High Performance Sheet Gasket

Made of ceramic fiber (super heat resisting inorganic fiber) and excellent in flexibility and high temperature heat resistance, these are used as various types of sealing materials, as well as heat insulating material, shielding material and protective material. Since a small amount of organic fiber is included in the manufacturing process, some amount of smoke is generated at the initial stage of heating, while No.105SN cloth and No.112SN ribbon (liver) are smoking prevention treated. As core material of cloth and ribbon yarn, stainless wire is normally used, but others include glass fiber.

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Product name
This is a high-pergormance non-asbestos sheet gasket that can be used for the widest variety of fluids, as different applications are not required depending on acid or alkali fluids.
This is a sheet gasket that enables integration of gaskets on chemical lines. Please contact us if you are using multiple sheet gaskets made by other companies.
Effective for promoting gasket integration at a plant where both alkali and acid lines exist.
This is a product that possesses high-temperature reliability equal to that of other high-performance sheet gaskets (GF300, for example), thereby possessing both chemical resistance and high-temperature reliability.

Applicable fluid
Water, sea water, hot water, steam,Crude oil, alcohol, animal and vegetable oils, thermal oil,General solvents, weak acid, weak alkali,Strong alkali, strong acid,Air, nitrogen, inert gas,Exhaust gas,Flammable gas,Oxygen,Cryogenic fluid,
Inappropriate fluid
Polymerizable monomer, Poisonous
Cover flanges, nozzles and other joints for pipe flanges, valve bonnets, towers and tanks, ovens, pressure vessels, and heat exchangers in factories, electric power plants, oil refineries, steel plants, and ships.
Main component
PTFE, Silicon carbide
Color / print

■ Available ranges

Temperature (℃) Pressure (MPa)
-200〜300 3.5

Remarks: Temperature and pressure classifications show individual service limits.

■ Dimensions

Thickness(mm) Size(mm)
1.0 1270×1270
1.5 1500×1500
2.0 1500×1500
3.0 1500×1500

■ Design criteria

As for the m, y values of High Performance Sheet, the values for Compressed Fiber Sheets defined in the Appendix 3 to JIS B 8265 can be applied.

Thickness (mm) Gasket factor "m" Minimum design
seating stress "y"
tightening stress
tightening stress
(MPa) Gas
1.0 3.50 44.8 25.5 35.0
1.5 2.75 25.5 25.5 35.0
3.0 2.00 11.0 25.5 35.0

The recommended tightening stress are the pressures required under normal conditions, and correspond to the projected area of the gasket, where fluid pressure is not taken into consideration.

■ The fluid-wise available ranges


■ Stress strain characteristics of High Performance Sheet Gasket

(Dimension of test piece: JIS 10K 25A, t = 1.5 mm)


■ Comparison of high temperature hardening properties


■ Comparison of physical properties

■ Comparison of physical properties ■

Item High Performance Sheet Gasket Compressed Fiber Sheet
No.UF300 No.GF300 No.SF300 No.MF300 No.6500 No.6502 No.6503
Thickness (mm) 1.5 3.0 1.5 3.0 1.5 3.0 1.5 3.0 1.5 3.0 1.5 3.0 1.5 3.0
Physical Properties
Tensile strength
(across grain)   
(MPa) 12.0 14.6 12.4 10.9 16 15.8 12 14.1 17 15.3 13.1 12.5 19.2 18.1
(%) 4 4 5 4 5 6 5 4 10 10 9 10 9 6
Recovery(34.3MPa)   (%) 49.0 46 53 54 42 50 32 36 57 55 67 64 60 61
Flexibility with grain in multiple to thickness    (kg/m3)  <2 <2 <2 <2 <2 <2 <2 <2 9 9 11 12 10 10
Density             2576.0 2557 2315 2262 2319 2280 2910 2839 1810 1813 1761 1759 1803 1857
Oil resistance 〈IRM903 OIL 150℃×5h〉
Tensile strength loss (%) 0.6 0.2 1.0 7.6 3.8 5.1 1.5 5.9 16.7 6.3 9.2 9.6 13.0 0.0
Thickness increase (%) 0.0 0.0 0.2 0.1 0.0 0.0 0.2 0.2 2.2 1.2 1.3 1.0 2.1 0.6
Weight increase (%) 0.4 0.2 0.5 0.6 0.5 0.7 1.1 1.4 3.9 3.2 4.4 3.0 4.2 1.7
Fuel oil resistance 〈JIS fuel oil B RT × 5h〉
Thickness increase  (%) 0.0 0.3 0.4 0.3 0.4 0.1 0.2 0.5 5.6 2.8 4.3 2.6 5.4 2.3
Weight increase (%) 1.0 1.2 0.9 1.2 0.9 1.3 0.9 1.8 5.6 4.0 6.7 6.0 7.0 3.2
Creep relaxation〈 JIS R 3453 Tightening stress 20.6MPa 〉
100℃×22h 20.3 44.5 16.2 37.0 16.1 42.7 16.9 30.2 27.5 47.0 23.5 37.8 27.3 45.0
200℃×22h 44.7 71.9 35.3 65.8 40.5 68.8 35.8 55.0 52.0 78.8 41.1 65.5 43.6 60.5
Sealability〈JIS 10K50A, Internal pressure 1.0MPa, Tightening stress 25.5MPa, Thickness 1.5mm〉
Without paste (Pa・m3/s) 1.7×10-4 or below 1.7×10-4 or below 1.7×10-4 or below 1.7×10-4 or below 1.4×10-3 1.9×10-4 1.2×10-3
(atm・㏄/min. ) 0.1 or below 0.1 or below 0.1 or below 0.1 or below 0.83 0.11 0.74
With paste (Pa・m3/s) - - - - 1.7×10-4 or below 1.7×10-4 or below 1.7×10-4 or below
(atm・㏄/min. ) - - - - 0.1or below 0.1or below 0.1or below

Note(1) Flexibility is in accordance with JIS R 3453 6.2.5. Refer to “Comparison of high temperature hardening properties”.
Remark All the above physical properties are measurement examples, and not regulatory values.

