Contents-Boiler Design and Material-Article, Essays (high school) of Boiler Design and Material

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ARTICLE NB-7000 NB-7100 General Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 251 NB-7110 Scope. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 251 NB-7111 Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 251 NB-7120 Integrated Overpressure Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 251 NB-7130 Verification of the Operation of Reclosing Pressure Relief Devices. . . . . . . . . . . . . . . 251 NB-7131 Construction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 251 NB-7140 Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 252 NB-7141 Pressure Relief Devices. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 252 NB-7142 Stop Valves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 252 NB-7143 Draining of Pressure Relief Devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 252 NB-7150 Acceptable Pressure Relief Devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253 NB-7151 Pressure Relief Valves. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253 NB-7152 Nonreclosing Pressure Relief Devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253 NB-7160 Unacceptable Pressure Relief Devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253 NB-7161 Deadweight Pressure Relief Valves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253 NB-7170 Permitted Use of Pressure Relief Devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253 NB-7171 Safety Valves. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253 NB-7172 Safety Relief Valves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253 NB-7173 Relief Valves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253 NB-7174 Pilot Operated Pressure Relief Valves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253 NB-7175 Power Actuated Pressure Relief Valves. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253 NB-7176 Safety Valves With Auxiliary Actuating Devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253 NB-7177 Pilot Operated Pressure Relief Valves With Auxiliary Actuating Devices . . . . . . . . . 253 NB-7178 Nonreclosing Devices. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253 NB-7200 Overpressure Protection Report . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 254 NB-7210 Responsibility for Report . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 254 NB-7220 Content of Report. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 254 NB-7230 Certification of Report. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 254 NB-7240 Review of Report After Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 254 NB-7250 Filing of Report . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 254 NB-7300 Relieving Capacity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 255 NB-7310 Expected System Pressure Transient Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 255 NB-7311 Relieving Capacity of Pressure Relief Devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 255 NB-7312 Relieving Capacity of Pressure Relief Devices Used With Pressure Reducing Devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 255 NB-7313 Required Number and Capacity of Pressure Relief Devices. . . . . . . . . . . . . . . . . . . . . . 255 NB-7314 Required Number and Capacity of Pressure Relief Devices for Isolatable Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 255 NB-7320 Unexpected System Excess Pressure Transient Conditions . . . . . . . . . . . . . . . . . . . . . . . 255 247 docsity.com NB-7321 Relieving Capacity of Pressure Relief Devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 255 NB-7400 Set Pressures of Pressure Relief Devices. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 255 NB-7410 Set Pressure Limitations for Expected System Pressure Transient Conditions . . . . . . 255 NB-7420 Set Pressure Limitation for Unexpected System Excess Pressure Transient Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 256 NB-7500 Operating and Design Requirements for Pressure Relief Valves . . . . . . . . . . . . . . 256 NB-7510 Safety, Safety Relief, and Relief Valves. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 256 NB-7511 General Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 256 NB-7511.1 Spring-Loaded Valves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 256 NB-7511.2 Balanced Valves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 256 NB-7511.3 Antisimmer Type Valves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 256 NB-7512 Safety Valve Operating Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 256 NB-7512.1 Antichattering and Lift Requirements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 256 NB-7512.2 Set Pressure Tolerance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 256 NB-7512.3 Blowdown. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 256 NB-7513 Safety Relief and Relief Valve Operating Requirements . . . . . . . . . . . . . . . . . . . . . . . . . 256 NB-7513.1 Set Pressure Tolerance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 256 NB-7513.2 Blowdown. