visa free transit in Shanghai

I have a flight from hong kong to shanghai and then 4 hours later from shanghai to paris. I will not be leaving the airport. Ihad a single entry Chinese visa for travel befote i went to Hong Kong. Am i correct in thinking i dont need that to transit in shanghai airport? Ia there any application to go through for free transit or do you just go through immigration aa normal? Can i get confirmation of this in case my hog kong flight doesnt let me board? I have an irish passport. Thanks