Boiler explosion last April in St Louis, anyone know the exact cause?

GBart

http://abcnews.go.com/GMA/video/killed-boiler-explosion-caught-camera-46562554

GBart

I found it, interesting read, it wasn't a boiler explosion it was the condensate tank.

http://www.csb.gov/loy-lange-box-company-pressure-vessel-explosion-/

GBart

from CSB report:
On the day of the incident, there was a steam explosion inside
the Loy Lange building. A steel vessel weighing about two
thousand pounds--referred to as a Semi Closed Receiver or
SCR–launched through the air. The damage caused by the force
of the steam explosion left one Loy Lange Box Company
worker fatally injured and another in critical condition.

The SCR pulled loose from all the piping and floor attachments,
and rocketed up through the Loy Lange building. It went
through the roof, traveling at almost 120 mph. It rose to about
425 feet above street level and traveled laterally across
approximately 520 feet, and it remained airborne for over 10
seconds.

The energy released was equivalent to about 350 pounds of TNT.

In 2012, the SCR was repaired when a leak was discovered in
the bottom of the tank. It is important to emphasize that at that
time the entire 30" diameter elliptical bottom portion of the tank
was not replaced. Instead, a 24" center section was removed and
replaced with a custom-formed 24" diameter piece, called a tank
circle.
The remaining 6 inch ring of the original part of the tank—left
behind during the repair on the SCR—connected the new tank
circle and the original SCR shell.

An area of continuing interest surrounds a proposal received by
Loy Lange twenty five days after the repair was completed from
the same contractor responsible for the leak repair work. The
proposal suggested a replacement of the entire bottom of the
SCR to provide additional thickness in order to protect against against corrosion. This replacement ultimately did not occur, but we plan to conduct a more thorough examination of the details of that proposal.

On Friday, March 31, 2017, three days prior to the incident, the
employees again noticed a leak from the bottom of the SCR.
A cell phone was used to photograph that leak. The photo
showed leaks coming from at least two distinct sections of the
remaining 6 inch ring. The steam generation system was shut
down after the photograph was taken, and Loy-Lange contacted
a repair service provider. Plans were made for the repair
technician to arrive in the afternoon on the next business day,
Monday, April 3.

The explosion occurred in the morning of April 3.

Steamhead

Sounds like they cheaped out, and people died as a result. Criminal negligence IMHO.

Solid_Fuel_Man

At what pressure was this SCR running? Superheated water anyone? Scary stuff!

JUGHNE

Being a separate vessel, wouldn't this be required to have a pressure relief valve installed?

GBart

Good question, I found another CSB report, as far as I can tell the investigation is on going and not considered closed. This has a more detailed scenario and equipment layout.

http://www.dli.mn.gov/ccld/PDF/boiler_incident_pv.pdf

GBart

So to summarize, the receiver was holding about 510 gallons of condensed water at 300F and 100PSI, which we know from the Watts movie is close to critical, the tank was on a stand vertically like a rocket there is a schematic in the above report, as the bottom blew out and the condensate flashed off as it hit atmospheric pressure just as a water heater would.

Why they would even consider firing this thing up when it was apparently leaking and rotted means they must not have had a good HVAC education.

GBart

This is going to be a legal nightmare because the city of St Louis has an ordinance requiring them to inspect all SCR's and related equipment which they never did, the city also requires a permit pulled for the repairs of the SCR which was never done, I think in the end there may be too many players who screwed up for charges to be filed, it will just go to Civil court, like the CO poisoning in Vermont years ago at a college, everyone from the landlord to the HVAC co to the installer to the city screwed up.

ScottSecor

Wow, makes me think a little harder about some of the jobs we've done in the past and perhaps we should be a little more cautious on future jobs.

GBart

Well the contractor that did the repair must have stated it was temp and 25 days later submitted a new proposal to do more thorough work adding 50% to the original thickness, it was never approved, they do have an issue with not pulling a permit for the repairs. It was an emergency repair and most places will give you 48hrs to pull after the fact....oops

ScottSecor

Being a person that tries to picture things in my mind... I am struggling to imagine that vessel going that far and that high, after ripping away from the piping and blowing through the roof(s). Pretty damn scary.

GBart

It was almost the equivalent of a small car, CSB estimated the blast to have equaled @ 300lbs of dynamite, not sticks, pounds.

Shalom

At 190 grams per stick, that equals about 716 sticks of dynamite plus one M-80, if I didn't screw up the math. Ouch.

Steamhead

I think it was John Mills who said something like the two greatest evils in this world were intemperance and boiler explosions, with the latter often caused by the former. Not sure if alcoholism was involved in this one, but stupidity certainly was.

You can't fix stupid. And sometimes, people die because you can't fix stupid. This was criminally stupid.

GBart

It became a very interesting case to follow, we're in Hydronics and Steam now and I usually show the Dana explosion and the how/why as it's all on video in the boiler room, happened on this and wow, it was great to find a thorough investigation with diagrams and causes.

Of course I'd prefer that no one got hurt or killed. This is why cities like St Louis have ordinances that companies have to hire boiler operators that have been trained to operate this equipment safely. They always want a "maintenance guy" who is good with sheet rock and light bulbs and they unfortunately get what they pay for.