Boiler Explosions?

RayWohlfarth

Steamhead posted about a boiler explosion and it baffles me how this can happen anymore. I was teaching a class on boilers and one of the engineers told me he would never recommend a boiler for his customer because they are dangerous. I explained how you were more likely to be exposed to carbon monoxide poisoning from your oven than a boiler exploding. I asked him if he has a stove at home. Most commercial boilers have redundant controls and are very safe. If the owner does simple maintenance on the boiler, the odds of a boiler explosion are very low. Insurance companies are also scared of any company working on boilers. It frustrates me. Thanks for allowing me to vent.

Jamie Hall

Ray's quite right, of course. Assuming that a) your boiler has the basic safety controls (high pressure cutout and low water cutout) and b) the party on site maintaining it has a minimum of clues as to how to take care of it -- if only to call a professional when the safeties shut it off -- boilers are among the safest things around.

However... as we all know, people -- including some folks who really should know better -- will bypass safeties. They will put valves (or caps!) on dripping PRVs on water heaters, too. They used to put pennies in fuse boxes. They... sigh... as @Steamhead might say, you can't fix stupid.

Zman

I am curious what type of heat that engineer recommends?
I imagine he just does roof top units.
I have never estimated it but the loss on those things must be huge.
With just a thin sheet of metal between the combustion side and the air, the risk of CO must be high as well.

bob_46

When I went to Weil McLain school back in the 60's they told us cast iron boilers were safer than steel. There had been an explosion at a telephone company facility, I believe it was in New Jersey and the boiler took off and went through the cafeteria at lunch time, killed a lot of people. The steel boiler ripped and that formed a kind of rocket nozzle. Cast iron won't do that, a large piece will blow out and relieve the pressure so the boiler won't take off. That telephone company wouldn't allow steel boilers in their facilities after that.

RayWohlfarth

Jamie how true
ZMan he just cuts and pastes specs for packaged rooftop units
Bob I heard that also. Although I would never want to be any room where the boiler explodes.

Solid_Fuel_Man

Anyone who has been to a third world country like Bangladesh, knows how easily something like this can happen. We've all seen safety bypasses here on our own soil, by maint people who may or may not know better. Overseas it is the wild west. When I was in the Middle East, some of the things that I saw were scarier than the guys we see on the news.

Taylor

Henry

We had a client that decided to do his own annual steam boiler maintenance. He did none. 2 years later his boiler failed. He wanted a deal from Smith. We discovered that he did no blowdowns and that the pump control/low water float was jammed. All the sections failed at once when they started it up for winter. The fire department showed up due to all the steam vapor coming out of the combustion air duct ounto the street.

Steamhead

I just looked at a Weil-Mclain 4-80 steamer that dry-fired. The installer (OBVIOUSLY not us) used a single float-type LWCO and no one blew it down. The crack in the front section looked just like the one in Henry's photo. Funny thing, we were there several years ago, found the same LWCO issue and cleaned everything out. Told you so.......

The 80 series has two tappings for LWCO probes. Our proposed replacement will have two probe-type LWCOs in the mandated CSD-1 configuration.

Steamhead

Found the quote I was looking for. From John Mills, 1890:

"There are two great and unmitigated evils, that cling like a pestilence around the neck of individuals and society- intemperance and boiler explosions- both reckless and needless squanderers of human life and happiness- the first largely responsible for the second".

Substitute "stupidity" for "intemperance" and the same quote is still true today.

You can see his book here:

https://books.google.com/books?id=uGNGAAAAMAAJ&pg=PA214&lpg=PA214&dq=intemperance+and+boiler+explosions&source=bl&ots=oNUO4Zmf0C&sig=z_1TkVp_H05uH8yX6oc68lKGawg&hl=en&sa=X&ved=0ahUKEwiSu9PBzIrPAhWBQiYKHQyPAYQQ6AEIHjAA#v=onepage&q=intemperance and boiler explosions&f=false

delta T

Years ago (before I was born) my father got a call to be an expert witness for a case where a 850,000 Btu boiler exploded and took out a whole wing of a nursing home. Fortunately and miraculously no one was inside and so there were no injuries at all. The entire 2000 sq ft wing was trashed though....

My dad went out to look at the boiler and see if there was anything he could figure out about why the boiler exploded, and right at the epicenter of the destruction lying on the ground was half of the relief valve that still had a shiny brass plug in it.

