Founded in 1899, Nippon Kaiji Kyokai, also known as ClassNK and NK, is a ship classification society and a nonprofit foundation. It also conducts inspections and approvals of companies that provide testing and measurement services for the survey and registration of ships and machinery. The society inspects the quality system of the companies and education, training and qualification of technical staff and other personnel. It conducts in-water surveys, plate thickness measurements and radio communication, firefighting equipment and life-saving appliances maintenance inspections. The society also tests the performance of voyage data recorders. Additionally, Nippon Kaiji Kyokai performs tightness testing of hatches using ultrasonic equipment.