1、“- - ASNE N.L 75 m 075w0 0050284 0 m “-G -2+q . AMERICAN NATI0NA.L STANDARD a REACTOR. PLANTS A.ND THEIR MAINTENANCE - ASME N2784 75 m 0757670 0050285 2 W AMERICAN NATIONAL STANDARD An American National Standard implies a consensus of those substantially concerned with its scope and provisions. An A
2、merican National Standard is intended as a guide to aid the manufacturer, the consumer, and the general public. The existence of an American National Standard does not in any respect preclude anyone, whether he has approved the standard or not, from manufacturing, marketing, purchasing, or using pro
3、ducts, processes, or procedures not conforming to the: standard, American National Standards are subject to periodic review, and users are cautioned to obtain the latest editions. CAUTION NOTICE: This American National Standard may be revised or withdrawn at any time. The procedures of the American
4、National Standards Institute require that action be taken to reaffirm, revis, or withdraw this standard no later than five years from date of pub- lication. Purchasers of American National Standards may receive current information on all standards by calling or writing the American National Standard
5、s Institute. This standard was approved by the American National Standards Committee N45 and its Secretariat, and it was subsequently approved and designated N278.1-1975 by the American National Standards Institute on September 18, 1975. No part of this document may be reproduced in any form, in an
6、electronic retrieval system or otherwise, without the prior written permission of the publisher, THE AMERICAN SOCIETY OF MECHANICAL ENGINEERS Copyright O 1976 by All Rights Reserved Printed in U.S.A. FOREWORD (This foreword is not part of American National Standard Self-operated.and Power-operated S
7、afety-Related . Valves Functional Specification Standard) This standard is one of a series of power plant equipment standards provided to assure that safety-related equipment will function as specified. -The standard was developed under sponsorhip of the American Society of Mechanical -Engineers (AS
8、ME) as an effort by the American National Standards Committee N45 . on Reactor Plants and Their Maintenance. This committee has been chartered to promote the development . of standards for the location, design, construction, and maintenance of nuclear reactors and plants embody- ing nuclear reactors
9、, including equipment, methods, and components specifically for this purpose. In October of 1972, the N45 Committee of ANSI established a task force to prepare a series of standards to assure that safety-related valves would function as specified. This standard provides for the specification . of th
10、e required functional characteristics of these valves. Utilization of this standard will provide assurance that the functional requirements of valves are fully described so tht valves can be designed to provide safe, reliable operation for all foreseeable conditions including preoperational tests an
11、d extreme limits of plant design conditions. . Suggestions for improvement gained in the use of this standard will be welcomed, They should be sent to the Secretary, American National Standards Committee N45, The American Society of Mechanical Engi- neers, United Engineering Center, 345 East 47th St
12、reet, New York, New York 10017. ASME N278.L 75 W 0757670 0050287 6.m . AMERICAN NATIONAL STANDARDS COMMITTEE N45“ Reactor Plants and Their Maintenance OFFICERS , . Sol Burstein, Chairman S. A. Bernsen, Vice-Chairman Manuel Gutierrez, Secretary COM.MlTTEE PERSONNEL AMERICAN FEDERATION OF LABOR AND CO
13、NGRESS OF INDUSTRIAL ORGANIZATIONS P, R. Shoop, International Brotherhood of Electrical Workers, Washington, D.C. AMERICAN NUCLEAR SOCIETY . J. S. Moore, Westinghouse Electric Corporation, Pittsburgh, Pennsylvania J. R. Rohlfs, North American Rockwell, Canoga Park, California AMERICAN SOCIETY OF CIV
14、IL-ENGINEERS A. A. Ferlito, Ebasco Services, New York, New York. C. 8. Mjczek, Stone and Webster Engineering Corporation, Boston, Massachusetts AMERICAN SOCIETY OF MECHANICAL ENGINEERS, THE E. C. Bailey, Commonwealth Edison Cmpany, Chicago, Illinois V. S. BOyer, Philadelphia Electric Company, Philad
15、elphia, Pennsylvania H. F. Brush, Bechtel Corporation, San Francisco, California S Burstein, Wisconsin Electric Power Company, Milwaukee, Wisconsin AMERICAN WELDING SOCIETY J. R. Mc Guffey, Union Carbide Corporation, Oak Ridge, Tennessee H. E. Broadbent, alternate, American Welding Society, Miami, F
16、lorida. ATOMIC INDUSTRIAL FORUM, INC. D. W. -Montgomery, Babcock Maintenance-Requirements, see Section 3,8 follwing. tion 3 .$ 3.6 - a. Power-operated . b. Self-operated c. Pressure relief d. Frequent use - . e. Infrequent use g. Nomifial leakage - h. Normally open .i. Normally closed 3.1 .I Frequen
17、t use i$ defined as requiring func- tional operation, including exercising and testing, in excess of 500 times over the life of the valve. 3.1.2 Low leakage is defmed as valves in which the Manufacturers main seatleakage acceptance test limit is 2cubic centimeters of water per hour per inch of diame
18、ter of nominal valve size. 3.1.3 Nominal leakage is defined as valves in which the Manufacturers main seat leakage accep- tance test limit is 10 cubic centimeters of water per hour per inch of diameter. of nominal valve size. 3.1,4 The leakage definitions described above are not applicable to those
19、flow-control valves which are -not. intended to also serve as isolation or stop valves. 3.2 Structural Requirements . f. Low leakage The followingnformation shall be specified. a. The design pressure and temperature . b. The normal operatitlg pressure and- tempera- ture. c. The flow capaciy at a sta
20、fed pressure differ- ential. d. Time-temperature data for significant thermal transients, with number of cycles (see ASME Boiler and Pressure Vessel Code, Section III e. The seismic acceleration and. dynamic loadings that the. valve assembly shall be capable of - NB 3500). 3.1 Valve Application Char
21、acteristics withstanding without 10s of functional capa- - bility. The application characteristics of each valve hall f. Loadings from structural spports and re- be .identified by listing whichever o the following de- straints acting directly on valve, if any. .scriptive terms are appropriate. . g.
