A procedure for removing tube samples from a boiler in order to assess internal surface conditions. Involving the removal of deposition from a measured area of the surface of a tube so the weight of deposit per unit area of tube surface can be calculated.Prior to removing a failed tube, mark and photo document the tube gas flow direction, fluid flow direction, row number, elevation, boiler section, etc.

The visual condition of nearby tubes and the proximity of the damaged tubing to attachments, soot blowers, etc. should also be documented. Samples should be a minimum of 18” long and cuts should be made well away of any visible damage. Dry cuts should be made with an electric or air powered reciprocating saw or grinder with a thin cut-off wheel to obtain high quality cuts. Tube ends should be sealed with tape to prevent contamination or loss of deposits or scale. The tube samples should be carefully packed to prevent damage during shipment.

The following information should be provided with the Boiler tube samples

• *  Boiler controlling pressure, temperature, steaming rate, and unit MW
• *  Boiler tube mapping shows the location of each sample.
• *  Particular  tube material, dimensions, etc.
• *  Functioning hours since commercial operation date or tube replacement
• *  History of the boiler tube failure
• *  Maintenance of boiler records (i.e., replacements or modifications) for the boiler section of concern
• *  Boiler water chemistry (typical chemistry and frequency, extent, and duration of excursions)
• *  Short-term, Long-term - Layup process