There seems to be a confusion of water temperature and pressure on this forum so I will offer this link:
http://www.engineeringtoolbox.com/saturated-steam-properties-d_273.html
In a simplest form, if you give me the pressure of the container, I can give you the temperature of the water. If you give me the temperature, I can give you the pressure in the container.
Let use look at a pressure cooker that is operating at 15 psi and venting. The table shows that the pressure would be about 250 degrees F for the water..
If you would tell me the water was 250 degrees F, I would reply the temperature is about 15 psi
Pressure cooking takes two forms.
If the product is in the water, the product feels the full temperature of the water. Non vented
In canning, the temperature needs to be a saturated temperature above the level of the jars to transfer heat into the jar. Vented