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 257 NB-7514 Credited Relieving Capacity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 257 NB-7515 Sealing of Adjustments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 257 NB-7520 Pilot Operated Pressure Relief Valves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 257 NB-7521 General Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 257 NB-7522 Operating Requirements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 257 NB-7522.1 Actuation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 257 NB-7522.2 Response Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 257 NB-7522.3 Main Valve Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 257 NB-7522.4 Sensing Mechanism Integrity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 257 NB-7522.5 Set Pressure Tolerance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 257 NB-7522.6 Blowdown. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 257 NB-7523 Credited Relieving Capacity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 258 NB-7524 Sealing of Adjustments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 258 NB-7530 Power Actuated Pressure Relief Valves. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 258 NB-7531 General Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 258 NB-7532 Operating Requirements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 258 NB-7532.1 Actuation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 258 NB-7532.2 Response Times . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 258 NB-7532.3 Main Valve Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 258 NB-7532.4 Sensors, Controls, and External Energy Sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 258 NB-7533 Certified Relieving Capacity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 258 NB-7534 Credited Relieving Capacity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 258 NB-7534.1 Expected System Pressure Transient Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 258 NB-7534.2 Unexpected System Excess Pressure Transient Conditions . . . . . . . . . . . . . . . . . . . . . . . 258 NB-7535 Sealing of Adjustments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 259 NB-7540 Safety Valves and Pilot Operated Pressure Relief Valves With Auxiliary Actuating Devices. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 259 NB-7541 Construction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 259 NB-7542 Expected System Pressure Transient Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 259 NB-7543 Unexpected System Excess Pressure Transient Conditions . . . . . . . . . . . . . . . . . . . . . . . 259 NB-7544 Auxiliary Device Sensors and Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 259 248 docsity.com NB-7250 NB-7000 — OVERPRESSURE PROTECTION NB-7410 Inspector signing the Owner’s Data Report. The report shall be made available to the Authorized Inspector and regulatory and enforcement authorities having juris- diction at the nuclear plant site. NB-7300 RELIEVING CAPACITY NB-7310 EXPECTED SYSTEM PRESSURE TRANSIENT CONDITIONS12 NB-7311 Relieving Capacity of Pressure Relief Devices (a) The total relieving capacity of the pressure relief devices (certified in accordance with NB-7700 intended for overpressure protection within the scope of this Subsection and credited in conformance with NB-7500 or NB-7600) shall take into account any losses due to flow through piping and other components. (b) The total relieving capacity shall be sufficient to prevent a rise in pressure of more than 10% above the Design Pressure of any component within the pressure-retaining boundary of the protected system under any expected system pressure transient conditions as summarized in the Overpressure Protection Report (NB-7200). NB-7312 Relieving Capacity of Pressure Relief Devices Used With Pressure-Reducing Devices When using pressure-reducing devices, the combined relieving capacity of the pressure relief devices shall be sufficient to meet the requirements of NB-7311, when: (a) pressure-reducing devices and their bypass valves are fully open; and (b) all discharge paths are blocked on the low pres- sure side of the pressure-reducing device. NB-7313 Required Number and Capacity of Pressure Relief Devices The required relieving capacity for overpressure pro- tection of a system shall be provided by the use of at least two pressure relief devices. In each such group of pressure relief devices when more than one device is used, no device shall have a capacity less than 50% of the device with the largest capacity. 