[Otto Nobedder]

Our li'l shop now needs to obtain it's own "R" stamp.

Guess who's picked to weld the "R" stamp demonstration? I have to do a nozzle weld (GTAW), a short longitudinal weld (GMAW), a short circumference weld (GMAW), and a 6" square patch weld in the middle of the circumference weld (GMAW), all on one piece.

Here's the rub... Our primary client specifies GTAW for all inner-vessel repairs, so that's all I've done. The GMAW is a bit of a mystery to me. I have a drawing and the material, but for some stupid reason I was not given a WPS, and the guy who has it is on vacation!

I have no issue with the nozzle weld, but the GMAW welds...

This is all 1/4" 304SS rolled to 36"radius. The weld symbol in the drawing says "backing" with V-groove. Without a WPS, I have no idea if the backing is ceramic tape (which I suspect), or a backing bar/strip. I also have no information about accepted gaps and lands, or even machine parameters.

I'm not striking an arc until I have this imformation, but I know at least one person on here has extensive experience with "R" certification, and I hope you can give me a clue what to expect.

Steve S

[Braehill]

Steve,
I would assume this is because of the CO2 trailers and the budding Microbulk business. These vessels don't qualify for the exemption that an atmospheric trailer falls under. Both are fairly new additions that came about as I was getting into the plant side of things, although I did have some exposure to the Microbulk trucks, but they were too new to need vessel repairs.

The only piping repair I did was on a pressure build coil on a Nitrogen Microbulk and if you show pictures of that repair on here I'll deny it all day. Actually, I think it got replaced under warranty later. It was mounted on the drivers side above the fender and the leak was inside of the 180* bend facing the tank. I had an old #18 torch with full sized consumables and they refused to let me take it off for repairs, not proud of that one. JB weld might have been prettier.

Len

[Otto Nobedder]

No, Len,

It has nothing to do with the CO2. I'm not sure the demo I'm given will qualify me/us for those, anyway.

This is because our new masters demand we become an indepentently certified R-stamp shop. I'm fine with that, as I never liked my certs being held by a remote shop, and at their whim. I'm frustrated at the peicemeal approach, and pissed at the lack of both warning and information.

Steve S

[Superiorwelding]

Steve,
I do not hold a "R" stamp nor do I know a whole lot about it but I do know that you cannot take your test unless you have the WPS to weld to (you already know that). I do know holding a R stamp is a pain and add quite a few challenges and paperwork. Gotta love paperwork.

I can, however, help you with the GMAW process a little. I personally have not taken a SS GMAW test but have watch others and of course have welded it quite a bit. Your backing could be a number of things as you have noted. I have more questions than I should probably ask for now but I will ask these, do you get to practice first and is it a NDT?
-Jonathan

[Otto Nobedder]

Turns out, this is not a test coupon. It is literally what it was described to me as... A demonstration piece. To show we understand the practices and procedures.

I did finally get a WPS, which I did not use. The WPS was for manufacturing, where you have rollers and all work is done 1G, and gave spray-arc settings. All I was required to follow was the bevels, land, gaps, and backing (and ceramic tape is okay).

So I did almost all of the GMAW work today. The sample was 1/4" 304SS, 36" by 12", rolled to 36" radius, with one longitudinal weld (12") and one circumference weld of 18" on one half of the sample. (The other half gets a GTAW nozzle weld of 2" sch. 40.) In the middle of the circumference weld, I had to cut out a 6X6 section and weld in a patch. When it's complete, I'll get a pic.

I do have pics of the 6X6 cutout, including an etch. Etch first, then face, then root (ceramic tape) side.

Steve S

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[GreinTime]

What is an "R" Stamp?

[Braehill]

It's basically a stamp that's let's someone know that a pressure vessel has been repaired by a certified repair company.


Sent from my iPhone using Tapatalk

[Otto Nobedder]

What is an "R" Stamp?

Under ASME code, any pressure vessel that falls under the code can only be repaired by an ASME approved shop.

The "R" stamp is literally a stamp used on a data plate with the shop's "National Board Number" and other data to certify the repair and make it traceable to the shop and the individual(s) responsible.

Steve S

[GreinTime]

I gotcha. I blame you two any time I hear of something happening with gas trailers. Weld failed: Must have been that Steve guy from the repair shop. Over/underfilled the tank: That damn Len guy from western PA.

[Otto Nobedder]

Sam,

You would be shocked to see some of the "repairs" done to the atmospheric trailers... You just know the terminal manager didn't want to hire a rig man to fix it, and asked his mechanic, "do you think you can fix it?" And you know some job-scared mechanic is going to say, "sure, I'll give it a go..."

I regularly requisition "turd-polish" in the 55-gallon drum.

Steve S

P.S. Thank goodness they don't try that with they LHY fleet. Though I had an Aire Liquide trailer come in with a sweat-sock fix to a leaking PB coil...

[Superiorwelding]

Steve,
Very nice my friend! Great profile and penetration. Can you share all your welding specs for our benefit?

Sam,
Every time I see one of their trucks going down the highway I quickly get around it, never know when a weld will fail or the bad gas mixture explodes.
-Jonathan

[Otto Nobedder]

Hey, Jonathan, thanks!

This was all traceable 304SS 1/4" rolled to 36" radius (I guess I already said that) beveled approx. 37*/side to a 1/16" land, TIG tacked with 1/8" gap, and tacks buffed flat on the back, feathered on the front.

