ASME TDP-1:1998 pdf download RECOPi1MENDED PRACTIIES FOR THE PREVENTION OF WATER DAMAEE TO STEAM TURBINES USED FOR ELECTRI I : POWER GENERATION
1 SCOPE
These recommended practices are concerned primar- ily with the prevention of water damage to steam turbines used for fossil fuel fired electric power genera- tion. The practices cover design, operation, inspection, testing, and maintenance of those aspects of the follow- ing power plant systems and equipment concerned with the prevention of the induction of water into steam turbines and associated systems and equipment:
main steam system, piping, and drains;
reheat steam systems, piping, and drains;
reheat attemperating system;
turbine extraction systems, piping, and drains;
feedwater heaters, piping, and drains;
turbine drain system;
turbine steam seal system, piping, and drains;
main steam attemperator sprays;
start-up systems;
condenser steam and water dumps.
Any connection to the turbine is a potential source of water either by induction from external equipment or by accumulation of condensed steam. The sources treated specifically are those that have been found to be most frequently involved. 2 CRITERIA 2.1 Recommendations Design, control, and operation of all systems that have a potential for allowing water to enter the turbine should prevent any unusual accumulations. However, since malfunctions do occur, the recommendations for preventing turbine damage due to water induction in- clude one or more of the following where appropriate:
(a) detection of the presence of water either in the turbine or, preferably, external to the turbine before the water has caused damage;
(b) isolation of the water by manual or, preferably, automatic means after it has been detected;
(c) disposal of the water by either manual or, prefera- bly, automatic means after it has been detected.
2.2 Failure Where experience has shown a source of water is particularly hazardous, no single failure of equipment should result in water entering the turbine. The failure mode of the various devices used to prevent water induction should be considered so that a single failure of the signals (loss of air or electrical signal) will not cause water to enter the turbine.
3 DESIGN RECOMMENDATIONS This Section outlines specific recommendations for the design of the systems listed. These recommendations are intended to represent a conservative design for protection from water induction. There is no intention to supersede any existing codes or governmental regula- tions.
3.1 Steam Generators
3.1.1 It is the responsibility of the plant designers to review and understand the design features of the steam generator and of the user to adhere to the operating procedures of the steam generator manufacturer as a precaution against water induction. The majority of the incidents of turbine water damage caused by water entering the turbine from the steam system have occurred during start-up or shutdown of a unit. The steam generator manufacturer’s design and operating recommendations should include the required protection to prevent the induction of water into the main steam piping. Such areas as superheater attemperators, boiler start-up systems, high drum levels, and undrained super- heaters are some potential sources of water.