[motox]

subway
gas rod i use is RG45

[subwayrocket]

subway
i have repaired plenty of two stroke pipes and
have found that they weld better with OA if they
are used then they do with TIG. seems the open flame tends to clean
in inside contaminates off better.
craig

Yeah the inside soot was my concern. I heated the area with a hand torch , then got inside there with a small wire brush, acetone then sand paper folded over an angled dental pick kinda thing, repeated that until the OCD let go...haha. I was worried about contamination on the back side wicking up through but that didn't happen.
Clean Clean Clean ...as Jody says

[MosquitoMoto]

Hey well done, Sub.

I am very familiar with two stroke zorst and they don't call them 'stinkies' for nothing. Always so contaminated inside with oil and soot. I guess the up side of that is you seldom ex see a 2T expansion chamber corrode from the inside out.

Good job. Owner must be happy. Love that you are doing useful stuff as soon as you can, that's my aim, too.


Kym

[subwayrocket]

Tnx much Kym . Yeah, the plan was to just practice a few months, but then a broken radiator tab on the daughters bike and I had to jump in the fryin pan ...last week, my buddies Jeep dog leg quarter panel, then this pipe. I just won't do anything that someone's safety or life is hanging off...not til i'm doing this quite a bit longer . Someone inquired about a frame ...passed on that .

[MosquitoMoto]

I just won't do anything that someone's safety or life is hanging off...not til i'm doing this quite a bit longer . Someone inquired about a frame ...passed on that .

Yeah, I've been asked to do frame loops and a seat base for a Cafe Racer build but will hold off awhile until I am feeling really confident and have 'destruction tested' some of my own stuff. You are exactly right...not comfortable just yet sending someone out there to ride on a part that I have built. Confidence to do that will come with more seat time.


Kym

[Otto Nobedder]

Had another go-round with Stress corrosion cracking today.

DSCF0023.JPG (95.24 KiB) Viewed 1735 times

It wasn't interesting until I ground halfway through it. It later consolidated back in to one line. Here it is, ground through.

DSCF0032.JPG (97.54 KiB) Viewed 1735 times

and with a root pass in.

DSCF0034.JPG (94.16 KiB) Viewed 1735 times

My welds were all great today. This morning I took the last of the pills Dr. Sullivan gave me when he pulled my tooth. I was "in the zone" and "one with the puddle" and all that...

I was able to transcend dental medication.

Steve S

[ex framie]

Steve,
Theres far too much transending in your life
Nice job btw.

[Otto Nobedder]

Hell, how many chances will I get in my life to use those words and mean it?

Steve S

[Otto Nobedder]

Or, I could say I was in a "trance, on dental medication."



Steve S

[Otto Nobedder]

Here it is, filled up, BTW.

DSCF0038.JPG (80.93 KiB) Viewed 1737 times

It's interesting filling a concavity... Rod feed is constantly changing.

Steve S

[subwayrocket]

My dentist gives the the gas ...haha then no dental procedure is a problem.
Nice welds !

[nathan]

Or, I could say I was in a "trance, on dental medication."



Steve S

I always wanted to weld high lol

What was your cleaning procedure after that dpt?

[Otto Nobedder]

...

What was your cleaning procedure after that dpt?

I was grinding through about 7/16, so I would grind a bit, and DP again to be sure I was following the damage all the way through. Between stages, I just wiped up the excess developer and kept grinding. When it was time to weld, I used first the light Naptha spray that comes with the dye-kit, then brake parts cleaner (NON-CHLORINATED!), then a good blow-dry with dry nitrogen.

Steve S

[nathan]

...

What was your cleaning procedure after that dpt?

I was grinding through about 7/16, so I would grind a bit, and DP again to be sure I was following the damage all the way through. Between stages, I just wiped up the excess developer and kept grinding. When it was time to weld, I used first the light Naptha spray that comes with the dye-kit, then brake parts cleaner (NON-CHLORINATED!), then a good blow-dry with dry nitrogen.

Steve S

That's why I asked. I KNEW it would be more interesting than "acetone and scotchbrite."

Looks like a big part, how did you do the purge?

[Otto Nobedder]

Nathan, it was a huge part... The outer vessel of a 15K gallon vacuum-jacket vessel for liquid hydrogen. Back-purge was achieved by pulling full vacuum, then breaking vacuum with dry nitrogen before I ever started grinding (thus I'm starting with a 99.99% nitrogen atmosphere behind the weld). Then, 20 CFH nitrogen was plumbed to the vessel through the vacuum thermocouple port, and exhausted through a "blow-out plate" safety device. Argon would not be practical from a financial standpoint due to the volume, and this weld does not fall under any mandatory code, so nitrogen was more than sufficient.

Steve S

[kiwi2wheels]

Nathan, it was a huge part... The outer vessel of a 15K gallon vacuum-jacket vessel for liquid hydrogen. Back-purge was achieved by pulling full vacuum, then breaking vacuum with dry nitrogen before I ever started grinding (thus I'm starting with a 99.99% nitrogen atmosphere behind the weld). Then, 20 CFH nitrogen was plumbed to the vessel through the vacuum thermocouple port, and exhausted through a "blow-out plate" safety device. Argon would not be practical from a financial standpoint due to the volume, and this weld does not fall under any mandatory code, so nitrogen was more than sufficient.

