I had no issue doing 24 hr TWOV with this itinerary, IKA-URC-PEK-ICN, with Spain passport: Before buying the ticket directly from the China Southern ticket office in Tehran they assured me that I would be able to do the Urumqi + Beijing transit as long as it was under 24 hours total. I also called the CZ ticket counter at IKA and spoke with the station manager who assured me that if I purchased this ticket I would have no problem checking in for this itinerary without a visa. So I purchased the ticket the next day at the CZ Tehran city ticket office the following day (paid in cash in IRR so the one-way ticket in J only cost about 200 EUR ). After purchasing the ticket I called the IKA CZ ticket counter one more time to be 100% sure I would have no issues checking in on day of departure and once again the station manager assured me that ticket qualified for TWOV. At check in I had no issues at all with regards to TWOV just as promised (however they would only check me in as far as PEK. they said I had to get my PEK-ICN boarding pass at PEK). Also no issues at URC immigration, was issued the 24 hr stamp just like at any other china airport in the past. I did not have to collect the luggage there at URC myself but it did go through customs there and was transferred directly to the URC-PEK flight. Then at PEK I had to pick up my luggage and go outside and check in for the PEK-ICN leg.***SIDE NOTE - My particular routing from IKA-ICN had layovers of 1:45 in URC and 4:30 in PEK. However there were other options available connecting via PVG, CAN or DLC instead of PEK which would have had longer than 2 hour transits in URC, but the CZ station manager confirmed to me that I could have also booked one of those routings and they still would have had no issues checking me in using TWOV. I also asked the immigration officer at URC (who spoke english very well) about this alleged 2 hour max URC rule and she also told me that those itineraries would have been fine, that the only thing that matters is 24 hours total time in China.