There are very few standards for valves in cryogenic service, which are not written by the end user who will use combinations of/or refer to others already in existence used by the large oil companies.
Installation of cryogenic valves with extensions is either governed by the customer standard/specification i.e. Shell MESC or an International standard such as BS6364, previously Shell had their own independent specification like that of Mobil or TOHO but more recently shell have adopted the majority of the principles in BS6364.
Most of these dictate the valve's build, Assy and test criteria, the emphasis on Testing methods and leak rates stated. Installation may also be defined, BS6364 dictates that the valve stem must not be installed vertical to 45 deg max. this is primarily to stop the packing freezing as liquid runs up the tube the greater the angle from the vertical position. Failure due to external leakage through the stuffing box is almost guaranteed if the valve is installed horizontally.
One common mistake I must point out at this stage when using BS6364 is the extension lengths, Section two, Para 4.5 states that an extension of 250mm should be used for everything not in a cold box, however don't get caught out, the majority of clients actually use 'Table 1' for the extensions length. Table 1 is actually only meant for 'Cold box applications' and only makes a cursory dimensional reference to 'non-cold box applications' on the drg.
