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  • in reply to: Experience of blade failure #2387
    powerplantdocs
    Participant

    I have no experience of blades causing damage to tube bundles but I would not rule it out if your ACC is an induced draft W style. Potential damage to the ACC structure should not be a concern. The Oh Shit! vibration trip switch should safely shutdown the motor within a few seconds of the fan blade detachment. Unlike most rotating equipment e.g. pumps and turbines the protective vibration sensors or switches typically aren’t preemptive but more so installed to shutdown upon or ater fan blade failure.

    in reply to: Experience of blade failure #2385
    powerplantdocs
    Participant

    Impractical? Please do tell.

    in reply to: Experience of blade failure #2381
    powerplantdocs
    Participant

    Marcel,

    If you have cracks in the fan blades that are deeper than 1/16″ then you should consider not operating the fans and plan on repairing or replacing them depending upon the extent of the cracks and where they are located. It is good practice to have one set of replacement fan blades at a minimum this way you can shutdown and replace the affected blades and then take time to properly inspect and repair the cracked blades.

    If the cracking is minimal to where it just catches your finger tip and no fiberglass is exposed the fan blade may be a candidate for cleaning, prepping and recoating in-place.

    As for tripping on vibration prior to breaking? Most times no. The failure is more often than not immediate and may result in additional damage to adjacent blades.

    If you have additional questions, comments or concerns please do not hesitate to contact me a mcyr@powerplantdocs.com 202-486-5694. I have over 12 years of experience as a Commissioning Manager with SPG (SPX) Dry Cooling and B&W SPIG Dry Cooling and am presently a consultant to the Power Industry specializing in Air Cooled Condensers and Cooling Towers.

    in reply to: ACC Fan Blade cracks #2256
    powerplantdocs
    Participant

    Joshua,

    At your earliest opportunity check the torque of these bolts. Have experienced loosening of the bolted joint due to compression of the fiberglass over time. The plates are installed to increase the clamping surface area and to minimize compression of the fiberglass material. Last project where I witnessed issues with Cofimco blades the bolts started to snap, fiberglass cracked as you are experiencing, bolts fell out, etc. Had to replace/rebuild the affected fan blades and retorque others. Cofimco increased the bolt torque value for this particular unit.

    in reply to: Steam Duct Support Failure #2255
    powerplantdocs
    Participant

    Have witnessed this occurring at a facility in Nevada. If the bolts for these stiffeners are shearing then I would advise that you look at the Condensate headers for freedom of movement. There is only one fixed point for each CCM and SDM provided to limit the direction of thermal growth. If the CCM and SDM are not allowed to “grow” and slide in the intended direction then stresses may be applied elsewhere. Drop me a line. Marty mcyr@powerplantdocs.com

    in reply to: ACC Fan Blade cracks #2254
    powerplantdocs
    Participant

    Joshua,

    As a former Commissioning Manager for SPG (SPX) Dry Cooling and B&W SPIG Dry Cooling for over 10 years I have had experience with what you are currently experiencing. If you want you can e-mail me at mcyr@powerplantdocs.com or mcyr01@outlook.com and I can provide you with some info and possibly direct you to the folks who can help you.

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