4.1 The weight per unit area measurement is an indication of the relative cleanliness or dirtiness of the boiler. It is used to determine the effectiveness of the boiler chemical treatment program and to determine the need for chemically cleaning the boiler systems. Allowing the internal deposition to accumulate unchecked will likely lead to boiler tube failures by mechanisms of under deposit corrosion and tube metal overheating.
1.1 These test methods cover the determination of the weight per unit area of waterside deposits on heat-transfer surfaces of steam generator tubes. The following test methods are included:
| Sections |
Test Method A—Mechanical removal by scraper or vibrating tool-removed deposit weight method | 7 to 16 |
Test Method B—Chemical removal by solvent-tube weight loss method | 17 to 27 |
Test Method C—Mechanical removal by glass-bead blasting-tube weight loss method | 28 to 37 |
1.2 Test Method A is a procedure generally applicable to deposits ranging from 1 to 100 g/ft2. The precision was determined in the collaborative study over the range of 16 to 76 g/ft2. This procedure allows the discretionary selection of the area on the tube to be sampled. The removed deposit allows for further chemical analysis.
1.3 Test Method B is a procedure generally applicable to deposits ranging from 1 to 100 g/ft2. The precision was determined in a collaborative study over the range of 28 to 73 g/ft2. The procedure averages out the heavier and lighter deposited areas. The solvent solution produced allows for further chemical analysis.
1.4 Test Method C is a procedure generally applicable to deposits ranging from 1 to 100 g/ft2. The precision was determined in a collaborative study over the range of 17 to 88 g/ft2. The procedure averages out the heavier and lighter deposited areas. The removed deposit does not allow for further chemical analysis.
1.5 These test methods have been generally evaluated on the types of waterside deposits generally found on heat-transfer surfaces of steam generator tubes. It is the user’s responsibility to ensure the validity of these test methods for other types of deposits or high temperature scale.
1.6 These methods are sometimes used for accumulated deposition in rifled steam generator tubes. Experience has shown that there is a sig......
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