Anatomy of a Catastrophic Boiler Accident (1997)
nationalboard.org
nationalboard.org
The Navy's SUBSAFE program [0] arose directly from the 1963 loss with all hands of the USS Thresher, which is generally thought to have resulted from a cascade of damage ultimately traced back to a shipyard's faulty silver brazing of a salt-water pipe [1].
[0] https://en.wikipedia.org/wiki/USS_Thresher_(SSN-593)#SUBSAFE...
[1] https://en.wikipedia.org/wiki/USS_Thresher_(SSN-593)#Cause
There are a lot of very interesting things to see there, but one thing that stood out is how they took me and a couple of other prospective employees to see the memorial wall to the Thresher in one of their conference rooms. Even fifty years later it felt that the incident was still well known at Portsmouth and influential on their culture.
Later I would work at facilities handling much more dangerous weapons that seemed to lack anywhere near that level of personal connection to safety culture, despite a legacy that had claimed numerous lives and not only among the enemy.
https://www.youtube.com/watch?v=HV5FGTxIU4Q
video is about:
The Navy released the ninth and tenth set of documents from a previously classified investigation into the April 10, 1963 loss of USS Thresher and its crew of 129 sailors off the coast of New England.
https://news.usni.org/2021/07/09/navy-releases-latest-round-...
maybe interesting
In the private sector in the US, there's The Hartford Steam Boiler Inspection and Insurance Company, established in 1866. They were the first company to insure steam boilers, and they still do. They inspect them before insuring them, and re-inspect at random times thereafter.
They've been trying to expand this approach into "cyber insurance", but with limited success. They will insure the cooling and power systems for your data center, though. They know how to inspect those.
From reading the OP it appears the failure was the replacement nuts, not the re-used bolts.
This wasn't a failure of the boiler vessel itself, although the article says that the stop valve was defined as "a boiler-boundary".
BTW 600 psi and 850 F is a lot of heat and energy. UPDATE a post below talks about 1200 psi 975 degree superheated steam.
For example, the TÜV[0] in Germany was founded in 1866 after "the explosion of the boiler at the Mannheim Aktienbrauerei in January 1865, the idea was pursued there to subject boilers to regular inspections on a voluntary basis, as was already the case in Great Britain".
[0]: https://en.wikipedia.org/wiki/Technischer_%C3%9Cberwachungsv...
As a trainee I was helping a crew supervise a power plant in charge of providing superheated steam to a large nuclear facility.
There was a bronze plaque on the ground in one of the technical room where some guys had been cooked alive.
Superheated steam and boilers scare the hell out of me.
Functioning modern society/things in general just working (for those of us living in developed countries) is incredibly fragile and regulations are often still taken completely for granted.
The accident is an example of the rare cases where the tolerance for error is tiny to prevent catastrophic consequences. Usually systems are designed with multiple lines of defense but this is not possible with a steam valve. The process to ensure that the correct fastenings were used was not in place. Ideally in these cases engineers should use poka yoke where the device can't be assembled incorrectly e.g. using an unusual thread size or marking all low strength fasteners in an obvious way to indicate low strength
https://medium.com/@bhavyamangla/error-proofing-poka-yoke-fo...
but the jigsaw pieces with the words "Poka" "Yoke" can be connected in seven incorrect ways :-)
In an online legal forum, a lawyer said (paraphrasing), "I keep trying to make my master services agreements more and more idiot-proof, but they keep coming up with better and better idiots."
Programming today is a race between software engineers striving to build bigger and better idiot-proof programs, and the Universe trying to produce bigger and better idiots. So far, the Universe is winning.
According to the reports it happened because a technician installed the innertial measurement unit upside down. It was supposedly designed to be impossible to do that, but the technician found a clever way to bend the PCB :)
I’m on the commercial side, so maybe industrial is different?
While much less physically exhausting, he doesn't much like his new job supervising, which entails alot of walking around and exclaiming, "WTF!?"
https://www.littlepeng.com/single-post/2017/06/29/major-valv...
I hear software engineers frequently talk about things being "dangerous", but IMHO most of the time it's incomparable to the dangers in working with heavy machinery.
[1] https://en.wikipedia.org/wiki/British_Airways_Flight_5390
and it wasn't the only mishap, though the deadliest.
This makes it sound like the mechanic was out of his depth, if he didn't know about the importance of nut material in a high temperature application.
The subsequent failures in inspection are not excused, of course.
However nuts and bolts suffering differential expansion so badly to cause a total failure I have never heard of. I would attribute at least half the blame to the original designer for not having enough dimensionality and/or strength margin on the threads.
600psi steam is only at a little over 225 degrees Celsius, which really isn't much thermal expansion for metals.
There is so much that can go wrong in engineering systems. Unintentional mistakes could lead to dire consequences. Safety and quality assurance programs may seem like time consuming inconveniences, but have a very important role.
Steam systems still have plenty of uses, but there is no longer any need for storage of large quantities of high pressure steam in a boiler.
Steam should be treated like electricity - generate and use it at exactly the same rate. That way, you need no storage, and if a pipe bursts there won't be an explosion.
Was there ever a time where the environment was not one of cost cutting and increased profit margins?
1) Safety systems work so well that people get complacent. "Approval of the fasteners is required, so I'm not going to get out a flashlight and mirror and double check."
2) At one point, many failure modes were totally unknown. Someone discovers them for the first time. You can have a comprehensive safety program that's well funded and always performed correctly, but if there is a failure mode that nobody knows about, it's as likely to happen to you as it is to someone else.
And hey, at least people give safety lip service. Nobody ever posts signs that says "cost cutting is our #1 priority", they always say that safety is their #1 priority. Their heart's in the right place at the very least ;)