Steve S

Steve ,

Question please, how did you become aware of the crack, and then locate it ? And was this in a mounting area ?

[Otto Nobedder]

Steve ,

Question please, how did you become aware of the crack, and then locate it ? And was this in a mounting area ?

This trailer had been in our shop 16 months ago for vacuum issues, with the same problem in the same general area. It came in this time for regulatory retest, and had poor vacuum on arrival. This was a first indication. Also, the CSS phenomenon has become common enough on these trailers that investigating that area (the rear head) is now automatic. Locating it was done through helium leak detection. With the vessel under vacuum, a mass-spectrometer tuned specifically for helium is attached to a vacuum pump. Then, I introduce helium to ever-smaller zones on the rear head, getting each time either a positive or negative indication telling me if there's a leak in that area.

This most common location for these cracks is a load-spreading structure that attaches the inner cargo tank to the outer vessel, for longitudinal support. It transfers inertia from braking and acceleration from the cargo vessel to a broad area of the rear head, so it sees constant flexing... the "stress" in stress-corrosion cracking. The cracks also tend to prefer to start at weld grain boundaries, so I almost always find them under welded structure, sometimes in a stand-alone seam weld, and rarely out in open unwelded material.

I'll try to remember to get a picture of the overall structure the next time one is sandblasted (so the client logo does not get published with the picture).

Steve S

[ex framie]

Interesting stuff that helium leak detector.
They were trialing something similar to find fuel leak origins in the F-111 fuel tanks.
They were getting good results iirc.

[Otto Nobedder]

Interesting stuff that helium leak detector.
They were trialing something similar to find fuel leak origins in the F-111 fuel tanks.
They were getting good results iirc.

Sound plan, as it works in reverse, too. A tank can be pressurized with helium or helium/air blend, and the mass-spec used with a "sniffer", a wand with a controlled leak rate, to localize places helium is escaping. I actually built my own, by pinching shut then welding a piece of 1/2" X .049 wall stainless tube. It took several tries to have a weld that was "just" bad enough for the mass-spec pump to achieve full vacuum, but still leak helium at a high enough rate for instant detection.

Steve S

[ex framie]

They were using it in reverse, covering the outside of the tank seams, pressurising that and running a sniffer around the sealeant seams inside the tank. The thing about fuel leaks was the fuel could show up on the outside of the tank at point "A" but the actual entry point for the start of the leak could be several feet away inside ths tank. The helium seach method really saved a lot of time in searching and sealeant replacement in a very uncomfortable and unhealthy environment.

[Otto Nobedder]

That phenomenon tests your patience. I encountered an inner vessel leak where the actual crack was nearly five feet from the point the helium introduction indicated it, because it was travelling under a weldment. I had nearly five weeks putting my finger on that one.

Steve S

[ex framie]

Yep, fun eh.
I'd guess half of the fuel leaks I have chased on several types of aircraft did just that, except it was sealeant it was travelling under. And I wonder why my hair is a lot thinner and a whole lot whiter than it used to be.
Wish we had the technology 35 years ago, would have saved a lot of work.

So in the case you mentioned above did that mean you had 5ft of weld to replace?

[nathan]

Here's what I welded today. Sorry for the long post, im a little excited lol

I have some family friends that cast aluminum ant hills and turn them into beautiful sculptures. Real quality work. G7 Artworks, they have a Facebook page if you're interested in seeing some of their pieces.

Anyways, they had a BIG mold that came out in six or so pieces. Well, last weekend I went to their house to try brazing it back together. I used flux coated brass and oxy acetylene to fail the first time.

I did some looking around and found out that my brass melted hotter than their aluminum, smooth move. That's okay, though; someone with a brain already had this problem, and, lucky for me, they work at Hobart. They made a low temp rod that's mostly zinc.

I had pretty good success with this rod on a few smaller pieces, but the big piece was 50"X35"X16" high, and would re-break under its own weight. So I gave up after six hours and had them come over to my shop today so I could try something.

I got some 1/8" 4043 stick rods and got a killer deal on some 3/32" 4043 TIG rod. It's funny, I'm one of two people in my department at work that knows you can stick weld aluminum, or that you can TIG it on DC.

Anyways, stick welding aluminum is awesome. Of course, I was just welding little pencil-sized pieces, and not any long beads, but that stuff lights up and feeds like a dream.

And there were bits where I needed some more control, so I just lit up the scratch start TIG and filled it right up. I'm pretty happy. The whole thing took about two hours, and I fixed the big casting and five or six other smaller ones. The customers were almost giddy, because they stand to make some good money on that big piece. I think I didn't make a cash profit off the job, but I got a bunch of materials left over, a very happy customer that will probably be back, and it was FUN!

Sorry there's no pics of the actual welds. They were pretty much tack welds, so nothing really fancy.

[ex framie]

Those sculptures are fantastic.
They are however bloody hard on the ants

[kiwi2wheels]

This trailer had been in our shop 16 months ago for vacuum issues, ................ remember to get a picture of the overall structure the next time one is sandblasted (so the client logo does not get published with the picture).

Steve S

Thank you Steve. That is quite a procedure.