XPS foamed board, has a perfect closed-pore alveolate structure. Lts density ,water absonrption, coefficient of heat conducing and the coefficient of steam pervasion are all lower than those of other board heat preservasion materials. They have the characteristics of strong intensity,light material,airtight,anticorrosion,aging resistance,low cost,etc. It has been widely used in the fields of heat preservation and heat insulation in the construction industry ,frost resistance of the highway, railway, aquare and household fitment.It is the generally acknioledged and best heat preservation material.