Ceramic tape was oversize for the weld, but was what I had... Would tolerate a full 1/2" root, but I ran with it.

Machine was Millermatic 252 using .035 E308L, set at 20.8V and 350IPM for short-circuit. Weld was done in two passes. The root was focused on keeping the arc at the front edge of the puddle with a sharp (25*?) drag, so the arc was almost "below" the lower surface, and came out generally flat on the top. I did grind the root, treating it just as if it were going to be x-rayed, and did the cap in one slow pass, explaining the ripples. There was a slight occillation, but no weave. All welds were done in the flat position.

On a side note, It was a last minute decision to try to etch the section I cut out for the required patch. I'd cut it with a zip-wheel, so started pretty flat. Hit it with a DA, first with 180, then 600, and the only acid I had on hand was ZEP brand commercial toilet-bowl cleaner (hydrochloric). Took about three hours for the result you see.

Steve S

[Braehill]

@Steve,
The wet rag (sock in this case) trick was in the driver's handbook when I started, and we will still use in on the LHY sphere if a leak isn't able to be isolated by valving it out.

As far as the in house piping repairs go for liquid trailers, it happens a lot more than you think and a lot of the piping in the rear cabinets are done by terminal mechanics. Very few of the flex pipe sections last from rehab to rehab on these trailers since they strecth those intervals out so far now. Some of these guys are exelent welders and come from that world, while others come from the mechanical side and have minumal welding skills. They look for techs that have welding skills over ones who don't, if you think about it our techs are kept in house to do specialized repairs that can't be done at just any truck repair shop. You'll still get that turd on many occasions though because the guy in the shop in the middle of the night on Saturday might not be the welder, but the mechanic.

Len

[Wes917]

Steve,

Looks good from here! Thanks for the write up, love seeing what others are doing.

[Otto Nobedder]

@ Len,

I get the wet sock emergency fix. Works good. But...

This trailer had remained in service with the wet sock until the sock was badly degraded. It didn't come to the shop until it had a vacuum issue and built pressure on the road... twice... and when the guy before me couldn't find a leak, they took it out again and it built pressure again.

The story of the vacuum leak is an epic unto itself, but they weren't going to fix the PB coil until a major fail. It was only fixed because it was in the shop for a major repair.

That's a shitty approach to maintenance, and I thank God your outfit has more sense.

Steve S

[Braehill]

I just talked about a repair that i did on the pressure build coil of the Microbulk truck. They needed the truck for a customer who was running out and if it could be patched together enough to go that day, that was all they wanted. That truck was moved monthes later to another terminal and that "temporary" repair went with it. I just hope whoever finally fixed it didn't think that it got my best attempt at repairing it. Some days good enough is just that, good enough. The show must go on.

@Sam & Jonathan,
I'm trying to like you two, but you're making it awful hard.


Len

[Superiorwelding]

@Sam & Jonathan,
I'm trying to like you two, but you're making it awful hard.


Len

Same to you.
-Jonathan

[Rick_H]

I'm with the others looks great Steve.... Was that all with trimix gas?

Jonathan and Sam - you guys crack me up...lol

[Superiorwelding]

Rick,
We are Welding Tips & Tricks comic relief.
-Jonathan

[GreinTime]

I've been actively trolling my father since day 1. It's become a favorite pastime of mine!!

[Otto Nobedder]

I'm with the others looks great Steve.... Was that all with trimix gas?

Jonathan and Sam - you guys crack me up...lol

Thanks, Rick,

Yes, it was standard tri-mix, 90/7.5/2

I'll sneak a few pictures of the finished product, after the nozzle is TIGged in and it's complete. It's a bit complicated for a piece that's visual ony. I welded it like it was the real deal, but it's a "demonstration" piece, primarily as proof we can do all the crap we say we can do. Everyone to be coded will have to pass individual tests. I should still be current, so am exempt from the stainless test, but I may be asked to certify in aluminum pipe in a 6G, and even possibly some AWS D1.1 stuff once we have our "R" stamp.

Steve S

[GreinTime]

You're a stamp!!

[jwright650]

Question about the ceramic backing....

Do you ever have any trouble with porosity when using ceramic backing? I ask because we used it a lot but I was always questioning the way they stored the stuff and if it was picking up moisture or not. We had random bouts with porosity and I blamed it on the backing or actually the way that they stored it in the bottom of their desk.

We used it for CJPs similar to yours(just a lot thicker carbon steel materials), but we had access to the "other" side and would remove the backing and carbon arc the root back out and re-weld the second side. It saved time scarfing off a steel backing bar. There were instances where the engineer of record would require the backing to be removed due to it causing a stress raiser in cyclically loaded structures.

[weldin mike 27]

We use it, and on particularly wide gaps where the (cylindrical) backing pops into the gap a bit too much, we sometimes get porosity. (Or if the operator is careless)

[Otto Nobedder]

The only porosity issue I had was of my own making...

The ceramic tape sat in a corner without climate control for three years unused, and caused no porosity that I could detect,

"But"... I failed to set the friggin' Millermatic 252 for post-flow (doh!), so every tail-off had to be ground. I'm too used to MIG being simple, and forgot I had a post-flow option on the machine I chose to have calibrated.

Steve S