1. SEALING DEVICES　1. 1 Gaskets

(1) Type
The static seal filling the space between flanges is called a gasket. Gasket is categorized as soft gasket (nonmetallic),semi-metallic gasket and metallic gasket (Table 1.1.1).
Soft gasket is made of non-metallic materials such as rubber, resin, graphite, inorganic fiber and
organic fiber. It is used at low temperature and low pressure 300 ℃・3MPa or less.
Compressed sheet and fluorocarbon resin (PTFE) gasket is typically used. Expanded graphite gas-
ket being used widely in recent years.
Semi-metallic gasket is a combination of metal and non-metallic materials, and is used at mild
temperature and under mild pressure about 500 ℃・10 MPa. Spiral wound gasket and metal-jacke-
ted gasket are typically used.
Metal is processed into a specific shape and size to make a metallic gasket. Generally, used at high
temperature and high pressure about 800 ℃・45 MPa. or less.

(2) Selection and selection guide
(a) Selection standard for a gasket
(i) Selection procedure for a gasket
Procedure to select a suitable gasket is as follows:
① Fluids: Verify the type of fluid in Table 1.1.2.
② Temperature and pressure: Select a compatible gasket for the temperature and pressure range
(Fig. 1.1.1 to 1.1.5) for the fluid type.
Table 1.1.2 Fluid classification

Fluid classification	Typical fluids
water fluids	Water, Seawater, Warm water, Hot water, Steam, Superheated steam, etc.
oil fluids	Crude oil, Volatile oil, Naphtha, Kerosene, Diesel oil, Heavy oil, LPG, Alcohol, Furfural, Ethylene glycol, Ethylene, Propylene, Butane-butene fraction, Butadiene, etc.
solvent,corrosive fluids	General solvent, Aromatic hydrocarbon (B.T.X, etc.), Ketones, Amines, Ethers, Phenol, Acrylonitrile, Liquid ammonia, etc. Acids and alkalis such as mineral acid, Organic acid, Mixed acid, Acidic solution, etc.
gaseous fluid I	Air, Nitrogen gas, Inert gas, etc.
gaseous fluid II	Flammable gas, Combustion enhancing gas, Noncombustible gas and toxic gas, etc. H2, Town gas, LNG, CO, etc.
low temperature fluid.	LPG, liquid ethylene, LNG, Liquid oxygen, Liquid air, Liquid nitrogen and DME, etc.

Table 1.1.1 Type and properties of gasket

*Refer to notes and remarks in Table 1.1.1
Note
  (1) Hardness （JIS A）is less than 75
  (2) Hardness（JIS A）is 75 or more
  (3) Temperature limit varies depending on the materials
  (4) Expanded graphite filler may varnish using the gasket at
    over 400 ℃ depending on shape or construction of flange

Remarks:
  Gasket factor (m) and minimum seating stress (y) are the
  values indicated in JIS B8265 and JIS B2206, except for the
  following:
  (i) Different values depending on the metal materials are indicated in range.
  (ii) ※ is the value set up by VALQUA.

Numbers in the figures indicate VALQUA No.