Welding Tips and Tricks

Well, well,

The boss asked me how I felt about closing the vessel I'm repairing. I'm fine with that, but it means an ASME sect. IX code test, x-ray.

Closing the vessel means re-installing the circle we cut out of the front head. It'll be 3/8" SS, TIG all the way, with a backer, in 5G position, so it should be a piece of cake.

I don't know at the moment what the weld test will be to qualify for this, though. I've never had to work within this code.

Steve

Hi,

Do you have access to a copy of the Code? (most likely considering the work you do) I have a electronic copy from 2001 that I was given (ssshhhhh) I could email it to you if you would like (sssshhhhh).

mick

As long as it's clear that it's outdated, and for "reference purposes only", since it's my employer's responsibility to know what code sections apply...

We should be good.

Thanks, Mate!

Hey,

Im not sure if it is out of date but most of the time the changes are very minor. Ill send it through. Its good to be able to read this things for personal research perposes.

Mick .

Thanks, Mick,

This should make for an interesting study.

Steve

hey,

My pleasure, hope you can get some good info from it.

Mick

Is the vessel you are working on an ASME Stamped vessel?
If so is it a Section VIII, Div.1 or Div.2 vessel?

If you are welding on a ASME stamped vessel then your shop needs to be a ASME shop in order for the vessel to continue to be ASME after the repair. The repair would require you to have a "R" stamp.
If the vessel has a National Board number then you can contact the Nation Board to aquire the original build file on the vessel.
The vessel will need to be hydro tested at 1.3 times MAWP and witnessed by a ASME Authorized Inspector who will sign the new "R" stamp data report upon inspection.

5G welding is a AWS standard. ASME welding is performed under Section IX requirements. Whatever proceedure you use has to have a qualified WPS and PQR for the welder doing the the welding. You will need to maintain welder logs as well.

Any new materials you added to the vessel will require MTR's for traceability. You need to have your shop travelers filled out as well.

More then likely to comply with the Code this weld is going to required 100% NDE. This may depend on where you cut the hole. All formed heads that are spliced have the the splice joint 100% X-Rayed in order to used 100% joint efficiency.

I don't know what the service this vessel is used in but since it is SS I assume it is some type of corrosive service. This would require purging so you do not get surgar inside since you cannot back weld it. I assume you cannot backweld it because you had to cut a access hole in the vessel in the first place?

If I you I would suggest installing a manway assembly. This way the vessel can be accessed again if needed and you can have a few more weld options.
Calculations for this would have to be done. Addition of a manway may required additional reinforcement.

Shane M,

Thanks. That's good information.

We have an "R" stamp, and operate under several exemptions.

A manway is absolutely out of the question-- The service is liquid hydrogen.

The "hydro" is done with dry nitrogen gas at 1.25 MAWP. The vessel is vacuum-jacketed, so vacuum monitoring during the retest is the failure detection mode. The procedure doesn't call a "fail" unless vacuum rises 200 microns, but that's a bullshit number. During a workday (the general duration of the total test in practical terms, as after a 10-minute hold at 1.25 MAWP, pressure is reduced to MAWP and held while every connection external to the vessel is leak-tested), a vacuum rise of 5 microns due to ambient temperature change is unusual.

I now have a copy of section IX, and have been studying it. This is the first time it has applied to me, as all repairs I've done to now were external to the vessel.

We have a local radiographer, and are aware of that requirement, both for the repair and the closing of the head. The client requires it in places where the code does not specifically require it.

It will be back-welded as well. Now that I've put my finger on the leak (see "confined space entry" under "Welding Projects, plans, etc" for images and details) and know there is a FCAW opposite my leak, I have no choice but to open the outer vessel as well. The crack likely continues through the FCAW. There are details missing in that thread, as well, as the leak continues opposite the fillet in the image. And, yes, it's quite convenient to back-purge the weld from each side as required.

As I understand what I've studied so far, to close the head I'll need to certify on 3/8 SS GTAW with backing in 2G & 3G, and to make the repair I'm asked to certify 6G, though thickness hasn't become clear yet. The vessel is 3/16" in the area of the repair, so I would expect sch. 40. (The actual repair welds will be 1G and 4G, however).

Thanks for your input, and I'd like to hear what you digest from this information.

Steve S.

Steve,

I am glad to hear you have the "R" stamp. I was concerned about that when I first read your post.

I did not realize this was liquid hydrogen, that changes things as you said.
We too have have clients that require NDE sometimes where the Code may not. We usually refer to these as "information shots".

A far as you WPS goes and welding certs I can tell you how we do ours. Our processes are qualified using pieces of plate welded in the flat position using whatever metals you intent to weld. We do the welding and then send the coupon to a lab for pull testing. Once the PQR is approved we then use that process for whatever position we are welding in. I can however understand that they would want you to certify 6G just make sure of your capabilities in all postions.

My knowledge of ASME Code is limited when it applies to vessels outside of what we manufacture. We manufacture single wall pressusre vessels that usually contain water or fuels. We do not manufacture anything rated for more the one atmosphereic pressure of vaccum. The majority of our welding is submerged arc. So I don't know if I can be a lot of help with your application but I do have an engineer with 40 years worth full knowlege of the Code and I would be glad to ask him any questions you have if I do not know the answer.

Shane

Shane,

We have a guy in the Houston facility that covers code compliance for us, but in Houston they do atmospheric trailers in carbon steel, so he's having to work with the client to establish not only code compliance but the specific customer requirements.

I was trying to avoid being surprised by anything when I get the requirements, but there are only two other shops that I'm aware of in North America doing LHY, and they're not going to share.

Between what I've read, and what you've said, I probably have as good a handle on this as I can regarding the code, and I'll just have to wait and see if the client requirements surprise me in any way. I'm trying to get the applicable WPSs out of them, but there's a mess of company politics involved, so I may have to use a generic WPS for the materials and let the radiology speak for the results.

Thanks again,

Steve S

Steve,

It sounds like you have a good handle on it. I don't think you will be an for any surprises.
Let me know if I can help.

Shane

Shane M,

The word I have back from Houston, is that 6G test will qualify me for all positions to 3/8", so that's finally covered, according to the code guy. Prolly do my coupon tomorrow, if this head-cold eases up.

I finally put a finger on the leak, as shown in fresh pictures at the end of the thread "confined space entry" under "projects".

With the picture, they've decided to get engineering involved... The wall thickness is 3/16, so I should be able to do a full-pen weld easy enough, but I'm guessing they'll still want me to open the outer vessel and back-weld it. It's their nickel, and the x-ray will be easier if I do!

I couldn't believe that leak was 38 full inches from where I detected it!

Steve S.

It took those screwballs long enough, but I FINALLY have my ASME cert, for all positions to 1/2" thick.

Steve S.

I am new to the forum and just stumbled on this thread but could one of the guys that has that copy of Sec. IX ASME code send it to me. My shop is getting a new customer that requires us to be code certified and I have to go take that test in a few weeks. Just trying to see what I am getting into. Thanks in advance

Hey mate,

Personal Message me an email address and ill take care of it. My one is an outdated copy but it'll get ya started.

Mick

Awesome will do. Much appreciated!

Hey,

at work now. Will fire it off tonight.

Mick