22、Fundamental frequency of valve assembly. ASME N278.1 75 e t 0757b70 0050272 T m. 1 SELF-OPERATED AND POWER-OPERATED SAFETY-RELATED AMERICAN NATl0.NAL STANDARD VALVES FUNCTIONAL SPECIFICATION STANDARD . 3.3 Operational Requirements Anticipated modes of valve operating including safety-related functio
23、n (i.e., open, close, remain as-is, etc.) shall be specified. The operating conditions, . power versus operation condition, and environmental conditions shall .be identified. 3.3.1 Operating Conditions. The number of operational cycles, differential .pressure (amount and direction), system fluid, fl
24、ow (quantity and direction), imposed loads, temperature, and pressure Condition for each of the following operational categories shall be specified, -a. Installation Testing . . b. System Hydrostatic Testing c. Preoperational Testing d. Start-up Testing e, Normal and Abnormal Plant Operation, in- cl
25、uding postulated accident conditions . - f. In-service Testing and Exercising Other operational conditions such as likelihood of bonnet pressurization caused by volumetric expan- sion of contained fluid, dry operation, etc., shall be identified. For check valves, flow rates shall be stated for all o
26、perating conditions with maximum total time at each condition. 3.3.2 Power Versus Operation Conditions. The power supply conditions shall be specified as follows: a. Normal voltage and frequency or normal Bc- tuator fluid pressure under normal operating conditions. . b. High voltage limit and freque
27、ncy or maximum actuator fluid pressure under most severe function requirement. c. d. Type and degree of filtration, including micron size, particulates, dewpoint, etc., as applicable. e. Actuator signal; type and range of signal (eleo tric, pneumatic, etc.) and required valve re- . sponse with incre
28、asing and decreasing signal. 3.3.3 Environmental Conditions, .The environ- -mental conditions which are postulated to exist at a time safety-related function is required shall be iden- tified and specified. . . The need of valve, actuator and actuator acces- sories to survive normal and abnormal env
29、ironmental conditions, with or without maintenance shall be stated, The following factors are considered relevant, a. The atmosphere including chemistry, pressure, temperature, humidity and radioactivity in . which the valves will be installed and must operate under normal conditions. b. The atmosph
30、ere including. chemistry, pressure, temperature, humidity and radioactivity in , which the valves must operate under abnormal (including accident) conditions. The duration of these conditions shall. be specified, 3.4 Seat Leakage Limits follows, Seat leakage limits for.valves shall be identified as
31、a. Acceptance leakage limits for safety relief valves shall be specified as to limits at percent- age of set point b. Acceptance .leakage hits for main closure element for valves identified as “low leakage” - and “nominal leakage” shall be as defined in . subparagraphs 3.1.2 and 3.1.3, pressure diff
32、erential shall be identified. c. As applicable, the direction of leakage and 3.5 Pressure Relief Valve Characteristics For pressure relief valves the following, as appli- . cable, shall be specified, a. Fluid b. Set pressure c. Set pressure range d. Set pressure.tolerance e. Discharge capacity with
33、due allowance for the effect of the back pressure on the capacity f, Overpressure (pressure increase over the set pressure) g. Blowdown (difference between actual pop- ping pressure and actual reseating pressure) AMERICAN NATIONAL STANDARD SELF-OPERATED AND POWER-OPERATED SAFETY-RELATED VALVES FUNCT
34、IONAL SPECIFICATION STANDARD ANSI N278.1-1975 h. Static and dynamic back pressure, minimum and maximum i. Response time (maximum time delay between attainment of set pressure or reception of the energizing signal by the solenoid and valve lift) 3.6 Special Material Requirements Unique material requi
35、rements of the valve, ac- tuator and actuator controls shall be specified. Items to be considered shall include, but not be limited to the following. a. Unacceptable part or trim materials b. Halogen limits for gaskets and packing c. Limitations on nonferrous materials, internal (wetted) or external
36、 3 d. Special surface preparations or coatings re- e. Unusual pro&ss fluid chemistry quired 3.7 Installation Requirements The valve orientation shall be specified if unusual. Pressure relief valve piping arrangements and, where used, details of water seal arrangements shalt be de- scribed. 38 Maintenance Requirements Special provision for valve maintenance shall be specified.
