Conform to BS4658 part 1 and BS EN 50086-2-1            
Screwed thread both ends with one end fitted with a coupler            
Pre-Galvanized ( Dull Grey with Visible weld line - Unclassified)            
Post hot dipped galvanized steel ( Dull Grey - Class 4 external and internal )            
Black Enamelled ( Black and Shiny - Class 2 external and internal)