I am travelling to Sanfrancisco by China southern airlines I have Indian pass port and USA tourist v

Layover is at Guangzhou for 4 hr and technical stoppage at wuhan for 1 hr 55 min do I need transit Visa or it is covered under 24 hr transit free on return journey I will come by China southern flight layover for 2 hrs at Guangzhou then fly to New Delhi .is it under 24 hr transi free .I will not leave guongzhou or wuhan airport.
B p Bhatnagar India