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Creep of 9Cr1Mo

Home Forums Coking Technical Heaters & Furnaces Creep of 9Cr1Mo

This topic contains 2 replies, has 2 voices, and was last updated by  Anonymous 15 years, 4 months ago.

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  • #4240

    Anonymous

    Considering that one has not experienced any flame impingement, if the coker heater is being operated at 650C (skin TI, during EOR), is creep a suspect? what is a typical indication of creep in 9Cr1Mo coker heater tubes? Does it show measurable, significant bulging (increase in OD)? or, the failure happens with insignificant bulging?

  • #7628

    Anonymous

    Just because you don’t have the flame hitting your tubes you still have about 1700 F in the firebox. For what ever reason you start building coke at a spot, you will start heating this area to a point where you will or can start creep. This will start when you heat this area beyond its yield temperature. You should see hotspots in these areas. This does not happen in a short time. It takes heating in these areas some time to damage these tubes.

  • #7581

    Lucas Revellon
    Participant

    How often is recommended to do pigging in the convection section if it is suspected that 9cr 1Mo is creeping up?  Are there any typical schedules for this operation? Maybe every 6 months or is it done based on skin TI temps?
    Thanks.

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