developedin the north counter hall at January 1990 [2,3].
From the PSI (Paul Scherrer Institute, Switzerland), we
had technology supplied and the pillow seal flange
without bolts and nuts was installed a beam line of thenorth counter hall [4]. The pillow seal device is sealed bya metallic baggy therefore this is given a scratch damageon the surface of a metallic baggy. Also as for a sealing
capacity, a few 10-7 Pa.m3/sec are a limit.
The presently a radial compressed sealing was used ahigh viscosity fluid, for example a water connection. The
flange device by using of a radial seal has a need of asocket and a plug flange. Therefore the flange use
scarcely for a vacuumed beam line. However, a radial seal
flange can realize the large flange by small fastens power,
and there is some possibility that a sealing capacity is also
obtained enough.

2. DESIGN CONSIDERATION
2.1 Design Requirements
The beam line components such as magnets, vacuum
pipes and beam monitors are required to work under very
high radiation environments and will have very strong
residual radioactivity. Maintenance of these equipments
must be carried out against very high radiation. Therefore
the most important character is that it must never break.
However, in the case of need, maintenance should be
carried out quickly from distant location. For example,
the residual radiation on a primary beam line will be over
170 Sv/hr surrounding the production target after anormal operation period (a half year) [5]. The connecting
devices itself is more radioactive, to install andevacuation in remoteness and a short time formaintenance work. Therefore a seal material with getting
scratch damage and corroding by an oxidized gas is
expected a disposable materials. The quantity of an air

The 14th Symposium on Accelerator Science and Technology, Tsukuba, Japan, November 2003

leak has an influence in a beam line loss, therefore better
than small leak rate of vacuum connections <1x10-8
Pa.m3/sec of He.

2.2 Radial Seal
The radial seal is compressed a sealing ring for radial
direction of a beam line. The radial seal is one of metal
seal is based on the plastic deformation of a lining ofgreater ductility than the materials surrounding it. The
radial seal is possibility of internal and external
compression. Internal compression expands the innerdiameter of the seal. External compression reduces theouter diameter. The cross section of a radial seal structure
seal is shown in Fig.1.

made of a SUS304 is used for the core material, and askin covers with an aluminium alloy A1050 over an
outside. The compressed force is expected a 60 % of anaxial seal, such as 0.54mm for 4mm thickness. When ataper angle is set to 1/10, it is presumed that thecompression force of an axis direction is required a
21daN/cm for this size.

Figure 2: The cross-sectional forms of each seals

A left figure is the seal flange of a taper plug type withan internal compression and usually moves a taper side.
The right figure is a case of a taper socket flange. And
both types in which an opposite flange of a taper side
carries out movable can be exceptionally considered.
The radial seal has the following excellent characters.
1. Tightening force required the 1/10 of an axial
compression flange.
2. The plug and socket flange have self-guide
function, with large tolerance of a centres of bothaxes.
3. It is easy to install.
4. The seal material is a disposable.
On the other side, the weak points are as follows.
1. The plug and socket flange is necessary.
2. The tightening stroke is long.
3. An air leak may be cause between the different
materials such as a seal and a flange in heat
expansion.
4. The lubrication on taper surface is essential.
The cross-sectional form of the seal material used for
figure 2 is shown. The type-A of figure 2 is usual axial
type seal section form. Pressing carries out a seal fromright and left by the parallel plane. The type-B, C and D
were prepared for radial seals. Each seal is a lack ofdifferent angle and especially the outer cover of type-D iscarrying out overlap structure. The sizes of a seal ringused for the R&D are a 210mm of an inner diameter, anda thickness of 4mm. The size use is actually expected to
be is about 300mm in a diameter of an effective inneraperture. The spring coil which puts in a ring tube was

He LEAK RATE [Pa.m^3/sec]

Figure 1: The cross section of a plug and socket

The relation of the compression force and a sealcapacity performance was checked in figure 3. The seal
performance to expect with 1x10-8 Pa.m3/sec was reachedby compression force smaller in early stage. And themarginal value was observed about 1x10-9 Pa.m3/sec inthis case. However it is the seal capacity performance,
which can also fully use this for our beam line.
1.0E-02
1.0E-04
1.0E-06
1.0E-08
1.0E-10
0

