Socket welding joints of instrumentation pipes have the risk of fatigue cracking failure in nuclear power plants during long service period. The quality of these joints is related to the safe operation of nuclear power plants. This paper presented the basic requirements of design of socket welding joints of instrumentation pipes from the aspects of suitable application

axial clearance before welding

welding process during welding

leg sizes and non-destructive tests after welding

etc. At the same time

the corresponding welding technology measures were put forward based on these requirements

and adopting these measures would ensure that socket welding joints of instrumentation pipes would be in long-term reliable service. It can provide recommendable technical guideline for normalized designing and manufacturing of socket welding joints of instrumentation pipes.