Important notice on selection

① Fluid, temperature, pressure
Selecta gasket with corrosion resistance depending on the type of fluid to be sealed.
Some gaskets with corrosion resistance may have different criteria for temperature and pressure.
Verify application for the fluid type in Fig. 1.1.1 to Fig. 1.1.6.
The selection guide of gasket is established in consideration of permeability,toxicity,
inflammability, explosivbility and corrosion resistance of the fluids.
Special attention is needed for the folowing fluids:

a.Oxygen and combustion enhancing gas:Gasket made of flammable materials should be avoided. Spiral wound gasket with PTFE filler, PTFE gasket, copper metal jacket gasket and metallic flat gasket are often used.
b.Polymerizable monomer:Compressed sheets and PTFE gasket may not be used for polymerizable monomers such as styrene monomer or vinyl chloride monomer.Select a spiral wound gasket with an inner and an outer ring, a metal gasket or a special fluorocarbon resin for monomer envelop gasket.
c.Fluids containing slurrysoft gasket may cause a leakage or be damaged due to erosion. Select a spiral wound gasket with an inner and an outer ring, or a metallic gasket.
d.Heat transfer fluid:Compressed sheet causes a leakage due to degradation of the rubber binder. Spiral wound gasket with non-asbestos filler may cause a leakage during long time use. Expanded graphite sheet gasket or spiral wound gasket with expanded graphite filler are suitable.
e.Radioactive fluids:PTFE cannot be used against radiation. Expanded graphite has 1 x 106 Gy of radiation resistanc.

② Application and equipment
T ypes of gasket are limited on some level depending on the application or equipment they are
applied to.It is necessary to select gasket materials with high reliability that are to be used at
the key point of the manufacturing process, or in areas that cause significant effects on the
surroundings when there is a leakage.。


〔Piping〕
JIS or JPI standard flanges are used, and has RF, FF or RTJ face.
Compressed fiber sheet, PTFE envelope gasket, spiral wound gasket and ring joint gasket are selected for piping.
PTFE gasket with special filler (VALQUALON gasket) or expanded graphite sheet gasket are used
as well.PTFE gasket with special filler is significantly improved with creep property which is a weakness of PTFE.
Used when more stable sealing is required than PTFE envelope gasket or pipe flanges,
under pressure fluctuation or heat fluctuation and in a narrow working area.
Expanded graphite sheet gasket has a small stress relaxation ratio which provides long term stable
sealing, and has high chemical-resistance and heat and cold-resistance. Used as a seal for low
temperature fluids such as LNG and liquid ethylene, for high heat and pressure fluctuation or with
permeable liquid such as thermal oil.

〔Heat exchanger〕
Flanges with Male-Female(MF) face or Tongue and Groove(TG) with 500 to
1500 mm diameter are mostly used.Some shell and tube heat exchangers have partitions.
Compressed fiber sheet, metal-jacketed gasket and spiral wound gasket are mainly used.
Metal-jacketed gasket is used the most, but spiral wound gasket is suitable when sealing stability is
required due to high heat and pressure fluctuation.


〔Valve〕
Basically, the same gasket material as piping is selected.
There are many choices of flange such as FF,RF,MF,TG and RJ, and the shape of gasket can be oval as well as round.
Serrated gasket, metallic flat gasket or metallic corrugated gasket are used other than gasket that is
often used for piping. Pressure seal ring may be used for high pressure.


〔Tower/tank or reactor〕
Basically, the same gasket material as piping is selected. Metallic flat
gasket, pressure seal gasket or double-cone gasket may be used for high pressure.



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