No, a 15A breaker will not trip at 16 amps, at least not for a long time. I can understand why a 15 amp receptacle shouldnt be used on a 20 amp (12AWG) service but a 20 amp receptacle should be able to handle the load safely. But a 15A receptacle CAN be used on a 20A circuit, IF there is more than one.

One may also ask, how many 15 amp receptacles can be on a 20 amp circuit? Table 210.21(B)(3) also shows that a 15 amp receptacle can be installed on a 20 amp circuit that serves 2 or more receptacles. Commentary following 210.21(B)(2) in the handbook clearly states that 15 amp receptacles are permitted on a 20 amp circuit.

Also to know, can I replace a 15 amp outlet with a 20 amp outlet?

Electrical plugs designated as 20-amp will not fit into 15-amp outlets. A 15-amp circuit is usually served by 14-gauge wire and is protected by a 15-amp circuit breaker or fuse. A 20-amp circuit, protected by a 20-amp breaker or fuse, must be served by 12-gauge or 10-gauge wire.

Can I install a 15 amp GFCI on a 20 amp breaker?

Yes, you can legally and practically use a 15 amp GFCI receptacle on a 20 amp circuit (fed from a 20 circuit breaker or 20 amp fuse) - as long as: There are other receptacles on the circuit. OR. the GFCI receptacle is a duplex receptacle.