Maintenance guy said that someone had reported water coming under the door to the mechanical room on Friday afternoon, he investigated, found the relief valve was running a small trickle, and plugged it for the weekend so that he could replace it on Monday . Impossible to tell exactly why the boiler ran away as it was all a twisted wreck, but plugging the relief valve is almost certainly why they had an explosion instead of a flood.

One wonders how much money is saved by hiring incompetent maintenance staff who will naturally accept lower pay....

Steamhead

It probably didn't run away. A trickling safety valve tells me it's probably a hot-water boiler. If so, the expansion tank was probably waterlogged. If so, when the boiler fired, there was nothing to relieve the expansion pressure, so BOOM!

All together now...................

delta T

Yes it was hot water, only reason I think it may have run away was the scope of the explosion, just about leveled the part of the building it was in. Would that not indicate the water being super heated to some degree and flashing to steam once the boiler burst and the pressure dropped? How energetic would the boom be if there was no conversion to steam? I am sure you are right and the exp tank was waterlogged, just thought that for that kind of explosion you would need steam in the mix too.

Not to say that the boiler wasn't operating off its high safety limit at 220 either, who knows.......

you can't fix intemperance.......no wait....the other one

RayWohlfarth

Solidfuelman, thanks I have never been inside a boiler room outside this country. It just upsets me that people get hurt or killed and it could have been avoided.

RayWohlfarth

Henry, That is so scary. It could have been so much worse
Steamhead, Delta T, and Hatteras, Thanks so much I thought I was the only one with untrained customers. I had a customer where the fire department sprayed the boiler with cold water and it cracked every section of the boiler. hey were so lucky

Steve Ebels_3

Had one this winter that could have been really bad.
The lady of the house came home from work and noticed a "hot" smell in the house. It was also cold in the house so she went down to look at the boiler and noticed it was firing and really stinking bad.
Thank the Good Lord and her guardian angels she called her husband before turning on the manual feed valve.

He advised her to shut off the power and let it cool down. Judging from the burned off paint and the melted gauge (yes melted, I still have it in my office) the sides of the iron sections must have been red under the jacket.

Her hubby came home 2 hours later and opened the feed valve. The block was still hot enough to crack instantly, ruining the boiler, if it wasn't already at that point.

Now here's the good part...the boiler had supposedly been serviced by a local company who had been doing it for years before this couple bought the house...only 2 months prior.

This is what we found.
*Both M/M LWCO's bypassed. One float type and one electronic.
*The pressure switch was held closed with a needle nose pliers jammed into it. Looked like it had been there for years.
* The relief valve was completely stuck. Could not lever it open with a screwdriver.

The only operating control still functioning on the whole system was the old T87 on the wall upstairs! It fired as long as the thermostat was closed.
There was a hole in the bottom of the block you could stick your fist in. The piece of iron that fit the hole laid right under the boiler.

Amazing.

Steamhead

So how much did they win in court?

Solid_Fuel_Man

My father in law buys repossessed buildings and "rehabs" them into apartments. 4 or 5 years ago, small ranch he bought in the middle of winter. They dumped a few 5 gal cans of oil in the tank and filled the boiler....surprisingly it held water (water not steam) and let it go. Well the aquastat never opened when the boiler reached temperature. Only one zone circulator worked anyway. Well it kept running lucky the relief valve opened and the city water kept running. Filled the whole place with so much steam some drywall fell off the ceiling. Until the oil ran out.

Taylor

Steamhead

And he didn't call you to check it out before starting it?

BobC

@Steve Ebels i had a similar experience back in the late 70's. One Sunday morning in August I noticed something smelled hot in the back hall. i went downstairs and found the landlords Delco DB5 steam boiler with a 12" spot glowing red and smoking. The boiler had a coil in it for hot water.

I killed the power and shut off the oil supply and then opened up the basement door to air the place out. The LL asked why I didn't just add some water .

They replaced the boiler about a week later.

Bob

Solid_Fuel_Man

@Steamhead nope, but I did see and repair the aftermath. New control, circs, oil line, filter, smoke pipe, etc. Clean&tune.

It's better if I don't work for family, at least not their apartments. I don't like doing minimal work. If it's worth doing, it's worth doing right the first time.

Taylor