Significance and Use
5.1 The transport of any suspended solids or corrosion products from the preboiler cycle has been shown to be detrimental to all types of steam generating equipment. Corrosion product transport as low as 10 ppb can have significant impact on steam generators performance.
5.2 Deposited corrosion products on pressurized water reactor (PWR) steam generator tubes can reduce heat transfer, and, if the deposit is sufficiently thick, can provide a local area for impurities in the bulk water to concentrate, resulting in a corrosive environment. In boiling water reactor (BWR) plants, the transport of corrosion products can cause fuel failure, out of core radiation problems from activation reactions, and other material related problems.
5.3 In fossil plants, the transport of corrosion products can reduce heat transfer in the boilers leading to tube failures from overheating. The removal of these corrosion products by chemical cleaning is expensive and potentially harmful to the boiler tubes.
5.4 Normally, grab samples are not sensitive enough to detect changes in the level of corrosion product transport. Also, system transients may be missed by only taking grab samples. An integrated sample over time will increase the sensitivity for detecting the corrosion products and provide a better understanding of the total corrosion product transport to steam generators.
1.1 This practice is applicable for sampling condensed steam or water, such as boiler feedwater, for the collection of suspended solids and (optional) ionic solids using a 0.45-μm membrane filter (suspended solids) and ion exchange media (ionic solids). As the major suspended component found in most boiler feedwaters is some form of corrosion product from the preboiler system, the device used for this practice is commonly called a corrosion product sampler.
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.