Boilers play an integral role in the operation of several plants and process operations, and for this reason, their maintenance is paramount to general efficiency and subsequently the overall bottom line of this plant. But do you understand the scale of havoc that a badly preserved boiler can cause? Keep reading to discover.
Boiler tube (which is also known as “ท่อบอยเลอร์” in the Thai language) failures are the major cause of forced outages in fossil fuel power plants. This statement alone should be reason enough to perform routine thorough inspection, but let us look a bit deeper and find out why exactly this might be the case.
Caustic Attack – This happens when there is excessive deposition on the inner diameter of the tubes. Contact surface area is reduced which causes diminished cooling and localized boiling beneath the deposit. If chemistry upsets happen, and the PH level gets high a caustic condition can happen which corrosively attacks the protective magnetite.
Oxygen Pitting – This happens when excess oxygen is present in the boiler water. Oxygen pitting is most prevalent near the economizer feedwater inlet for operating boilers and contributes to wall loss.
Hydrogen Damage – This is caused by corrosion cells releasing atomic hydrogen, causing decarburization of the tube. This induces intergranular cracking, loss of ductility and may cause a fragile catastrophic rupture. Not all corrosion cells grow into hydrogen damage, however, if rust is present, some will most likely have hydrogen damage also.
NDT or Non-Destructive Testing as it is also known can detect, and prevent these issues from possibly occurring or developing into larger problems. All the issues above lead to failure, even though through utilization of the techniques we are going to summarize, information can enable us to diagnose problems like a cracked feedwater heater (contributes to rust & hydrogen damage, then collapse), in addition to identifying purely the regions of tube damage.