I'm trying to do a same day turn from Dtw to Pek. Do I require a visa if im not leaving the airport? I have a us passport.

Are you stopping in Japan in either direction, but not both? (If the answer is negative, then you need a visa.)

On the out bound it's Dtw sea nrt pek Dtw.

Then you should be fine. Safe travels.

OP is entitled to 24 or 72 hour TWOV and can leave the airport.

Correct. They don't care whether or not you leave the airport, but they are strict about the 3rd country requirement.

My schedule is:
SEA-PVG-PEK arriving at 11:30 PM
Leaving 7:30 AM next morning PEK-NRT-SEA
Does this qualify for TWOV?

You're good to go.

You are NOT good to go with that itinerary, because you must clear immigration in your first port of entry in China, PVG. Transit without visa means you must depart from the same inbound airport to a third country.

Can I go straight to transfer without visa if I'm not leaving the airport?

No, it does not. You have 24 hours from arrival to get out of China from any exit point. For the 72 hour exception, you must come and go from the same city.

skchin: You will be IN China in your case; whether or not you leave the airport(s) is up to you, but I wouldn't be caught dead overnighting @ PEK2.

I'm not planning on leaving. I will arrive at 1130 pm and go straight to transfer desk to catch the 730 am flight next mornng. Why is overnighting in pek2 bad idea?

Moondog, your information is not correct.

"Visitors are not allowed to leave the transit city to other cities during the 72 hours. They can only depart from the same airport where they get their permit issued."

This is from the Chinese Embassy regarding transit without visa. The TWOV is valid for specific cities, and those cities only.

The OP doesn't need 72 hours. His plan is completely (as in 100%) viable since his total stay in China <24 hours. We've had many, many threads on this.

ETA: It's also worth noting that TWOV applies at every airport in China that has international flights, but only a handful of cities have the 72 hour exception.

I was not referring to the timing of OP's stay. If he arrives from the US to PVG, he will apply for his TWOV in Shanghai. The rules do NOT permit him to depart next day PEK NRT, as per the below from the Chinese Embassy FAQ regarding TWOV.

7、 In case a foreign national has entered China with the 72-hour transit visa exemption issued by the Capital Airport of Beijing, can he or she apply to leave China from an airport in Shanghai?
Answer: A foreign national with the 72-hour transit visa exemption is not allowed to leave the city where the stopover is permitted. Therefore, a foreign national obtaining the 72-hour transit visa exemption at the Capital Airport of Beijing shall leave China from the same airport in Beijing within the permitted time of stay and may not leave China from an airport in Shanghai.

I am trying to point out to OP, that he runs a real risk of a problem even if he is in China only for 24 hours, because the arriving city and departing city are not the same