hydrogen solution and diffusion in "A small welding job"

Hi all "Index" note - a sub-conversation started about hydrogen / weld hydrogen and its investigation in the thread which is "A small welding job"

Reply to
Richard Smith
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And I've been following that conversation - even though about 85% of it is over my head . While most of it is gibberish to me , I have learned from your posts ...

Reply to
Snag

I am happy about that. Conversation flows and as you trust in the people you infer things which are important about the topic. I did my best to convey the story in

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"Memoir of my Doctoral research endeavour"

If you think our talk is bad enough, don't try to read my thesis :-)

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"Hydrogen distribution and redistribution in the weld zone of constructional steels"

With hydrogen, I would like to prove it, but people in Europe are far too concerned about "Is it the lowest hydrogen possible?". I understand that in North America you tack-weld with 6010's? A distinct craziness is the insistence 7018's should go in a rod-oven. If you could have used a 6013, then you can use a 7018 no precautions. Yes a dried 7018 does burn nicer, with a clean transparent arc, as I have known. But no metallurgical necessity for modern Western European steels, which are very "clean" (well-refined) and low-carbon. Knowing the (Euler-Bernoulli) beam equations, I got some offcut Rectangular Hollow Section and took it to the hydraulic press, where I found an "S355" steel (355MPa specification minimum yield) (my-mpa-to-ksi 355) ;; 51.46994842033917 ;; = 50ksi steel. yielded at 360MPa. They control the composition so accurately they "just" make the yield stress, to give a steel which is lovely to punch, saw, drill, etc. So you could weld it with cellulosics on a cold day no precautions.

One weekend I was paid quite well and given an assistant to come in and repair the handrails around the perimeter of a construction barge (flat-topped - being used to store drilled pile tube) after a collision which has "wiped off" all the handrails and stanchions. I took cellulosics - 6010's - with me and went around the scaffold-tube railings full-penetration butt welding them together in-one, no prep. Yes I then did a quick "wash" with a 6013 give a smooth surface. My assistant had never seen anything like it. He felt he had a very rewarding weekend. His Dad was very pleased and was very solicitious when I wanted to learn seafaring navigation (the Dad was a skilled experienced skipper). All this is because of my Doctoral research leading into good mentoring from North America.

Best wishes, Rich Smith

Reply to
Richard Smith

In the past your humble responses and respect for the feedback from those of us who are clearly hacks has made me (if perhaps nobody else) believe you are "just" an experienced line welder. Somebody who may have had a trade school education or may not, but has become an expert welder through years of experience as a production welder. I mean this sincerely. I hope you blew coffee out your nose when you laughed at some of the things I had to say.

In your various comments (and questions)and their accuracy within my limited scope of experience as a self taught hack I had come to believe that you were quite expert in some aspects of welding, but did not perhaps have a full practical grasp of some of the limitations some of us face, and while maybe knowledgeable in most aspects of welding perhaps not so much in areas where you had not expressed a great deal of experience.

I now see that perhaps your expertise is as much academic as practical. I humbly recognize I under estimated you.

Reply to
Bob La Londe

I lack "streetwiseness" as a welder. I lack the background in the myriad of common jobs a welder-fabricator would know. I have to rely on others a lot to show me the way. Things are good if I have earned enough to get that to happen. Where there are things I am good at and favours go both ways.

The areas I do "have an advantage" is where the application has a clear technical structure easily understood with a scientific background and responds to very systematic working eg.

  • spray-transfer GMAW - steel and aluminum
  • cellulosic 6010 SMAW (rare in the UK though) With these processes, a scientific visualisation of how they work guides you. I only had to be shown these once to "grasp what's going on". So these are the things add to the "earned" bank on a job.
Reply to
Richard Smith

I lack "streetwiseness" as a welder. I lack the background in the myriad of common jobs a welder-fabricator would know....

------------------- "Streetwiseness" can backfire. I read of a plane that crashed because an assembler "knew" that the engineer had made a mistake in how a bolt was to be installed and took it upon himself to do it "correctly".

Reply to
Jim Wilkins

Yes. Though... That could be viewed totally differently as poor communication and likely a manifestation of past and existing problems in an organisation.

Reply to
Richard Smith

Yes. Though... That could be viewed totally differently as poor communication and likely a manifestation of past and existing problems in an organisation.

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This is the convention he blindly followed:

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"There is a convention that bolts should be installed so that their shanks point inward towards the center of the aircraft, backward towards the tail, or downward such that gravity will tend to hold the bolt in place if the nut falls off for some reason. This basic rule makes inspection easier and seems logical in the case of a downward orientation, but if clearances or other important considerations dictate some other orientation, no sleep should be lost over violating the rule."

I don't remember where I read the story, or the details of the failure. The plane may have been a military prototype, I don't think it was an airliner.

The aircraft radio prototypes I built had to conform to structural rules, such as not breaking loose and flying forward in a survivable crash.

Reply to
Jim Wilkins

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