Chloride Stress Corrosion Cracking (CLSCC) in austenitic stainless-steel tray enclosures

Chloride Stress Corrosion Cracking (CLSCC) in austenitic stainless-steel tray enclosures Chloride stress corrosion cracking has been one of the most common reasons why austenitic stainless-steel tray enclosures deteriorate.  The purpose of the austenitic stainless-steel tray enclosure is to contain non-condensable gases, i.e. O2 and CO2, not allowing these gases to corrode the carbon steel pressure boundary.  In summary, the deterioration...

Principle of Operation

Principle of Operation The main principle behind the deaeration process is Henry’s Law.  Henry’s law is a principle in physical chemistry that states that the quantity of dissolved gas in a liquid is directly proportional to the partial pressure above the liquid.  In deaeration, the partial pressure above the water is decreased with the rise in temperature of the water. ...

The Two Main Types of Boiler Deaerators

Tray-type deaerator   A tray-type deaerator typically has a deaeration section mounted above a horizontal feedwater storage vessel. Water enters the deaeration section into a stainless-steel enclosure through stainless steel spray valves mounted to a horizontal header pipe.  During the 1st stage of deaeration, the water is dispersed in a fine film or droplets above a section of trays.  The water is...

Why are Deaerators ASME Code Stamped?

ASME Boiler and Pressure Vessel Code was first issued over 100 years ago, and has since evolved into a leading standard internationally.  The back cover of the Code book contains a statement regarding ASME’s commitment to public safety.  Deaerators under pressure contain large quantities of stored energy which can be dangerous.  The ASME Code contains rules and requirements for design, manufacture, and...

Deaerator Inspection and Maintenance

While some plants are diligent about regular inspections, others are not.  Regular deaerator inspection and maintenance is critical because of the classic phrase, “a stitch in time”.  Many failures or unplanned shutdowns can be avoided with planned inspections. Cracks in welds – minor cracks can be discovered and repaired before they become a major problem. Erosion or Flow Accelerated Corrosion (FAC) – usually...

How to Measure the Efficiency of a Deaerator

A deaerator is a specialized piece of equipment used with a boiler.  It's purpose is to dissolve oxygen through a mechanical process to reduce the need for water treatment with chemicals.  It effectively removes other gases as well, which protects the boiler from being pitted or corroded so it has a longer lifespan. Measuring the technical efficiency of a deaerator...