... type), L (winding type), high frequency welding;3, fin tube materials: 1, base tube: carbon steel, stainless steel, copper, copper alloy, titanium and ... type, high frequency welding), copper (winding type).4, finned tube specifications: 1, base tube: OD16, OD19, OD1 ", OD38; 2, fin: OD34, OD44 ...