Hello Ahmed,
253MA is an ideal alloy for high temperature specially when it comes to creep, given its composition including micro-alloying. Similar to 310 stainless, it has nearly twice the creep strength at moderately high temperatures.
At the temperatures described, 253MA is perhaps not the best choice.
I assume you don´t have the actual tube metal temperature, but you did mention the failure happened in the colder region of the equipment. Based on this, it´s more likely that the root causes are formation of secondary phases/embrittlement than creep itself. Creep is not known to be a failure mode at such low temperatures.
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Rodrigo Faveret Signorelli
Technical Manager
Outokumpu, Inc.
Sao Paulo
5511986970164
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Original Message:
Sent: 09-09-2021 09:28 AM
From: Ahmed Reyad
Subject: FAILURE OF THERMAL OXIDIZER PREHEATER TUBES
Hi All,
we have a failure in some of the tubes of the thermal oxidizer preheater, I am looking for any experience with similar failures/root cause
for our case, the below summarizes the case:
- the tubes are heated externally by the flue gas from a thermal oxidizer and then acid gas gets introduced inside the tubes
- 4 tubes out of 24 tubes (all in the inlet/colder side of the U-Bend tubes) in the Acid Gas inlet side were found with deformation, ruptures, and cracking.
- longer tubes showed indication of deformation at the contact point with the tube guide
- Material analysis showed indications of thermal fatigue (material is 253MA-Austenitic SS)
any experience with similar failures and the root cause is highly appreciated, mainly I am trying to understand why specific tubes would fail out of the 24 tubes if we consider the bundle internally and externally are exposed to the same conditions (temperature, flow rate...)
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Ahmed Reyad--