When you look at all the safety mechanisms in place even since the 50's such as interlocking lid pins operated by pressure, blow out vents or valves, contorting, V shaped gaskets that will buckle and vent with over pressure, it's hard to believe if just the jiggle valve stem or pressure regulation valve gets blocked. 15 psi isn't that much pressure if you think about it either, probably the same in a soft drink can shaken and less then half of what your tires take. Then there's the one that I love to hear about boiling oil for those brave enough to think they're going to play col. Sanders. True, some very cheap gaskets in cheap imports may have problems with oil over 400 degrees, but the silicone used in most any decent quality PC won't. If it does, it's just not going to hold pressure and leak, not explode. Then we have this pesky problem of physics relating temperature and pressure. So you do the col. sanders and get the oil to 375-400 degrees and start dropping in your chicken after it browns a little bit. Then you put on the cover and lock it into place, Miss V*ck*e and other litigious averse companies who have a vested interest in promoting a new style, modern (say expensive) PC like to advance the exploding boiling oil myth. Total crock of crap and maybe a good episode for mythbusters. The minute you cap the lid with the oil and chicken something happens thanks to the laws of physics. The temperture drops very rapidly under pressure to around 250 degrees and further cooled by the steam generated from chicken juices in minutes. After 10-12 minutes of cap time, the exit oil temp is less then 300 degrees and main reason you want to get it out as fast as you can to keep the chicken from absorbing oil at that low temp. Otherwise, the risks are no different then using an immersion fryer that potentially can be much more dangerous with oil near 400 degrees and easily boil over if you're not careful. We can't ignore stupidity though. There are some people that can't seem to follow instructions and properly seat and bayonette the lids. My mom was like that. Instructions and common sense were for idiots and fools. Forget the fact that most all lids have poistive locking systems under pressure to insure this doesn't happen, you can improperly have bayonette a lit snug, but not positively engage the locking which is glaringly obvious. The lid can pop off, but will below 15 PSI and make a mess of an overflow on the stove, not propel the lid and do structural damage. Even if every safety was blocked and you were using a so-called pre-war cast pot that may not have had any safety besides the blocked stem and some even didn't have a positive locking besides the handles joined. That's either going to take some strengh to twist apart and the possibility at those pressures for the older cast metal to rupture is insane....well smart enough if you want to scare someone into dumping grandma's pot for a brand-new $300 scandinavian pot that you'll still be scared to use. I still have my grandmother's pre-war 4 quart PC's that thanks to geting a new gasket off the net and new blow-off valve for the heck of it for $8, it's in use again since the 70's. I have 4 euro clamp type cookers from 4 to 15Q (canner), an electric 6Q presto that I now favor for pressure frying small batches instead of the super heavy clamp units, and one 4/8Q new fangled Fagor set that's been reduced to being used as large pots and deep frypan because the so called safety handles without a jiggler. Nice idea, but when the internals get gummed up or need parts, Fagor is nice enough to just want to sell you the entire handle assembly at near 2/3rds the cost of what you paid for the set with shipping and handling last I tried. Fine stainless pots though with great glass lids for general cooking.
Get a grip people. If something actually goes wrong, it's not the pot, it's the user and they shouldn't be allowed in a kitchen with other potential dangerous utensils or appliances. Like anyting else, they need occasional maintenance too. New gaskets and running a piece of wire or toothpick through the stem for a safety precaution. You don't pull out a PC that was a wedding gift 30 years ago and use it without checking it out with some water first any more then firing up a stove stored in your basement for 30 years. You don't fill the cooker up past 2/3 volume. All common sense.
And yes, frying chicken in a pc with 1/3 oil volume is safe...very safe despite litigation averse companies and pajama wearing blog pundits having you believe that you're essentially creating a hot oil bomb. You can also vent a regular PC quikly with a large serving spoon by tipping the jiggler to one side instead of placing it under water. My preferred method. I'm going on 45 years soon using these things with no incidents and my grandmother probably did the same using 4 old quart units with bakelite handles, one that I mentioned that I still use. Every kitchen down here uses one and probably learned as I did in my teens how to use them.