Transiting through Pek is one of my least favourite experiences and all too regular! They have 2 transit desk stations conveniently located outside the normal traffic zones so you often walk past them oblivious to their existence and from whichever direction you have disembarked its usually the furthest one that you need to go to. Firstly try to get UA to give you the TG boarding pass at your departure, never know your luck. If not the transit desks on both sides at PEK are prior to walking through the health checkpoints (they have body temperature scanners then you get to immigration). If it is not the first transfer desk you need to continue walking past immigration and the opposite health check to the second transfer desk area.

Once you have boarding pass you need to go to the far left area of immigration to go through and get stamped at the transit section of immigration, proceed downstairs and queue to get stamped again at the security checkpoint, then proceed to pass thru security.