25 May 2005
Table 3-20. Treatment Guidelines for Very-High-Pressure Steam
Boiler Water Treatment Control
Maximum of 100, per ASME.
Maintain pH, per ASME guidelines, using
General corrosion control
phosphate, or with all volatile treatment.
Volatile hydrazine substitutes: hydroxylamine,
Pitting corrosion control
hydroquinone, carbohydrazide, hydrazine
sulfate, tannin derivatives, or erythorbic acid.
Maintain pH of 7.5-9.3 using specialty volatile
Condensate corrosion control
oxygen scavengers listed for pitting control
External treatment to remove scaling agents.
Example: RO with demineralization
External treatment to remove alkalinity and
Carryover control due to foaming
other minerals. Example: RO with
Boiler Operator Duties. Operators should keep feedwater quality, COC,
and treatment levels within program control limits at all times. Operators must perform
recordkeeping and assess trends in the results of system performance tests routinely
(see paragraph 1-1.8). When changes in feedwater quality, TDS, or chemical treatment
levels occur, the operator must investigate and resolve the reasons for these changes.
Boiler operators need to understand their equipment and how it operates. Does it
operate seasonally? Does it operate intermittently? Does the amount of condensate
return vary? These conditions may require adjustments in chemical treatment.
Paragraphs 3-4 and 3-5 present some common problems.
Chemical Requirements for Boiler Start-up. Start-up of a new or
repaired boiler requires special water treatment procedures. The start-up of a boiler
after a wet or dry layup period also requires special water treatment procedures.
Common Problems During Start-up of New Boilers. A common
problem that can occur during start-up of new boilers is corrosion of the boiler tubes due
to improper initial conditioning of the water and boiler metal. Carryover of boiler water
due to improper start-up can also occur, particularly with new boilers.