diff --git a/src/phasicFlow/structuredData/box/box.cpp b/src/phasicFlow/structuredData/box/box.cpp
index 7f16f754..c374c926 100644
--- a/src/phasicFlow/structuredData/box/box.cpp
+++ b/src/phasicFlow/structuredData/box/box.cpp
@@ -36,7 +36,15 @@ pFlow::box::box
 	(
 		dict.getVal<realx3>("max")
 	)
-{}
+{
+	if( !(min_ < max_))
+	{
+		fatalErrorInFunction<<
+		"the corenter points of box are not set correctly"<<
+		" (min point is greater than max point). In dictionary "<< dict.globalName()<<endl;
+		fatalExit;
+	}
+}
 
 FUNCTION_H
 pFlow::box::box
@@ -58,6 +66,13 @@ bool pFlow::box::read(iIstream & is)
 {
 	if(!is.nextData<realx3>("min", min_)) return false;
 	if(!is.nextData<realx3>("max", max_)) return false;
+	if(!(min_ < max_))
+	{
+		ioErrorInFile(is.name(), is.lineNumber())<<
+		"the corenter points of box are not set correctly"<<
+		" (min point is greater than max point). In dictionary "<<endl;
+		return false;
+	}
 	return true;
 }
 
diff --git a/src/phasicFlow/structuredData/box/box.hpp b/src/phasicFlow/structuredData/box/box.hpp
index 67d0e8dc..13a3fe7b 100644
--- a/src/phasicFlow/structuredData/box/box.hpp
+++ b/src/phasicFlow/structuredData/box/box.hpp
@@ -31,14 +31,14 @@ namespace pFlow
 
 class box
 {
-protected:
+private:
 	
 	// - min point
 	realx3 	min_{0,0,0};
 	
 	// - max point 
 	realx3 	max_{1,1,1};
-
+	
 public:
 
 	// - type info