Plate

Abstract

The present invention relates to a plate of a plate heat exchanger, said plate comprising a material which constitutes a part of said plate with a surface made of this material positioned to be in direct contact with a chloride-containing cooling liquid, such as sea water, in which the material is a duplex stainless steel alloy containing in weight-%: C max 0.06%, Si max 1.5%, Mn 0-3.0%, Cr 23.0-32.0%, Ni 4.9-10.0%, Mo 3.0-8.0%, N 0.15-0.5%, B 0.-0.010%, S max 0.030%, Co 0-3.5%, W 0-3.0%, Cu 0-2.0%, Ru 0-0.3%, Al 0-0.2%, Ca 0-0.010% balance Fe and normal occurring impurities, wherein the ferrite content is 35-70 volume-%.

1 . Plate of a plate heat exchanger, said plate comprising a material which constitutes a part of said plate with a surface made of this material positioned to be in direct contact with a chloride-containing cooling liquid, such as sea water, wherein said plate material is a duplex stainless steel alloy containing in weight-%: 
     
       
         
               
               
               
               
               
             
                   
                   
               
                   
                 C 
                 max 
                 0.06% 
                   
               
                   
                 Si 
                 max 
                 1.5% 
               
                   
                 Mn 
                   
                 0-3.0% 
               
                   
                 Cr 
                   
                 23.0-32.0% 
               
                   
                 Ni 
                   
                 4.9-10.0% 
               
                   
                 Mo 
                   
                 3.0-8.0% 
               
                   
                 N 
                   
                 0.15-0.5% 
               
                   
                 B 
                   
                 0[[.]]-0.010% 
               
                   
                 S 
                 max 
                 0.030% 
               
                   
                 Co 
                   
                 0-3.5% 
               
                   
                 W 
                   
                 0-3.0% 
               
                   
                 Cu 
                   
                 0-2.0% 
               
                   
                 Ru 
                   
                 0-0.3% 
               
                   
                 Al 
                   
                 0-0.2% 
               
                   
                 Ca 
                   
                 0-0.010% 
               
                   
                   
               
           
              
             
             
              
              
              
              
              
              
              
              
              
              
              
              
              
              
              
              
             
          
         
       
       balance Fe and normal occurring impurities, 
       wherein the ferrite content is 35-70 volume-%, and that the average Eq1-value of the two phases of the alloy exceeds 40.5, whereby Eq1=% Cr+3.3% Mo, wherein % is weight-%. 
     
   
   
       2 . A plate according to  claim 1 , wherein said average Eq1-value of the two phases of the alloy is higher than 41. 
   
   
       3 . A plate according to  claim 1 , wherein the Eq1-value for both the ferrite and the austenite phase is higher than 35. 
   
   
       4 . A plate according to  claim 1 , wherein the content of Mo is 4.5-6.5 weight-%. 
   
   
       5 . A plate according to  claim 4 , wherein the content of Mo is 4.5-5.5 weight-%. 
   
   
       6 . A plate according to  claim 1 , wherein the content of Cr is 23.0-30.0 weight-%. 
   
   
       7 . A plate according to any of the preceding  claim 1 , wherein the average PRE-value of the two phases of the alloy is higher than 46, whereby PRE=% Cr+3.3% Mo 1-16% N, wherein % is weight-%. 
   
   
       8 . A plate according to  claim 1 , wherein the content of Al is 0-0.1 weight-%. 
   
   
       9 . Plate heat exchanger adapted to utilise a chloride-containing liquid, such as sea water, as cooling medium, wherein it is made of plates according to  claim 1 . 
   
   
       10 . Plate heat exchanger according to  claim 9 , wherein said plates are joined to each other in a stack for forming channels between adjacent plates and that said channels formed in every second gap between adjacent plates are configured to have a chloride-containing cooling liquid flowing therein and said channels formed in every second gap between adjacent plates are configured to have a medium to be cooled flowing therein. 
   
   
       11 . Use of a plate heat exchanger according to  claim 9  for cooling a medium to be cooled by a chloride-containing cooling liquid, such as sea water. 
   
   
       12 . Use according to  claim 11 , in which the temperature of said cooling liquid is allowed to reach a temperature of at least 50° C. 
   
   
       13 . Use according to  claim 12 , wherein said cooling liquid is allowed to reach a temperature of at least 60° C. 
   
   
       14 . A plate according to  claim 2 , wherein said average Eq1-value of the two phases of the alloy is higher than 42. 
   
   
       15 . A plate according to  claim 3 , wherein the Eq1-value for both the ferrite and the austenite phase is higher than 36. 
   
   
       16 . A plate according to  claim 7 , wherein the average PRE-value of the two phases of the alloy is higher than 47.