Metal Hollow O-ring

Metal Hollow O-rings are made of thin metal pipe processed into circle or other specified shapes,
whose both ends are butt-welded. As they can offer sealing with a relatively low tightening force and also compact gasket joints can be designed,
they are used in various types of equipment for high temperature & high pressure, as well as high vacuum applications.

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Product name
Metal Hollow O-ring, Balanced type

This is the same as No. 3640, except for a small hole created on the inside (for internal pressure) or on the outside (for external pressure) for balancing.

Applicable Fluid
Inappropriate fluid
Used for aerospace semiconductor-related facilities, nuclear power-related facilities, electronic industry, laser equipment, joints, valves, injection molding machines, etc.

■ Coating material service temperature and the tube material

  Materials Service temperature(℃)
Materials of Pipe Stainless steel(SUS304) -250〜540
Stainless steel(SUS316) -250〜820
Stainless steel(SUS321) -250〜870
Incoloy 800 -250〜980
Cover metal Coating material : VALFLON(PTFE) -200〜260
Plated silver -250〜650
Plated nickel -250〜760
Plated copper -250〜400
Plated gold -250〜850

■ Available ranges

Temperature (℃) Pressure (MPa)
Depending on component metallic materials Vacuum - 300 MPa

■ Manufacturing ranges

■ Manufacturing ranges ■

Pipe symbol Pipe dia × Pipe thickness SUS304 SUS316 SUS321 インコロイ800 Minimum radius of curvature for rectangular type (ID) Dimensions can manufactured
(Outer diameter)
J 0.9×0.15       4 8~100
L 0.9×0.25      
G 1.6×0.15       7 11~200
A 1.6×0.25
M 1.6×0.35      
B 1.6×0.5   6
H 2.4×0.15       22 25~350
C 2.4×0.25
N 2.4×0.35       17
D 2.4×0.5 10
E 3.2×0.25   45 40~1500
O 3.2×0.35       38
F 3.2×0.5 20
P 3.2×0.8      
I 4.8×0.5     75 200~2000
K 6.4×0.8     90 400~2500
◎:The material often used ○:Standard Stock Material

Note(1) Use as reference for corner radius values for Rectangular Type seals.

■ Upon placing order


Q. Do you have an O-ring that can be used in 400℃-500℃?

A. The metal hollow o-ring can be used.

Q. I want to control the width of the opening in the flange such as with a sheet gasket. How should I do this?

A. Control with width of the opening in the flange is prone to cause a margin of error and an accurate tightening stress cannot be obtained. It is effective for uneven tightening, so please use it in conjunction with control of tightening torque.

Q. Please tell me about the difference in the gasket dimensions between flanges of the JPI and ASME/ANSI standards.

A. JPI basically quotes from ASME/ANSI, so there are cases in which the dimensions differ slightly due to rounding error during the millimeter conversion of the original number. We understand that, in actual use, the function of the gasket is fulfilled to an equivalent degree by both dimensions.

Q. Why does leakage occur during stop or re-operation even though there are no problems during plant operation?

A. Expansion and contraction of the flange, bolt, pipe and the like will occur due to temperature changes. As a result, a tendency of reduced tightening force in the gasket main unit is often observed when the temperature decreases (including low temperature at the time of initial re-operation), and leakage occurs due to relaxation. We therefore generally recommend a retightening of the gasket before re-operation after the first heat addition.

Q. Is retightening effective when leakage occurs?

A. Yes, it is effective. We ask that retightening during leakage be performed after relieving internal pressure. However, there are also points to keep in mind for each product, such as the possibility of damage as a result of temperature-induced hardening in the case of a compressed non-asbestos fiber sheet.

Q. I am not sure which gasket to select, so could you select it for me?

A. If you contact us together with your operating conditions, we will recommend an appropriate product based on our technician's selection.