2

4

6

8

10

12

14

COMPRESSED FORCE [daN/cm]

Figure 3: The compression power and a leak rate

3. EXTERNAL COMPRESSION
3.1 Taper socket flange
First radial seal device of a taper socket type wasdeveloped at March 2003. The asymmetry for flanges of
weak point of the radial seal is settled that to insert andthe plug-plug or the socket-socket flange expand between
fixed flanges as pillow seal. Here is a figure that shows infigure 4. The dotted line of right and left in a figure 4
assumes the situation where it was installed into themagnet. The reason for having chosen both taper socket
types is that it is inside a compressed taper that is easy
given a scratch damage. It is easy to install a seal ring andThe 14th Symposium on Accelerator Science and Technology, Tsukuba, Japan, November 2003

is based also on the reason, which can be carried out
outside of a beam line with the extended equipment ofcentre. The picture of the device is shown in figure 5.

The seal capacity of the taper plug type is slightly goodthan the taper socket type. The taper plug type to which aseal ring can extend this outside is considered.
At present, the remote flange device of the taper plug
type is under development, the picture is shown in figure7.
And now its performance is checked.

Figure 4: The concept of external compression

Figure 7: Outside view of the taper plug device(Internal compression)

5. SUMMARY
Figure 5: Outside view of the taper sockets device
The result of the experiment was that the sealing
capacity is 1x10-8 Pa.m3/sec. The seal capacity of themetal seal ring is about 1x10-9 Pa.m3/sec of marginal
performance. One explanation for an insufficient of sealcapacity may be that external compression is not
uniformity without lubrication. Moreover, because of the
trace left behind to the seal ring, the seal line by which aseal ring and a taper socket have touched moved in asnaky circle line.

4. INTERNAL COMPRESSION
Although it thought that there was no difference
performance from the compression method so much at the
beginning of development, by the above result, the sealcapacity performance of an internal compression (a taperplug) and an external compression (a taper socket) was
compared using the same size sealing in figure 6.

The radial seal for a connecting device of highviscosity fluid technology was established to sufficientuse for a future vacuum-connecting flange for handling ahigh intensity beam. The radial seal flange of large
diameter is carried out an airtight by small tighten force.
A metal seal ring of internal compression is carried out ahigh seal capacity with a few 10-10 Pa.m3/sec.

6. ACKNOWLEDGMENT
This work was partly supported by a Grant-in Aid for
Scientific Research (A)(2), No. 15204024 of the Japan
Ministry of Education, Culture, Sports, Science andTechnology (Monbu–kagaku-sho).

REFERENCES
1.

2.

SEAL CAPACITY [Pa.m^3/sec]

1.0E+00

INTENAL COMPRESSION

1.0E-02

EXTERNAL COMPRESSION

3.

1.0E-04

1.0E-06

1.0E-084.
1.0E-10
0

5

10

15

20

25

30

35

40

45

COMPRESSED FORCE [daN/cm]

Figure 6: The seal capacity performance of an internal
taper and an external taper was compared.

5.

The Joint Project Team of JAERI and KEK, “The
Joint Project for High-Intensity Proton Accelerators”,
KEK Report 99-4, July 1999.
Y. Yamanoi, et al., “Development of A highIntensity Beam Handling System at KEK-PS New
Experimental Hall”, The 7th Symposium on
Accelerator Science and Technology, KEK-Preprint89-165, December 1989.
M. Takasaki, et al., “Handling of High Intensity
Proton Beam at 12Gev”, the 2nd International
Symposium on Advanced Nuclear Energy Research
Evolution by Accelerators, KEK-Preprint-89-180,
January 1990.
Y. Yamanoi, H. Ishii, K.H. Tanaka, M. Takasaki, M.
Tsuchiya, “Development of the pillow seal flange fora high intensity proton beam line”, Gijutsukenkyukai-hokoku, p.86-p.88, August 1993.
K.H. Tanaka, “Technical design report for the slowextraction beam facility at the 50-GeV PS in KEKJAERI joint project”, KEK Internal 2002-8, July
2002.