12 Expected system pressure transient conditions are those associated with normal system transient operation, such as loss of feedwater or loss of load. 255 NB-7314 Required Number and Capacity of Pressure Relief Devices for Isolatable Components The required relieving capacity of an isolatable com- ponent shall be provided by at least one pressure relief device meeting the requirements of NB-7500 or NB-7600. NB-7320 UNEXPECTED SYSTEM EXCESS PRESSURE TRANSIENT CONDITIONS13 NB-7321 Relieving Capacity of Pressure Relief Devices (a) The total relieving capacity of the pressure relief devices (certified in accordance with NB-7700 intended for overpressure protection within the scope of this Subsection and credited in conformance with NB-7500 or NB-7600) shall take into account any losses due to flow through piping and other components. (b) The total relieving capacity shall be sufficient to limit the maximum system pressure such that the requirements of (c) are satisfied for each of the compo- nents of the system for which overpressure protection is provided, under each of the unexpected system excess pressure transient conditions specified in the Overpressure Protection Report. (c) The system overpressure established for setting the required total relieving capacity of (b) shall be such that the calculated stress intensity and other design limitations for Service Limit C specified in NB-3000 are not exceeded for each of the components in the protected system. NB-7400 SET PRESSURES OF PRESSURE RELIEF DEVICES NB-7410 SET PRESSURE LIMITATIONS FOR EXPECTED SYSTEM PRESSURE TRANSIENT CONDITIONS The stamped set pressure of at least one of the pressure relief devices connected to the system shall not be greater than the Design Pressure of any compo- nent within the pressure-retaining boundary of the pro- tected system. Additional pressure relief devices may 13 Unexpected system excess pressure transient conditions are those associated with unusual or abnormal system transients, but still considered to be within the design basis, such as loss of load with failure of reactor scram. docsity.com NB-7410 1998 SECTION III, DIVISION 1 — NB NB-7513.1 have higher stamped set pressures, but in no case shall these set pressures be such that the total system pressure exceeds the system limitations specified in NB-7310. NB-7420 SET PRESSURE LIMITATION FOR UNEXPECTED SYSTEM EXCESS PRESSURE TRANSIENT CONDITIONS The establishment of the stamped set pressure shall take into account the requirements of NB-7320. NB-7500 OPERATING AND DESIGN REQUIREMENTS FOR PRESSURE RELIEF VALVES NB-7510 SAFETY, SAFETY RELIEF, AND RELIEF VALVES NB-7511 General Requirements NB-7511.1 Spring-Loaded Valves. Valves shall open automatically by direct action of the fluid pressure as a result of forces acting against a spring. NB-7511.2 Balanced Valves (a) Balanced valves, whose operation is independent of back pressure, may be used if means are provided to verify the operability of the balancing device. (b) Balanced safety valves for steam service shall additionally have a redundant back pressure balancing device. NB-7511.3 Antisimmer Type Valves. Valves which are fitted with antisimmer devices that serve to raise the set pressure of the valve during normal operation of the system may be used, provided: (a) the design is such that the valve opens automati- cally and discharges its certified capacity at 110% of the system design pressure in the event any item of the auxiliary loading device should fail; (b) the operating signal and energy source provisions are such that the valve reverts to its normal set pressure in the event of any failure of signal or loss of energy source; (c) the auxiliary loading force imposed on such valves does not raise the set pressure of the valve by more than 10%; (d) the auxiliary loading force which augments the force exerted by the valve spring is automatically unloaded at a pressure not greater than the set pressure of the valve. 256 NB-7512 Safety Valve Operating Requirements NB-7512.1 Antichattering and Lift Requirements. Safety valves shall be constructed to operate without chattering and to attain rated lift at a pressure which does not exceed the set pressure by more than 3% or 2 psi (13.8 kPa), whichever is greater. NB-7512.2 Set Pressure Tolerance (a) The set pressure tolerance plus or minus shall not exceed the following: 2 psi (13.8 kPa) for pressures up to and including 70 psi (483 kPa), 3% for pressures from 70 psi (483 kPa) to 300 psi (2070 kPa), 10 psi (69 kPa) for pressures over 300 psi (2070 kPa) to 1000 psi (6900 kPa), and 1% for pressures over 1000 psi (6900 kPa). The set pressure tolerance shall apply unless a greater tolerance is established as permissible in the Overpressure Protection Report (NB-7200) and in the safety valve Design Specification (NCA-3250). (b) Conformance with the requirements of (a) shall be established for each production valve by test. Steam valves shall be tested on steam. NB-7512.3 Blowdown. Safety valves shall be ad- justed to close after blowing down to a pressure not lower than 95% of the set pressure unless a different percentage is specified in the safety valve Design Specification (NCA-3250) and the basis for the setting is covered in the Overpressure Protection Report (NB- 7200). The adjustment shall be determined by test or by proration from the Certificate Holder’s blowdown test data. NB-7513 Safety Relief and Relief Valve Operating Requirements Safety relief and relief valves shall be constructed to attain rated lift at a pressure which does not exceed the set pressure by more than 10% or 3 psi (20.6 kPa), whichever is