Failure of an HK40 heater support system

 

HK40 tube support

Item:

  • HK40 support system in a catalytic reformer heater at a UK refinery

Problem:

  • Two of the eight high temperature (980°C) radiant section supports had failed, leaving the remaining six to support the full load
  • Supply of replacement HK40 material has a lead time of two months

Objective:

  • Fitness for service and remaining life assessment to consider whether the surviving supports could sustain the load until a convenient time for replacement

Approach:

  • Removal of failed supports from operating heater
  • Metallographic examination revealed failure to be by creep
  • Creep life assessment predicted that the remaining life of the current supports, subjected to the higher support loads, to be a matter of days, or even hours

Solution:

  • 24 hour monitoring of remaining supports instigated
  • Plant immediately put into condition for most economic safe shutdown
  • An alternative material to HK40 proposed for support replacement and new supports constructed in days

Outcome:

  • Failure of third support two days later
  • Heater immediately shut down safely

Benefits:

  • Catastrophic failure of heater, with associated consequential loss, avoided
  • Alternative solution to existing long lead time material procurement
  • Safe shutdown and monitoring processes identified and implemented

Plant Integrity