Grade 14 Ball Bearing 5 Knuckle Hinge Square or Radius options.( Max Load 160kg). The most popular type of door hinge on the market today. They have a CE mark and are Certifire tested, BS EN 1935 rated. Suitable for industrial, commercial and domestic use. Ball bearing hinges have always been very popular for their smooth operation, durability, long lasting design and ability to carry heavier loads than washered hinges. For standard internal residential doors a pair of hinges is adequate;Â however fitting 3 hinges per door has its advantages. It will look aesthetically pleasing and from a practical viewpoint it helps spread the load evenly and will help to overcome twisting or warping. This can sometimes happen to doors over a period of time where heat and moisture are a factor.