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FAILURE OF THERMAL OXIDIZER PREHEATER TUBES

  • 1.  FAILURE OF THERMAL OXIDIZER PREHEATER TUBES

    Posted 8 days ago
    Edited by Ahmed Reyad 8 days ago
    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...)

    ------------------------------
    Ahmed Reyad--


  • 2.  RE: FAILURE OF THERMAL OXIDIZER PREHEATER TUBES

    Posted 8 days ago
    Good morning

    Are you in a position to provide details on tube side and shell side temperatures ?

    How old are the tubes ?

    Seems like some tubes did experience temperature-pressure combination to put the applied stress above the yield stress.

    Need some more details to help you out.

    ------------------------------
    Chirayu Garud
    Sr.Integrity Specialist
    BP
    Chicago IL
    3092293677
    ------------------------------



  • 3.  RE: FAILURE OF THERMAL OXIDIZER PREHEATER TUBES

    Posted 8 days ago
    Edited by Ahmed Reyad 8 days ago
    It is 3" and 3mm thickness, one piece (no welding)
    Failure after 2:3 y in service
    flue gas temperature between 700-800 C and acid gas is ambient

    ------------------------------
    Ahmed Reyad

    ------------------------------



  • 4.  RE: FAILURE OF THERMAL OXIDIZER PREHEATER TUBES

    Posted 7 days ago
    Dear Mr Ahmed,

    For Flue gas Environment- Hastelloy C276 Material of construction is widely recommended to withstand the temperature and corrosion due to flue gas.

    Thank you!

    Regards,

    Hitesh M.Mehta
    Shripal Metal Ltd.
    Mumbai-India






  • 5.  RE: FAILURE OF THERMAL OXIDIZER PREHEATER TUBES

    Posted 4 days ago
    Dear 
    The carbon % of the alloy 253 MA is relatively high which make this alloy susceptible to sensitization (formation of chromium carbide at higher temperature) this phenomenon had a detrimental impact on:

     -Corrosion resistance (depleted chromium zone is more prone to corrosion): poor corrosion resistance

    -Yield strength: Lower yielding strength

    This combination of those issues made this alloy more susceptible to creep failure.

    So most probably this is a creep failure

    Thanks

    ------------------------------
    Elhazel Aymen
    GCT
    Fertilizer
    ------------------------------



  • 6.  RE: FAILURE OF THERMAL OXIDIZER PREHEATER TUBES

    Posted 2 days ago
    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.

    ------------------------------
    Rodrigo Faveret Signorelli
    Technical Manager
    Outokumpu, Inc.
    Sao Paulo
    5511986970164
    ------------------------------