greater. NB-7513.1 Set Pressure Tolerance (a) The set pressure tolerance plus or minus from the set pressure of safety relief and relief valves shall not exceed 2 psi (13.8 kPa) for pressures up to and including 70 psi (483 kPa) and 3% for pressure above 70 psi (483 kPa). The set pressure tolerance shall apply unless a greater tolerance is established as permissible in the Overpressure Protection Report (NB-7200) and in the valve Design Specification (NCA-3250). (b) Conformance with the requirements of (a) shall be established for each production valve by test. Steam valves shall be tested on steam, air or gas valves on air or gas, and liquid valves on liquid. docsity.com NB-7513.2 NB-7000 — OVERPRESSURE PROTECTION NB-7522.6 NB-7513.2 Blowdown. Safety relief and relief valves shall be adjusted to close after blowing down to a pressure not lower than that specified in the valve Design Specification (NCA-3250), and the basis for the setting shall be covered in the Overpressure Protection Report (NB-7200). The adjustment shall be determined by test or by proration from the Certificate Holder’s blowdown test data. NB-7514 Credited Relieving Capacity The credited relieving capacity of safety, safety relief, and relief valves shall be based on the certified relieving capacity. In addition, the capacity can be prorated as in NB-7700. NB-7515 Sealing of Adjustments Means shall be provided in the design of all valves for sealing all adjustments or access to adjustments which can be made without disassembly of the valve. For a pilot operated pressure relief valve, an additional seal shall be provided to seal the pilot and main valve together. Seals shall be installed by the Certificate Holder at the time of initial adjustment. Seals shall be installed in a manner to prevent changing the adjustment or disassembly of the valve without breaking the seal. The seal shall serve as a means of identifying the Certificate Holder making the initial adjustment. NB-7520 PILOT OPERATED PRESSURE RELIEF VALVES NB-7521 General Requirements Pilot operated pressure relief valves shall operate independently of any external energy source. NB-7522 Operating Requirements NB-7522.1 Actuation. The pilot control device shall be actuated directly by the fluid pressure of the protected system. NB-7522.2 Response Time. The Overpressure Pro- tection Report (NB-7200) shall include the effects of divergence between opening (set) and closing (blow- down) pressures of the pilot valve and the pressures at which the main valve attains rated lift and closes. These divergences are caused by the inherent time delay (e.g., response time) between the operation of the pilot and the main valve, and the rate of the system 257 pressure change. The limits for response time shall be specified in the valve Design Specification (NCA-3250). NB-7522.3 Main Valve Operation. The main valve shall operate in direct response to the pilot control device. The valve shall be constructed to attain rated lift under stable conditions at pressures which do not exceed the set pressure by more than 3% or 2 psi (13.8 kPa), whichever is greater, for steam, and 10% or 3 psi (20.6 kPa), whichever is greater, for air, gas, or liquid service. NB-7522.4 Sensing Mechanism Integrity. For other than spring loaded direct acting pilot control devices, means shall be provided to detect failure of the pressure sensing element, such as bellows, when operation of the pilot control device is dependent upon the integrity of a pressure sensing element. NB-7522.5 Set Pressure Tolerance (a) The set pressure tolerance shall apply only to the pilot valve. (b) The set pressure tolerance plus or minus shall not exceed the following: 2 psi (13.8 kPa) for pressures up to and including 70 psi (483 kPa), 3% for pressures over 70 psi (483 kPa) for liquid valves and 3% for pressures over 70 psi (483 kPa) up to and including 300 psi (2070 kPa), 10 psi (69 kPa) for pressures over 300 psi (2070 kPa) up to and including 1000 psi (6900 kPa), and 1% for pressures over 1000 psi (6900 kPa) for steam, air, and gas valves. The set pressure tolerance as stated shall apply unless a greater tolerance is established as permissible in the Overpres- sure Protection Report (NB-7200) and in the valve Design Specification (NCA-3250). (c) Conformance with the requirements of (b) above shall be established for each production valve by test. Steam valves shall be tested on steam, air or gas valves on air or gas, and liquid valves on liquid. NB-7522.6 Blowdown (a) The blowdown requirements shall only apply to the pilot valve. (b) Pilot operated valves shall be adjusted to close after blowing down to a pressure not lower than 95% of the set pressure for steam, unless a different percent- age is specified in the valve Design Specification (NCA- 3250) and the basis for the setting is covered in the Overpressure Protection Report (NB-7200). For all other fluids, pilot operated valves shall be adjusted to close after blowing down to a pressure not lower than that specified in the valve Design Specification (NCA-3250), and the basis for the setting shall be covered in the Overpressure Protection Report (NB-7200). docsity.com