National Board Consultant
Summary: The following article is a part of National Board Classic Series and it was published in the National Board BULLETIN. (3 printed pages)
"Why?" is the question that is always on the mind of the curious boiler inspector.
The inspector, whether from the jurisdiction, insurance company or the operator/maintainer, must always ask this question. The inspector's job is not finished when corrective action is recommended to correct an obvious problem discovered during an inspection; there is more. The inspector must ask, "Why did this happen?"
Review the following hypothetical situation as an example.
An inspector discovers cracks in the fireside of a mud-leg in a firebox-type steam boiler and recommends a repair by welding. In this case, if the question, "Why did the plate crack?" is not asked, only the symptom is corrected and the cause of the problem is not detected. If the question is asked, further investigation may reveal that the mud-legs are packed with scale, insulating the plate from boiler water. Of course it would be required that the boiler be cleaned of scale before the weld repairs are made.
If a second question, "Why is there scale?" is not addressed, then another symptom would be corrected without affecting the root of the problem. When the cause of the scaling is investigated, it would most likely be discovered that the boiler is using excessive make-up water. Again, why? After pressing further, the investigation reveals that the condensate return pipe is leaking. It would be recommended that the leaking pipe be replaced.
The investigation continues, only to uncover that the pipe leaked because of internal corrosion. It is now recommended that the services of a water treatment specialist be acquired. The specialist determines the boiler water requires treatment not only for preventing scale in the boiler, but also treatment of the condensate and pre-boilers systems to inhibit corrosion.
The inspector recommends that the boiler water treatment program be closely monitored and adjusted as necessary.
If the inspector had stopped asking, "Why?" at any point during the investigation, only the symptoms would have been corrected and the problems would be recurring.
Inspections routinely evolve into investigations with symptoms of a problem providing the clues to the inspector. Only by asking, "Why?" at each step of the investigation will the inspector identify the root cause of the problem and be able to recommend the proper and complete corrective action.
Editor's note: Some ASME Boiler and Pressure Vessel Code requirements may have changed because of advances in material technology and/or actual experience. The reader is cautioned to refer to the latest edition of the ASME Boiler and Pressure Vessel Code for current requirements.