Improved Seal Paste

1. Introduction
When seal paste is applied to gaskets, the scratches in

3. Characteristics①The product does not contain crystalline silica,

flanges are filled with the paste, improving the sealing

which is carcinogenic, nor organic solvent

properties. Therefore, seal paste has long been used

including highly hazardous dichloromethane andfor gasket connection.

toluene. The product is safe and environment-

Although there are no problems with the conventional

friendly.

seal paste, user demands for safety and theenvironment are getting stronger, so we developed anWinter 2018
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②improved seal paste.

Since the product contains a solvent with a highflash point, it is categorized as a non-hazardous
material（combustible solids under the designated

2. Product summary
The improved seal paste is a light brown paste based

combustibles*）.
③

The new product has similar properties to theon a special, non-drying, oil-based bond formulated

conventional seal paste. When applied to gaskets,with inorganic filler and a small amount of solvent.

it works as a sealing adjunct, protects the flanges

The formulation is an improvement over thefrom rusting, and prevents gaskets from adhering

conventional seal paste, as it contains no carcinogenic

to the flanges.

substances. In addition, it is categorized as a nonhazardous material under the Fire Service Act. Thus,
the product is safer and more environment-friendly.

④

A brush is attached to the cap, making it easy toapply to gaskets and other objects.

Note : C ombustible solids under the designatedcombustibles: Products whose speed ofcombustion expansion is fast in the case of fire,or whose combustion is difficult to suppress.
Petroleum asphalt and some other products fall
into this category. When the amount of such aproduct exceeds a designated amount（ 3,000kg）, it is categorized as a combustible solid
under the designated combustibles; when usedor stored in amounts lower than 3,000 kg, it iscategorized as a non-hazardous material.
Figure 135

Improved seal paste

Product introduction

4. Applicable fluid
Conventional seal paste

The improved seal paste is applicable to water, air,

Improved seal paste

gasoline, kerosene, lubricating oil, natural gas, LPG,
used when hydrocarbons including ethylene, butane,and ethane are handled, and helps prevent deposit
corrosion on the surface of stainless-steel flanges.

Leak rate

cold water, and hydrogen sulfide. The paste can beLower leakage detection limit

5. Service temperature range

Gasket stress

Figure2 Test results of checking the sealing properties at room temperature−50 to 300ºC

Table2

Test conditions for checking compression fracture
Gasket

6. Product form

Gasket dimensions

730 g of paste in a capped metal can with a brush

No.6500
φ100×φ64

t=3mm

Gasket stress

70、100MPa

Amount of paste applied

Approximately 1.75 g on both sides7-2）Test‌
to check resistance to compression fracture

7. Performance dataapplied to gaskets to which either the improved seal

improved seal paste has properties equivalent to thosepaste or the conventional seal paste was applied, toof the conventional seal paste.

evaluate the contact pressure at which compression
fracture occurs.

7-1）‌Test to check sealing properties at room
temperature

No abnormalities occurred at contact pressures of up
to 70 MPa, neither with the improved seal paste norTo evaluate the sealing properties of each paste,with the conventional seal paste. Compression fracture

various low contact pressures were applied to gaskets

occurred at a contact pressure of 100 MPa with bothto which the improved seal paste or the conventional

pastes, verifying that the two pastes have equivalentseal paste was applied. As a result, leakage fromproperties. Figures 3 and 4 show enlarged photos ofgaskets using the improved seal paste stopped at acontact pressure of 7.5 MPa, the same as leakage fromgaskets using the conventional seal paste. This result
demonstrates that the improved seal paste has
properties equivalent to or better than those of theconventional seal paste.
Table1 Test‌
conditions for checking the sealing properties atroom temperature
GasketGasket dimensions

No.GF300
JIS

10K

50A

t=1.5mm

Fluid

Nitrogen gas, 3.5 MPa

Gasket stress5、7.5MPa
Improved seal paste
Conventional seal paste

Type of paste
Amount of paste applied

Approximately 0.7 g on both sides

Winter 2018

Contact pressures of 70 MPa and 100 MPa wereThese performance data demonstrate that theFigure 3 Compression-fracture‌
test of conventional seal paste
Compression fracture was confirmed at 100 MPa.
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Improved Seal Paste

8. Conclusion
Since legal regulations on toxic substances anddangerous substances are becoming stricter due tosocial demands regarding safety and the environment,
customers increasingly need products that meet suchsocial requests. Accordingly, we will continue todevelop safe and environment-friendly products forusers.

Figure 4 Compression-fracture‌
test of improved seal paste
Compression fracture was confirmed at 100 MPa.

gaskets which suffered compression fracture.

Winter 2018
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37

Masato Hamade
Corporate Research andDevelopment Group
Product Development DivisionⅠ