ASME IX QW-404 (AWS CLASS.)

By jon20013 (*****)

Date 06-24-2004 17:59

No problem. The WPS will need to be revised but not requalified. Suggest writing the revised WPS as ER3XX-X and under the range side of the WPS state "Any F6, A8" WFM (WFM = weld filler material). Personally for welding 304 I would use ER308. Looks to me like your WPS will work with just an editorial revision.

By swnorris (****)

Date 06-24-2004 20:10

Hi Deleo,

Volume 4, Seventh Edition of the Welding Handbook, an AWS publication, supports jon20013's preference for welding 304 with ER308. The recommended filler metals table indicates that, depending on the process, E308, ER308, and E308T-X for type 304 stainless. Also, recommended filler metals for Type 304L stainless, depending on the process, are E308L, E347, ER308L, ER347, E308LT-X, or E347T-X.
The suffix "x" is for the FCAW process and is designated with a 1, 2, or 3, which indicates the recommended type of external shielding gas for the process. 1 indicates CO2, 2 indicates Ar + 2% O2, and 3 indicates none, however other external shielding gases recommended by the electrode manufacturer can also be used.

By jon20013 (*****)

Date 06-24-2004 20:17

Thanks Scott. Having said that, there's no reason I can think of other than cost that would "prohibit" use of ER316L for welding 304, depending on local specifications, naturally.

By deleo Date 06-26-2004 15:32

Friends,

Thanks for the info.

By flighter Date 08-20-2005 14:22

Friend,

I do not think so. in QW-431 detailly explained the F-Number: "the F-Number grouping OF elecs ...is based essentially on their USABILITY characteristics, ...This grouping is made to reduce the number of welding procedure and performance qual'ns. where this CAN LOGICALLY BE DONE. The grouping DOES NOT IMPLY that base metals or filler metals in a group may be INDISCRIMINATEDLY substituted for ....without consideration of the COMPATIBILITY of the base and filler metals from the standpoint of metallurgical properties, .....

for your reference please and hope helpful to you
Flighter

By jon20013 (*****)

Date 08-20-2005 15:04

Regardless, the answer to his question remains the same; yes.

By - Date 08-20-2005 17:06

Flighter,
Look at QW-404.4 and QW-404.5 of Sec. IX. No requalification is required if the A-number and the F-number are the same. You are taking QW-431 out of context.

Chuck

By - Date 08-20-2005 16:21

swnorris,
Unless I'm missing something here, I respectfully disagree with the FCAW part of your answer. According to ANSI/AWS A5.22, 1995 edition,
"Specification for Stainless Steel Electrodes for Flux Cored Arc Welding and Stainless Steel Flux Cored Rods for Gas Tungsten Arc Welding", Table 2 lists the recommended gas shielding for the FCAW processes. I agree that the "1" designating the gas shielding is for CO2, but there is no "2" designation for FCAW listed in the Code book, only 1,3,4,and 5. The "3" designation is a non-shielding FCAW, the "4" designation is for 75-80% Ar and remainder CO2, and the "5" designation is 100% argon for the GTAW process. I realize what the Welding Handbook says, but the Code Book for FCAW differs from that. In A2.3.3 of the Code Book it states,"Following the position indicator and the dash, are the numerals "1", "3", "4", or "5", or the letter "G". The Code Book makes no mention of a "2" designation. except to say, "In ANSI/AWS A5.22-80, stainless steel classifications for 98%Ar-2%CO2 gas shielding existed (EXXXT-2). The combination of a slag covering and this shielding gas has been found to be inappropriate for flux cored arc welding and the EXXXT-2 Classification has therefore been deleted from A5.22-95." Respectfully, 98%Ar-2%Co2 is definitely not recommended for FCAW welding of stainless steel. Also, the "-1" and "-4" gas designation are dual classified.

Chuck

By - Date 08-20-2005 16:48

P-numbers are a designation for base metals. Welding electrodes are classified as F-numbers and A-numbers. For a 308 and a 316, the F-number is 6 only if SFA-5.9 (bare wire) or SFA-5.22 (FCAW) is used. The F-number will be 5 if using SFA-5.4 (SMAW process). The A-number will be 8 for both. There is no requalification involved.

A lot of people use a 316 series to weld 304 because the added moly aids in resisting pitting corrosion.

Chuck

By pipewelder_1999 (****)

Date 08-20-2005 18:56

Mr. Meadows,

Are there any situation in which type 304/308 is more resistant to corrosion than 316 ? I am almost positive I read in a corrosion table somewhere that there were certain conditions where 304/308 fared better.

Of course I coulda dreamed it :)

Thanks

Gerald

By pipewelder_1999 (****)

Date 08-20-2005 19:00

If my research is correct, It is Nitric acid. This is based on the Moly content. There may be other conditions too.

By - Date 08-20-2005 21:19

Gerald,
What is this "Mr. Meadows" thing? It is always just "Chuck". :-)
If you are talking about a 304 and 308 base metal, then there are applications where that combination is more corrosion resistant that a 316, and one would be a urea application due to the ferrite content due to the moly. Speaking of Nitric acid (HNO3), to compare the base metals (304/308 and 316), you have to consider the concentration % and the temperature of the nitric acid. Both have virtually the same corrosion resistance all the way across the board except when the HNO3 is at 80% and the temp is at 106C, which is the boiling point for the acid at that concentration % and temperature. At this solution, the 304 has a serious corrosion rate (over 1mm/year) which is considered unusable. The 316, in this same solution has corrosion rate of 0.1-1.0 mm/year with a slight chance of IG (intergranular corrosion). This would be cosidered usable, but not corrosion proof. The higher allowable Ni content, plus the 2-3% of Mo in the 316 make it more corrosion resistant in virually all applications than the 304 or 308. I'm sure there are some circumstance where the concentration and temperature are adjusted where the 304/308 might have a slight advantage, but not in most cases.

