On site hardness testing is carried out by means of a portable hardness-testing unit. (Leeb Model TIME HLN-11A) This unit is capable of converting values such as Brinell, Vickers, Rockwell and Shaw. On site hardness testing is required to compare production welds in the parent metal, Weld Metal and Heat Affected Zone (HAZ) mainly after Post Weld Heat Treatment (PWHT) has been carried out to ensure the hardness values are acceptable within each zone of the weld joint. Usually 3 spots are testing within each zone and an average reading qualified. The advantage of on site hardness testing is you are able to ensure that parameters have been keep for the Welding and Post Weld Heat Treatment during both processes.