VALFLON Sheet Gasket

These are Sheet Gaskets made of VALFLON (PTFE) with excellent properties for chemical resistance and non-stick.
(VALFLON is a registered trademark of NIPPON VALQUA for its fluorocarbon resin products)

no image
VALQUA No.
7020 (food)
Product name
VALFLON Gasket
Features1
In order to overcome the cold flow (creep phenomenon) which is a drawback in PTFE, these gaskets are shaped by means of a special manufacturing process where inorganic filler material is compounded.
Features2
Provided with heat resistance, chemicals resistance, and anti-cold flow property, they are best suited for lines handling various chemicals (high concentrated hot sulfuric acid and hot nitric acid, etc.) .
Features3
Unsuitable for High concentration alkali like Sodium hydroxide, Hydrofluoric acid, Polymerizable monomer
Features4
These comply with the Food Sanitation Law.

Conforms to the Food Sanitation Act and standards for food and additives


Applicable fluids
Water, Sea water, Hot water, Steam,Crude oil, Alcohol, Animal & vegetable oil, Heat transfer oilGeneral solvent, Weak acid, Weak alkali,Air, Nitrogen gas, Inert gas,Exhaust gas,Inflammable gas,Poisonous,Oxygen,Extremely low temperature liquids,
Inappropriate fluid
High concentration alkali like Sodium hydroxide, Hydrofluoric acid, Polymerizable monomer
Application
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 ingredient
PTFE, Silica
Color tone
Beige

■ Available ranges

Temperature(℃) Pressure(MPa)
-200〜200 4.0

Temperature and pressure show individual service limit

■ Pressure

Nominal thickness(mm) Size(mm)
1.0 1000×1000
1.5 1000×1000
2.0 1270×1270
3.0 1270×1270

■ Design criteria

Thickness(mm) Gasket factor”m” Minimum design
seating stress"y"
(N/mm2
Recommended
tightening stress
(MPa)Liquid
Recommended
tightening stress
(MPa)Gus
1.0 3.5 24.5 20.0 24.5
1.5 3.2 22.5 20.0 24.5
2.0 3.0 19.6 20.0 24.5
3.0 2.5 19.6 20.0 24.5

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 m, y values of VALFLON Gaskets are the same as those of fluororesin gaskets specified in JIS B 2206.

■ Characteristic values of VALFLON Gasket

■ Characteristic values of VALFLON Gasket ■

Item 7020 7026 7010-EX 7010 7GP66 Remarks
Thickness(mm) 1.5 3.0 1.5 3.0 1.5 3.0 1.5 3.0 1.5 3.0 -
Tensile strength(MPa) 15.6 15.8 24.2 23.2 26.4 24.2 30.2 27.3 24 18.4 JIS R 3453
Compressibility(34.3MPa) (%) 4 5 4 5 20 12 19 12 69 71
Recovery(34.3MPa) (%) 69 54 67 63 63 48 51 64 15 16
Density(kg/m3 2330 2300 2070 2070 2210 2200 2170 2180 620 670 -
Creep relaxation
(20.6MPa)(%)
100℃×22h 37.2 55 42.8 60.8 63.7 79.6 75.9 88.4 51.9 68.3 JIS R 3453
200℃×22h 66.7 81 79.3 85.5 86 90.8 92.4 97.3 59.3 75.3
Sealability(1) Without paste (Pa・m3/s) 1.7×10-4以下 1.7×10-4以下 1.7×10-4以下 1.7×10-4以下 2.8×10-4 -

Note (1) Sealability Test criteria: JIS 10K50A, Internal pressure 1.0MPa, Tightening stress 25.5MPa, Thickness 1.5mm
Remarks: The above values are measured ones, and not regulatory values.

■ The fluid-wise available ranges

流体別使用可能範囲

■ Stress strain characteristics of VALQUALON

バルカロンの圧縮復元特性(No.7020/7026)

■ Notes to be observed in design and usage

■Notes to be observed in design and usage■
▼Notes to be observed in design

・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.
・Being liable to suffer cold flow, these have to be used in locations permitting tightening control including periodic retightening. Since the gaskets are composed mainly of thermoplastic PTFE, retightening shall be performed not under hot temperature condition, but under cold temperature condition after initial heating. As for No.7010, grooved flanges should be used in principle.
・Determine the construction, material and dimensions so that the flange is not likely to cause rotation.
・Consideration shall be given in design to prevent application of excessive thermal stress or repetitive bending stress on the joints.
・Piping design shall not allow accumulation of drain or scale at the flange sections.
・Consideration shall be given to prevent transmission of vibration to the joints.

▼Notes to be observed before installation
・Check perpendicularity of the flange and the pipe.
・Shaft alignment of the mating flanges shall be ensured.
・Check for any deformation of flanges.
・When changing only gaskets for the existing equipment or at a piping joint, clean the connecting section and check for any damage, and repair, if required.
・Get off the rust at the flange surface, and repair any dents and dings.
・Pay attention not to give damage to gaskets during storage up to installation, or during installation work.
・Dimension of this product may change after fabrication due to the characteristics of the raw material.

▼Notes to be observed before installation
・Install the gaskets in a clean environment so as to prevent entry of foreign matters between the gaskets and the flanges.
・If gasket paste is to be used, apply a minimum amount of "VALFLON Paste" uniformly. Also care shall be exercised after application of paste, to prevent adhesion of dust and the like.
・Flange bolts No.1 to 8 as shown on the figure shall be gradually tightened in this order at a time, and repeat this process in four to five steps, so as to finally ensure uniform tightening.
・When tightening, pay attention to prevent the occurrence of crush. Especially 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.
・At the time of load up or restarting, check for any loose bolts.
・If retightening of gaskets that have once experienced leakage failed in preventing leakage, replace them with new ones.

▼Notes to be observed in storage
・Store these joint sheets in a cool and dark place not subject to direct sunshine, fresh air or ozone.
・Storage selected shall be in a clean environment, free from dust as well as from high temperature & high humidity and corrosive atmosphere.
・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.
・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 product in molten alkali metal, high temperature hydrofluoric acid and chlorine trifluoride due to chemical erosion.

■ FAQ

Q. What are the precautions when coating the gasket paste to 7020 and 7026?

A. The surface is coated when the flange accuracy is low, but you need to be careful about the tightening force because it will become slippery. If you will coat the surface, use the New VALFLON(TM) Paste and coat it as thinly and evenly as possible.

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.

■ VALQUA HAND BOOK TECHNICAL DATA

■ VALQUA HAND BOOK DIMENSIONAL DATA


back