Examiner

A person who performs specific NDE on equipment but does not evaluate the results of those examinations, unless specifically trained and authorized to do so by the owner or user. The examiner may be required to hold certifications as necessary to satisfy the owner or user requirements.

Erosion

A reduction in material thickness due to mechanical attack from a fluid, expressed in inches or millimeters.

Economizer

A section of the boiler where incoming feedwater temperature is raised by recovery of the heat from flue gases leaving the boiler.

Duct

A conduit for air or flue gas flow.

Downcomer

Boiler tubes or pipes where the fluid flow is away from the steam drum

Damper

A device for introducing a variable resistance for regulating volumetric flow of gas or air.

Butterfly Damper

A single-blade damper pivoted about its center

Bridgewall

A division or gravity wall which separates two adjacent heater zones.

Breeching

The heater section where the flue gases are collected after the last convection coil for transmission
to the stack or the outlet duct work.

Backup layer (Boiler)

Any refractory layer behind the hot face layer

Crossover (Boiler)

The interconnecting piping between any two heater coil sections.

Corrosion Rate

The reduction in the material thickness due to the chemical attack from the process fluid or flue gas or both, expressed in mils per year or millimeters per year.

Corrosion Allowance

The additional metal thickness added to allow for metal loss during the design life of the component.   It is the corrosion rate multiplied by the tube design life, expressed in inches or millimeters.

Corbel

A projection from the refractory surface generally used to prevent flue gas bypassing the convection section tubes.

Convection Section

The portion of the heater in which the heat is transferred to the tubes primarily by convection.

Chelate

An organic compound used in boiler water treatments which bonds with free metals in solution.  Chelates help prevent metals from depositing upon tube surfaces.

Ceramic Fiber

A fibrous refractory insulation composed primarily of silica and alumina (and sometimes zirconia) that can

comes in various forms like blanket, board, module, rigidized blanket, and vacuum-formed shapes.