An old anecdote. I was co-leading a group backpack trip once, and I brought along my hot MSR white gas stove to do half of the cooking. My co-leader brought along his Svea 123, although he was not very experienced with it. When it came time to do some cooking, he dripped a few drops of fuel over the burner for priming. He lit it, it flickered for a few seconds, and then it went out. So, he dribbled more fuel over it, pumped the little mini-pump, and lit it again. Again, the fire danced around for a short period and then went out without getting any real pressurization going in the tank. For the third go, he dribbled several spoons of fuel over it, furiously pumped the mini-pump, and lit it. This time it caught. The priming fire was more of a blaze, and the pressure built up rapidly. The burner was going great guns, and then it happened. The pressure safety relief valve opened in the filler cap. All of a sudden, a diagonal fire jet was shooting out of the filler cap, and the thing looked like it was about ready for a shuttle launch. My co-leader didn't know what to do. He had no fire blanket to throw over it, and he had no water standing by. It seemed ready to explode. I just kicked it over in the sand with my boot, and then kicked more sand over it, so it was out in an instant. Needless to say, the safety valve was melted and permanently failed, so that Svea was retired to the junk heap.
The stovies on this forum have probably seen this before with inexperienced Svea users.