Properly Set Safety Valve

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Fred M. Freschette
Courtesy of Fred M. Freschette, R. D. 4, Red Deer, Alberta, CANADA.

R. R. 4, Red Deer, Alberta, CANADA.

I wrote an article in your magazine about boiling a boiler dry
with a ‘properly set safety valve’ without the boiler
exploding. It has been brought to my attention by a good friend
that my statement regarding properly set safety valve could be
misunderstood and I agree, so I will try to clear this matter

I could have said, leave the safety valve off. However, whether
you have one on or off, I hope no one will ruin a good boiler to
find out. To write about boiling boilers dry just makes good
reading and brings up a little controversy, but nothing is really
gained unless someone relates their experiences so that others can
read and maybe absorb some good from them.

Here are a few boiler experiences I have had:

1. Case boiler from 110 H. P. Installed in Welshe’s Western
wear in Red Deer. Boiler used for heating. Relief valve set at 20
lbs. Controls failed to operate. Boiler was boiled completely dry
and fire continued in firebox until the outer shell was dull red,
so firebox would be much hotter. No explosion with relief valve at
20 lbs. Repair all flues loose and stay bolts neededends turned
down. Flues rerolled, otherwise boiler put back in service and
still okay.

2. Butt Strap Rumely 20 H. P. boiler in Schodopoles shop at
Eckville. Relief valve 20 lbs.

Controls failed and boiler boiled dry plus it was oil fired and
this extremely hot fire continued until it was discovered in the
morningouter firebox shell was red from the heat.

Repairs: all flues rerolled and all stay bolts ends turned down
plus some seams recaulked; this boiler was so hot that the engine
mount rivets were also leaking. After repairs boiler was put in
service and is still going strong.

3. Red Deer Water plant. 2 pass horizontal boiler that controls
failed on relief valve set at 20 lbs.this boiler was so hot that
the doors to the boiler room had to be left open for some time
before the fire could be turned off. Repair: roll and reroll flues,
welded construction so no stay bolts loose-boiler still in

I could go on and on but we are dealing with 20 lb. boiler
pressure so if there was a proper setting I would say 20 lbs. is
about it as the above seems to bear this out.

Let’s try the higher pressure:

4. Traction Engine 65 H. P. Case 1915 Butt Strap boiler used for
heating water in town of Manning, Alta.

Relief valve set 150 lbs. Inlet and outlet water shut off,
apparently. Boiler boiled down quite a ways below crown sheet
before the crown sheet let go. It dropped off 8 stay bolts and it
sure did clean the grates and blew the firebox door off. I was
asked by the old fellow if I would repair it for him. I was up
north on holidays and I told him I would repair it for free as most
individuals cannot afford to hire a boiler-maker. I rolled the
flues twice and caulked the inner firebox seams, and beveled the
stay bolt ends and also the crown sheet holes then I heated and
carefully jacked the crown sheet up into place, then I welded the
stay bolts into place and if I do say so, it was a nice job. I left
this engine with 100 lbs. cold water test and it could, with some
work on the stay bolts be brought up to test but I quit because the
help I was to get never arrived and after 2 days of crawling in and
out of the firebox I said to heck with it as it seemed I was the
only one interested in fixing it.

The oil industry claimed many of our traction engine boilers for
use on drilling rigs. I believe some of the engineers who run them
had a grudge against these boilers by the way they abused them.

I have built this miniature boiler for a 3′ 32 Reeves Cross
Compound that John Kvill of New Norway, Alberta, CANADA, is

I have seen boiler under steam, pumped full of drilling mud
because the mud pit overflowed into the water pit that the boiler
was drawing water from. Can you imagine a boiler filled with
drilling mud while under steam? The water legs were all bagged and
the mud turns into cement, so these boilers all made a one-way trip
to the scrap dealers. Also have seen crown sheets dropped from 35
lbs. up. This was done by injecting or pumping water on dry crown
sheets of course no safety valve can handle the explosion of water
into steam at this time.

Also have seen flues so badly limed up that all the flues were
froze together in one big ball of lime inside the boiler.

Hand hole plate left leaking until it grooved and channeled so
bad that the area had to be built up and ground down, flues in
front sheet left leaking until the flue sheet was channeled and had
to be repaired.

Have seen the cab blown off a locomotive with no one hurt and
also seen a collision between two locomotives where the engineer
and fireman were both scalded to death.

I would say Barring Material Defects, that 99% of the boiler
explosions in Canada and the U. S. A. were and are caused by Human
Error, about 95% from someone injecting water on a dry crown sheet,
and the other 4% caused by someone setting up the pressure on an
old worn-out boiler.

I do hope this clears up the safety valve setting and also
throws a little light on the subject. I also wish there were others
who would write of their experiences, as I think boiler repairs and
boiler failures should be kept in this magazine all the
timeconstant reminder to all as to what can happen through
carelessness and stupidity.

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