We use extruded pipes and steel pipes to make compound pipes through special processing. PTFE compound pipes and fitting with steel linings work properly in the conditions with pressure -70kpa~+1.6mpa, medium working temperature -100oC~+25oC, they are anti-corrosive with almost all chemical media, including nitricacid and sulphuric acid, besides, they may work properly in the temperature between 230oC and 253oC for a long period while other pipes could not meet this condition.