Selection of Papers by L.D. Porta Volume 4 – Special Edition – Locomotive Boiler Water Treatment, Feedwater Heating and Boiler Water Behaviour (Hard Cover version)

What counts is what one has in the boiler, not what one feeds into it.” 

Ing. L.D.Porta’s simple statement outlines, in just a few words, what became his approach to boiler water treatment.  It seems at odds with accepted thinking on the topic, what did he mean by this?  Very simply, if the boiler water chemistry is within a defined range the nature of the feedwater is of no concern.

It has been known since the 1970s with certainty, but for a few decades previously less clearly, that with a certain boiler water chemistry it is possible, in a practical sense, to prevent scale formation, corrosion and caustic embrittlement1.  The use of Porta’s system also ensures fully mobile, non-adherent sludge formation and the production of technically pure steam, foaming and boiler water swelling are controlled.  

The boiler water chemistry is controlled through the addition of chemicals dosed at a defined rate, whilst the locomotive is in service, regardless of feedwater conditions.  Naturally, the testing of boiler water samples needs to be undertaken to ensure success.  The test results indicate if extra alkalinity needs to be added or if a boiler blowdown is required.  Boiler water alkalinity and dissolved solids concentration are the two factors that are controllable conditions.

The implications of this are clear. Feedwater constantly varies at and between watering points.  There is nothing which can be done to change this unless a form of external treatment is applied, which the above suggests is not necessary.  Therefore why be concerned by feedwater variation?  Trying to accommodate any variations through adapting treatment dosing is always going to be, at best, difficult and inadequate.  History has shown this to be the case, but it remains a common approach.

This volume contains much information supporting Porta’s statement and approach.