I should mention, I also suggested they do the leak repairs with a high grade 2 part marine epoxy. That stuff is tough as nails but I wonder how it would react to the 500 degree temps and the asphalt chemistry. Thoughts appreciated.
My experience with 20,000 gal. tanks, like the one you describe, is that after steaming for 3-4 days, we would open up the manhole and if a sniffer indicated it was safe, send someone in through the manhole, with air-supplied breathing apparatus, to the leak area, to scale the inside to determine the extent of corrosion. If most of the tank was corroded badly, we would recommend replacement, or, refuse repair. If most of the structural thickness, was still intact, we would resume steaming, and cut out large sections, back to sound steel, and weld in new sections, rather than patch. ( I don't recall working on an asphalt tank, since most of these were oil, diesel, gasoline, or natural gas).
Since it sounds as though this is a very old, and poorly repaired tank, the owners would probably be better advised to spend 7-10 thousand on a used tank in their area, and get reliable service until replacement is necessary. (Newer tanks have outer insulation layers, and better heating systems, and operate more economically).
Northweldor-
Again, thank you for your insights. The repair procedures you described are about what I would expect in a plant that was properly maintained with a comprehensive safety program in place. The one I have been dealing with would not really fall into that category. The owners have put off proper maintenance for what looks like the last 40 years- I mean like everything looks like it's leaking or falling apart and held together with shoe strings and duct tape, never one day further away from something breaking down needing an emergency and temporary fix. I contacted an asphalt tank manufacturer yesterday and got to speak with a couple of guys there including their head welder/tank repair guy. He assured me if the tank was brought down to cold, properly vented with a blower, the asphalt would be too cold to ever ignite vapors- the dangerous element. He said I could expect smoke and small fires when welding but with the asphalt cold and no vapors there was no danger and he'd have no concern doing the repairs. He did mention that if the tank had ever been used to store anything else [he mentioned diesel] then the repair were an absolute no go. Considering the lack of controls in place at the plant, my lack of confidence in their safety program and maintenance and the unknowns of the tanks history I decided to take a pass. I'll lose the larger job I was angling for, but didn't yet have, but not my life which I value a little more than a good paycheck. They'll just have to find a welder hungrier than I am. Thanks again.
Been following this thread.... Don't know enough to comment technically...
Glad you are taking a pass :)
Lawrence-
Since it's my own thread I suppose I can jump to another issue and it's a question I think you'd have an answer to readily. Being asked to weld some bracket supports to a stair guardrail. The guardrail is old- historical library- the GC has no idea if the rail is steel or wrought iron and I haven't put a grinder to it to do a spark test [there are some existing legs that will be removed I can test on without damaging anything]. Checked the search bar some but haven't found my answer. Can I weld an A36 mild steel bracket to wrought iron? If so, can you advise on best approach? Will be done in the shop. Specs call out AWS D1.1 but I don't expect the Owner [City] is going to be too picky or require a procedure qualification [my assumption is they only need to know it's going to be strong enough for code loads ie. 200# in any direction]. Is this something that you can respond to? Thanks in advance.
I hope Al Moore is following this... He has more experience with old steel.... But that's to be expected because he I believe was actually around when the first iron meteorites were hammered into trinkets for the Pharos.
The whole D1 thing makes it complicated.... I can't think of a work-around for unlisted metals like you describe that excludes procedure qualification.
If it was in my front yard, I would do exactly what it looks like you are doing... Take some scrap cut from the thing and experiment... It's possible that a even braze repair could be used if the iron won't weld.. and could be painted or bees wax treated to look like original.
For old ornamental iron, I've used a pretty broad range of stuff, depending on what was at hand... 388, 309, Hastelloy W, for GTAW... A number of different *Eutectic* SMAW rods, silver braze with ox-fuel and GTAW with silver braze filler.
Sorry... That was a lot of words but not a lot of help.
Hopefully Al comes out of his cave
Depending upon the decorative pieces, some are cast and some are just forged. Most of either can be welded with a stainless or something like a 99 nickel. They can also be brazed. Many of the forged ones can be welded with any carbon steel electrode.
I have not been around as long as Al, but I haven't seen too much in the line of railings that was actually wrought iron. But, some of those older historic buildings have some pretty strange stuff on them. And notice, I did say, not too much. Yes, it is out there.
The choice will have more to do with after repair coloring and customer likes or dislikes.
Many specs will call out a code just to have one on things like this because neither the city officials nor the engineer have a clue what it is or how to find out and just want someone with some level of competence. Thankfully, they got you. Thus, more than just 'some level' of competence. Many that do much railing would just have done the bull in the china closet thing and buffaloed their way through then hoped for the best.
Often, the decorative parts are not as critical for strength as the main frame, posts, and connection points. As long as those are strong enough the space fillers are not usually as much of an issue. And, there can be strengthening items put in place to reinforce them. Without seeing it, pure speculation and opinion. Yep, we know what that is worth.
Good luck.
He Is In Control, Have a Great Day, Brent
Thanks for the input and feedback gentlemen. Since the repairs are intended to replace existing posts and it is probable qualifying a procedure per code would be expensive at best and very possibly not successful in any case, it may not make sense to approach the problem by welding. The railing [and the existing posts] are not degraded it is the post embedments that are loose in a degraded concrete stringer of the stairs. I will likely recommend the GC pursue a change order to remove the rail whole from the concrete stringer and re-build the stinger with the existing railing and posts that can be poured in place instead of just patching the concrete at the spalling which is what is causing the railing to be loose. Questionable welds at the posts do not serve any good purpose.
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