help with British engineering qualifications

[jep24601]

We got the P.E. system because there was no system previously and disasters abounded.

We got the PE system because local Authorities would not hire competent people to check designs (costs more - raises taxes) and so the PE system was introduced whereby only a "competent" person can be "be responsible for" the design.

There is no substitute for properly checking a design by a competent third party as the disaster at the Hyatt Regency proved.

[ckelloug]

My recollection of the Hyatt Regency Disaster was that a junior engineer, a P.E. no less, signed of on an engineering change order to a threaded support rod increasing the stress on the joint between it and a beam. If I remember right, the safety factor of the original design was around 2 and the poorly thought out change reduced the margin to around .8 or .9. Wikipedia's numbers and story vary from what I remember and the version of the story there appears to have been mangled by the popular press and possibly politicized. Looking into the issue more deeply, the following powerpoint charts from Drexel University provide an excellent explanation of what happened including pictures the failed parts: See http://www.mse.drexel.edu/Programs/s...y-collapse.ppt

The Hyatt Regency Disaster was a striking example of how the P.E. system we have in the states can fail spectacularly when someone does not think through every aspect of a system. Of course you want more people than one checking something. In principle, a P.E. is supposed to have a good enough understanding of the engineering principles and the consequences of failure to make sure that whatever it was was checked well enough and by enough people that it will not fail in practice.

Any engineering design can fail if a mistake is made. I seem to remember that there were an extraordinary number of cast iron bridge collapses in the early days of British railroad bridge construction. The British never developed the U.S. P.E. system for railroad bridges either and yet they overcame the design issues with cast iron bridges. Additionally, analyzing some of the bridge failures planted the seeds for the science of fracture mechanics and pointed the way to steel rather than iron railroad bridges.

For me the bottom line is that wherever and whatever is being done, competent people should be reviewing the designs and checking them, certifications or not. Like in science, more review usually means more thorough checking.

I'm not here trying to defend the American, Canadian, or British systems, I'm only posting to share the history of the system as I was taught it and to reiterate the point that there are areas beyond the basic mechanical domain where productivity and ultimately public life safety issues demand that there are people who actually understand every nuance of the theory behind what is being done.

Quiz question: Reading the Drexel powerpoint, does everyone understand how the design change doubled the load on the nut holding the walkway to the support? I find it a bit subtle but very interesting.

[loose nut]

In another case someone says they're a Mechanical Engineering Apprentice - and that involves milling, grinding, turning etc. Are your Mechanical Engineers what we'd call machinists? Cities and Guilds - is the a trade licensing or educational entity?

In Britain, what we would call a machinist, on this side of the pond, is or was called an engineer, not to be confused with an engineer that designs things or drives a train. Different terminology for the same thing.

[loose nut]

A neighbour of mine in Manchester used to do that for British Engine.
There seems to be a perception in the US and Canada that because you have to have a PE with a stamp to stamp documents that there is somehow a greater safety in the US/Canadian procedures. Nothing could be farther from from the truth. There is such a thing as "plan stamping" in the US. It is far safer to have bodies like Zuric Insurance or British Engine behind a boiler certification than some individuals PE stamp.

I don't know how it is done in the US but in Canada, even when a design is stamped, at least with pressure vessel, piping etc., it is still subject to gov. inspection and approval.

[jep24601]

In Britain, what we would call a machinist, on this side of the pond, is or was called an engineer, not to be confused with an engineer that designs things or drives a train. Different terminology for the same thing.

??????? My mother was a machinist in Britain she sewed overcoats on a sewing machine.

[loose nut]

I would have liked to be an engineer but I'm glad I didn't go that way (other then the obvious lack of brain power), I wouldn't have liked the cut in pay.