Many users require that manufacturers confirm the declared characteristics of their valves, especially boundary values: for example, at a lower temperature, with an increased differential pressure. Sometimes it may also concern cryogenic temperatures. For such tests, special equipment is required, as well as special procedures for their conduct which is available at our testing laboratory.
Cryogenic tests are usually carried out at the temperature range from minus 46 ° C to minus 269 ° C, most often at -196 ° C, at liquid nitrogen temperature. The usual practice is to immerse the valve in liquid nitrogen to the level of the gland packing (if the valve is gland). The packing must not be in liquid nitrogen, otherwise it will freeze, which can lead to rod jamming and then the valve will jam. Since the polymer seals work bad at cryogenic temperatures, the connection of the reinforcement must be "hard", that is, threaded, flanged or butt-welded with protective caps.
Cryogenic tests are very expensive and dangerous, they can be performed only by experienced, specially trained personnel. The methods are given in several national standards, and also developed by end users.