Slagging may cause rapid deterioration of boiler hardware such as tube hangers and spacers. The general effect of slagging is to decrease the thickness of the refractory and thereby reduce its insulation properties. Metal oxides found in fuel oil are fluxing agents. Fluxing occurs and produces a slag that may be fluid at boiler operating conditions. Leakage of hot boiler gases through joints when the edges have crumbled or when the tile or insulating concrete has fallen out may expose the supporting steel to high metal temperatures, rapid oxidation, and corrosion.įly-ash corrosion may occur when fly-ash and refractory are in contact. Refractory is inspected for breakage, slagging, crumbling, spalling, and open joints. Refractory and insulation are inspected to determine if there is any deterioration. Supports are inspected for corrosion and damage and to make sure they are functioning properly. Tubes and drums are inspected at support points to see if there is any binding or wear. Tube samples may be taken for inspection of the metal deterioration and measurement of deposits. The tube and drum thickness are measured ultrasonically to determine a corrosion rate. Drums and shells are inspected externally for excessive fire scale, cracking of joints and any indication of leakage (deposits) at the tube to drum connections. Sagging roof tubes are especially susceptible to overheating. Tubes are inspected externally for excessive fire scale (fireside scale), deformation (bulging) or sagging that may indicate overheating. Inspection intervals are based on service and experience.īoiler Inspection is not an exact science and requires the use of judgement and experience. There is no mandatory inspection requirements for heaters. ASME Code Standards require boiler inspection to be done at least every year. A comprehensive equipment history must be maintained that includes conditions found during inspection and testing, maintenance work done, changes made, and date of each. Pressure vessels and Boiler Inspection are done to determine the amount of maintenance required to have equipment operate properly until the next turnaround.

Boiler inspection requirements by state