Pilot's nozzle

Referencing to API 537 approve that Pilot's nozzle, ignitor, thermowell, venturi fabricated of stainless steel is better than castable ones. this is for flare system. try to be more scientific in properties of the materials, ambient factors of the flare system that affect the materials plus the condition of temperature, pressure, humidity, thermal shock, at flare system condition and the process going on inside. the type of the pilot is HEI, FFG