FRA requires a Factor of Safety of 4.
ASME now is 3.5
What is the lowest Factor of Safety below which a boiler should not be operated?

There is no option to vote for what would seem to be the correct answer, which is 4 if certified by the FRA; 3.5 if certified under the ASME codes.

Matt,

Your question is miss leading in a small way....

I think that for "power boilers" (i.e. those found in public commercial use, such as schools, hospitals and industry use) we in the US should be allowed to compete with the rest of the world. If we do that, we need a Margin of Safety (we are reminded that the proper term is not "safety factor", but Margin of Safety) of 2-2.5. Right now, we in the US applying the code must meet the 3.5 standard. This puts us at a disadvantage when competing internationally for work.

Besides; as you well know, the BULK of our pressure vessel accidents are HUMAN error not mechanical failure. I am not down playing the mechanical factor, I am simply saying, rarely do we have major failures at Margins above 2. I hope you understand what I am saying.

Now, if you are asking about Steam Locomotive Power Boilers, I have a totally different opinion. I believe that a Margin of Safety of 4 is the only way to go. I believe that all possible and or potential governing authorities should establish a standard for specific items. Matt, you know as well as I, that we have locomotives that move in and out of jurisdictions. As such, we end up with great problems as these boilers move from State to Fed jurisdiction. A common rating would curtail this problem in the future and establish an even playing field.

As a business man, I believe that we need a two sided approach. A.) we can compete on a safe level in terms of the power boiler industry on an international level and B.) that we have a standard accepted by all governing (potential or real) agencies, accepting the fact that industry power boilers are NOT Steam Locomotive Boilers.

I voted above for a Margin of Safety of 4....I believe your question related to our industry.

Respectfully,

John E. Rimmasch
Wasatch Railroad Contractors

wrrc.us

The National Board used to publish incident reports that tracked the number of boiler injuries and deaths by cause. The two biggest reason were always "operator error" and "poor maintenance". Both come under the "human factor", and by far the "human factor" is biggest reason for boiler incidents in the US.

With that being said it's also important to understand our history and the 10,000+ deaths per year from boiler accidents before the formation of the ASME codes. These codes put into place the "factor of safety" along with construction and repair standards and the number of boiler accidents plummeted to a couple of hundred. Pardon me for not having the exact numbers.

Our present construction standards are the reason there are hardly any deaths due to poor design/construction. Any thoughts of lowering standards should be made with only the most serious thought.

Considering industrial power boilers - I'm far more concerned about the potential for critical failures in digital automated systems that control the boilers (at least in theory) than in problems caused by human error, provided that the humans involved are competent and motivated. IF a factor of safety of 2-2.5 has been found to be as effective in other nations, we ought to look at it and all other ancillary factors necessary to make it as reliable here.

Locomotive boilers - a very different animal, both due to age, fluctutations in steaming rates, and no proven operating system beyond humans. We have no national standards for our humans to be tested to conform to before letting them fire and maintain our locomotives. I think we can improve our humans in railroading, and use more humans and trust computers less in industry. Any acceptable factor of design safety is much less material that good operating and maintenance management.

That said, I'm pretty comfortable with John's ideas.

dave