A safety is there for a reason.
If you ever see the aftermath of a boiler explosion, you will
As a guy who runs old steam boilers now and then, I feel a need to "pop off"
(pun intended) on this.
I've used steam cleaners on occasion and those that I've used are simply
"open." There is no way they can build up any appreciable pressure. You
light the burner and open the water valve. You get water for a while, then
you get steam. Since the system is "open" there is no opportunity to build
up any appreciable pressure.
On the other hand, the safety on a boiler, from a practical standpoint,
covers for you on two different (related) fronts. First is the situation
where you clumsily get the fire a little too hot and make a little more
steam than is being used. The other is when you make steam expecting it to
be needed and then the hogger (who, embarrassingly, may be yourself) doesn't
take it. But, in these cases, you only have a "little" too much to be
disposed of. If things go horribly wrong, the safety isn't going to take
care of it all and you're apt to send your dumb ass in the general direction
of the moon.
The safety will cover a mistake. Total stupidity is another matter...