Chuck

By pipewelder_1999 (****)

Date 08-22-2005 13:59

Here is something from NIDI that I found relating to the use of 316 vs 304 in Nitric acid environments. http://www.nidi.org/index.cfm/ci_id/10626/la_id/1.htm

In many field applications I have heard welders say "its ok as long as it is an upgrade" Meaning usually a higher "number" . I have always said "NO" to that thinking. Since each grade of stainless or other materials have certian characteristics, then welders, inspectors, project managers etc, should stay away from making welding engineering decisions. If the project engineer says its OK then I stop arguing and record the details of what was discussed and decided.

Anyway Chuck, that is some information that seems to support what I thought as fact. This would mean to me , If joining two pieces of 304 together, use 308. If the piping specifications call for 304/308, 316 may not be a suitable replacement.

Have a good one

Gerald

By jon20013 (*****)

Date 08-22-2005 14:48

Gerald, with all due respect, getting back to the original question that was posed, the answer is still "yes."

By pipewelder_1999 (****)

Date 08-22-2005 14:58

I thought that was what I was adding some information about.

Randomly changing the filler metal to 316 from 304 would not be a decision to be made based on it being allowed by the code.

I may still be missing out on what the question is. I understand his question about the code and if it is within the limits of the code and I agree that it is fully fine as defined by section IX. I just wanted to point out that (I don't think) 316 is a suitable replacement for 304/308 without looking into the intended application of the weld.

The WPS being within or not within code has probably had little to do with weld related failures, but again, only an opinion.

GA

By jon20013 (*****)

Date 08-22-2005 15:15

Gerald, the original question read:

"Can ER316L be changed to ER308 in WPS without requalified the WPS or can ER316L be used as filler since its P-number and A-number are the same which is 6 and 5.9 respectively, in order to weld the base metal of Stainless Steel 304."

There may be many reasons why the engineer would not allow this to be done, but just looking at the code requirements, I would have to say that the WPS could be revised without requalification.

So, for what it's worth, my answer would still be "yes."

By pipewelder_1999 (****)

Date 08-22-2005 15:56

I agree that it is ok to do.

I guess I read the part ...

"or can ER316L be used as filler since its P-number and A-number are the same which is 6 and 5.9 respectively, in order to weld the base metal of Stainless Steel 304."

And read it as "is it ok to use 316 instead of 304 since the numbers are the same." And as I read the responses from Chuck, I am learning more .

I agree that in no case is WPS requalification required.

Gerald

By jon20013 (*****)

Date 08-22-2005 16:17

Gerald, I think Chuck joining the Forum is one of the best things to happen since you joined the Forum! It's all about exchanging ideas and learning together. It seems most of us have our own little "niche" if you will...

By pipewelder_1999 (****)

Date 08-22-2005 16:34

I don't know about the part about me but I sure appreciate his willingness to share knowledge.

I am working as a CAD draftsman now and this is where I go to stay at least as sharp as a butter knife ! Not much welding related stuff at work any more.

Have a good one
Gerald

By jon20013 (*****)

Date 08-22-2005 17:01

Gerald, don't underestimate yourself! You've provided loads and loads of very valuable insight to many in the Forum (including me!) and your website is packed with wonderful welding related goodies!

By - Date 08-22-2005 15:00

Gerald,
The article you referenced used 60% Nitric acid and boiling points. At 60% and BP (boiling point) which is 121C, sigma is not a concern. Sigma will not be a major concern until reaching extended periods of time at approx. 1400F. At 60% concentration, Nitric acid boils long before that. As a matter of fact, the maximum temp. for boiling Nitric acid is at 65% concentration, and 121C. Again, the concentration % and temperature is what makes the Nitric acid corrositivity ranges. For example, at 5% concentration and 290C, the 304 and the 316 are considered "unusable" due to the expected corrosion rate of over 1.0mm/year. Yet, at 80% concentration and 106C (BP) the 304 is considered "unusable" due to the expected corrosion rate of over 1.0mm/year. Very, very seldom is Nitric acid ever exposed to a constant temperature in the 1400F range, where sigma will form over an extend time. I certainly agree that sigma is more prevalent in a moly bearing steel like 316, but only at extended periods of sigma temperatures. Actually, joinin a piece of 304 using a 316 filler will give you better corrosion protection in Nitric acid except ONLY in a sigma temperature, which is a rare concentration % and temperature.

Chuck

By pipewelder_1999 (****)

Date 08-22-2005 15:14

Thanks chuck,

That helps me understand a little more about what I read. I had come in contact with similar informaation while working on a urea to ammonia plant a few years back and only remembered it when I read this post. I have a little better understanding now.

Hopefully I haven't confused things too much.

Thanks again

Gerald

By - Date 08-22-2005 15:46

Gerald,
That is why I mentioned urea not being a good candidate for a 316 series material. Urea is a high temperature process and sigma will attack a 316, due to the lower Cr. and higher moly, quicker than a 304. You have not confused things at all. Rather, in certain applications you are totally correct. The main thing to remember is that the % of concentration and the temperature are the driving forces for corrosivity of virtually all acid environments.

Chuck

By MBSims

Date 08-22-2005 03:22

Chuck,

The F-number for SFA 5.4 is 5.

By - Date 08-22-2005 03:32

Marty,
Right, I need to pay more attention to my typing. Sorry.

Chuck