Dual certified 304/304L and its pressure ratings

Hi all,

I'm fairly new to this board, this will be my first post.
The question I'd like to ask deals with dual certified 304. I've already google-ed this topic a lot but I cant find a satisfying answer to my question.

Right now, the company I work for (we work in e.g. the (petro-)chemical industry) is making a new pipe spec for 304 material.
We didn't have any for 304 spec before, so I thought of, while making the new 304 spec, to use dual certified 304, since it's good available as such, and has almost the same parallels as 316/316L (for which we already had a spec).

Now, the one thing bothering me is that 304L flanges are limited (per ASME B16.5) to 425 deg C, while 304 flanges go up 1500 per ASME B16.5.
If you have dual certified 304/304L flanges, can you then 'just' use such dual certified flanges up to and above 425 deg C?

The second question (not that important but still interesting); what would you have to do if you want to use 304/304L piping systems beyond 1000F (~538 deg C)?
What values for stresses do you then use, how do you do the calculations?

In case, if you have missed this thread. See if it helps:
www.eng-tips.com/viewthread.cfm?qid=180920&page=14

After going through the thread I felt,
The dual certified material is better in the ranges that are overlapping and should not be used when the temperature is in the top fringe!
It kind of tries to please everyone

Rgds,

Hi shrivallabha,

Thank you kindly for your answer.
I already noticed that thread, but it doesn't mention anything about the temperature range 304/304L may operate in, regarding the limits of 304L flanges.
Hence my question is still open.

The post #4 by JamesKelly mentions Temperature suitability

Almost all "304" plate is dual certified. It may be 0.03 max carbon stuff dual certified 304L/304. This, meanins it has decent corrosion resistance as-welded and the tensile & yield properties of 304, at least near room temperature.1150F is in the creep range, for which you need dual certified 304/304H. This has a minimum of 0.04% carbon for strength, plus I think both grain size and minimum annealing temperatures. It is widely available.Dual certification is the common practice. The mill does not want to melt two or three different chemistries, i.e. 304L, 304 and 304H so they make two different chemistries do the work of these three. It is the magic of precise chemistry control by refining the melt in an Argon-Oxygen Decarburization vessel, where a little nitrogen brings up the yield strength of 304L to the requirements of 304. Great for room temperature but the dual-certified "L"grade is not usually considered strong enough for use in the creep-limited range.Clear as mud?

If you go by this post then you should avoid using Dual Certified Steel (L) at higher temperatures and should go for the other Dual Certified Steel(H).

See if this is of any help!

The post #4 by JamesKelly mentions Temperature suitability

Almost all "304" plate is dual certified. It may be 0.03 max carbon stuff dual certified 304L/304. This, meanins it has decent corrosion resistance as-welded and the tensile & yield properties of 304, at least near room temperature.1150F is in the creep range, for which you need dual certified 304/304H. This has a minimum of 0.04% carbon for strength, plus I think both grain size and minimum annealing temperatures. It is widely available.Dual certification is the common practice. The mill does not want to melt two or three different chemistries, i.e. 304L, 304 and 304H so they make two different chemistries do the work of these three. It is the magic of precise chemistry control by refining the melt in an Argon-Oxygen Decarburization vessel, where a little nitrogen brings up the yield strength of 304L to the requirements of 304. Great for room temperature but the dual-certified "L"grade is not usually considered strong enough for use in the creep-limited range.Clear as mud?

If you go by this post then you should avoid using Dual Certified Steel (L) at higher temperatures and should go for the other Dual Certified Steel(H).

See if this is of any help!

Thanks again for the explanation, but it still ist an answer to my question (I believe).
I'm talking specifically about the 0 deg C - 425 deg C (~ 842 F) temperature range, which is below the range mentioned in your last post.
Second, I'm dealing with flanges, not with plates.

See the corresponding ASTM and especially the ASME B16.5 design notes; then you'll understand where my question comes from.

Briefly; 304L flanges may only operate up to 425 deg C (per ASME B16.5).
So, may 304/304L flanges (say 150 lbs) operate up to 538 deg C then?
Why or why not?

The post #4 by JamesKelly mentions Temperature suitability

Almost all "304" plate is dual certified. It may be 0.03 max carbon stuff dual certified 304L/304. This, meanins it has decent corrosion resistance as-welded and the tensile & yield properties of 304, at least near room temperature.1150F is in the creep range, for which you need dual certified 304/304H. This has a minimum of 0.04% carbon for strength, plus I think both grain size and minimum annealing temperatures. It is widely available.Dual certification is the common practice. The mill does not want to melt two or three different chemistries, i.e. 304L, 304 and 304H so they make two different chemistries do the work of these three. It is the magic of precise chemistry control by refining the melt in an Argon-Oxygen Decarburization vessel, where a little nitrogen brings up the yield strength of 304L to the requirements of 304. Great for room temperature but the dual-certified "L"grade is not usually considered strong enough for use in the creep-limited range.Clear as mud?

If you go by this post then you should avoid using Dual Certified Steel (L) at higher temperatures and should go for the other Dual Certified Steel(H).

See if this is of any help!

Thanks again for the explanation, but it still ist an answer to my question (I believe).
I'm talking specifically about the 0 deg C - 425 deg C (~ 842 F) temperature range, which is below the range mentioned in your last post.
Second, I'm dealing with flanges, not with plates.

See the corresponding ASTM and especially the ASME B16.5 design notes; then you'll understand where my question comes from.

Briefly; 304L flanges may only operate up to 425 deg C (per ASME B16.5).
So, may 304/304L flanges (say 150 lbs) operate up to 538 deg C then?
Why or why not?

Bump, anyone?