304L performance at High Temperature
304L performance at High Temperature
(OP)
We have had an emergency shutdown on our plant, and need to get in a new piece of pipework quickly to replace an economiser that will be sent for repair. The pipework is 12" nb, and is for flue gases at low pressure <<1 bar, but high design temperature (810°C, 1490°F). I believe that the ideal pipework is 304H, but this is long delivery. Will 304L be OK in the short term (Say 2-3 months running)? What will be the failure mode, i.e. could the pipe potentially rupture catastrophically, or is it more likely to lead to a gradual leakage at the flanges?





RE: 304L performance at High Temperature
You MIGHT have a small difference in strength, but corrosion-wise they should perform the same at those high temps.
RE: 304L performance at High Temperature
I disagree with Metalguy (Materials)304L @850F "NO"
alway check ASME SECTION II, MATERIAL "PART D"
RE: ASME SECTION II, MATERIAL "PART D" 304H @850F, SH=11,000 (OK); and 304L @850F "NO"
Leonard@thill.biz
www.thill.biz
RE: 304L performance at High Temperature
At those very high temps. and conditions 304/304L does very well. We don't even know if he needs a code material or not.
RE: 304L performance at High Temperature
PER B31.3 (FOR PIPING) (ASME SEC II is for pressure vessels) 304L is OK up to 1500Deg F but the allowable stress drops off to 900PSI. 304H is also good for 1500Deg F and the stress drops off to 1400PSI.
304H is the best but 304L should perform satisfactorily, especially since the pressure is so low.
RE: 304L performance at High Temperature
However, there are other SS alloys more suitable for high temperature.
Carpenter Stainless Steel. Selection. Alloy Data. Fabrication shows that the safe scaling temperature for 304 SS is 1600oF (871oC) whereas Types 446 and 7-Mo have a safe scaling temperature of 1900oF (1038oC).
RE: 304L performance at High Temperature
I agree with DLANDISSR (Mechanical)& kenvlach (Materials), as the "AI/engineer" I would use 304H or better.
RE: 304L performance at High Temperature
In terms of corrosion, this is not really an issue - carbon steel would be acceptable, but am advised it will not take this kind of temperature. The rest of the existing pipework downstream of the economiser is 321 SS.
In terms of what caused the economiser to fail - that almost certainly was corrosion, but due to the chemical (High strength, high temperature caustic) on the other side of the economiser.