■ Notes to be observed in design and usage

The following descriptions summarizes precautions for design, srorage, and installation, in order to properly use Sheet Gasket.

▼ Notes to be observed in design
1.Determine the number and size of bolts and gasket dimensions to provide gaskets with sufficient tightening stress, and also check the flange construction and bolt arrangement to ensure uniform distribution of the tightening stress.
2.Surface finish of the flange shall be about 6.3 Ra (reference: 25 S). Excessive smooth finish may cause slippage on the gasket, leading to crush.
3.Determine the construction, material and dimensions so as to prevent warpage or bowing of the flange at the time of application of internal pressure.
4.Consideration shall be given in design to prevent application of excessive thermal stress or repetitive bending stress on the joints.
5.Piping design shall not allow accumulation of drain or scale at the flange sections.
6.Consideration shall be given to prevent transmission of vibration to the joints.

▼ Notes to be observed before installation
1.Ensure perpendicularity of the flange and the pipe.
2.Ensure the shaft alignment of the mating flanges.
3.Check for any deformation of flanges.
4.Check for any deformation of flanges.
5.When changing only gaskets for the existing equipment or at a piping joint, clean the junctions and check for any damage, and repair if required.
6.Pay attention not to give damage to the gaskets during storage up to installation, or during installation work.

▼ Notes to be observed before installation
1.When installing gas seals, refer to the following "Counter measures against permeation leakage".
2.Install the gaskets in a clean environment so as to prevent entry of foreign substances between the gaskets and the flanges.
3.Flange bolts shall be gradually tightened each time, and repeat this process 4 to 5 times, so as to finally ensure uniform tightening.
4.When tightening, pay attention to prevent the occurrence of crush.
5.In particular, when using gaskets of 150 Lb, 1B or smaller, or those of smaller gasket width, care shall be given as gasket stress is likely to be excessive.
6.At the time of load up or restarting, check for any loose bolts.
7.If retightening of gaskets that have already once experienced leakage fails in preventing leakage, replace them with new ones.
8.Please note that joint sheet may harden over 100℃. Please refer to precaution of available range per fluid and adequate tightening shall be performed initially to avoid retightening after use at high temperature. If necessary, retightening should be performed within 24 hours after heating operation starts and material hardening is not significant yet.

▼ Notes to be observed in storage
1.Store these joint sheets in a cool and dark place not subject to direct sunshine, fresh air or ozone.
2.Storage selected shall be in a clean environment, free from dust as well as from high temperature & high humidity and corrosive atmosphere.
3.If hanged on nails or the like, gaskets may suffer breakage or permanent deformation, so that, as far as practicable, they should be put in a can or wrapped in a polyethylene bag and stored in a paper box.
4. Large sized gaskets shall be put between larger plates without rolling and placed horizontal for storage.

▼ Precautions for safe use for PTFE
Please do not use this products in molten alkali metal, high temperature hydrofluoric acid and chlorine trifluoride due to chemical erosion.

■ Countermeasures against permeation leakage

Since permeation leakage occurs in High Performance Sheet Gasket, the following points shall be observed for gas seals.

1.Apply gasket paste on the cut surface of the gasket inner diameter side. Application of gasket paste on the contact surface between the gasket and the flange is likely to cause crush, so that attention is required in tightening, and also the amount of gasket paste shall be minimized.
2.Maintain the tightening stress to be around 35 MPa. Also use ring gaskets instead of full-face gaskets, so as to ensure proper tightening stress.
3.Use gaskets with a minimum thickness as far as possible (1.5 mm or less).
4.When using gasket paste, please use "NEW VALFLON Paste". No.6 and No.6M for BLACKHYPER are not recommended.


Q. Can inflammable gas be used with GF300?

A. Yes, it can be used. It can be used as long as permeation leakage is prevented by using New VALFLON (TM) Paste.

Q. Is it better to coat a gasket paste on high performance non-asbestos sheet gasket?

A. We recommend coating a gasket paste on the surface of the gasket that comes in contact with the flange and the cut surface of the gasket inside diameter side for gas

Q. May hot bolting be performed on the high performance non-asbestos sheet gasket?

A. Yes, it may be performed. Performing hot bolting has an effect of maintaining the tightening force. However, a reduction of rigidity occurs at high temperatures because PTFE of the constituent materials has thermoplasticity. We therefore recommend to perform hot bolting by control of tightening force while paying attention not to cause damage by excessive tightening.

Q. Why are the GF300 Series as well as 7020 and 7026 (fluorocarbon resin gasket) described to be unsuitable for polymerizable monomers?

A. There are cases in which the polymerizable monomer causes expansion by permeating into the gasket and polymerizing inside it, which results in the gasket to be damaged. We recommend the use of a spiral wound gasket with inner & outer rings or a metallic gasket, which hardly allow polymerizable monomers to permeate, or difficult to damage even if they permeate and polymerize.

Q. Can the high performance non-asbestos sheet gasket be also used on large diameter flanges that exceed the width and length?

A. Yes, it can also be used on large diameter flanges because it can be bonded.

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.