1、Piping Guide forControl CentersApproved 31 May 1981ISARP60.91981RECOMMENDED PRACTICEISA The Instrumentation,Systems, andAutomation Society TMCopyright 1981by the Instrument Society of America. All rights reserved. Printed in the UnitedStates of America. No part of this publication may be reproduced,
2、 stored in a retrieval system, ortransmitted in any form or by any means (electronic, mechanical, photocopying, recording, orotherwise), without the prior written permission of the publisher.ISA67 Alexander DriveP.O. Box 12277Research Triangle Park, North Carolina 27709ISARP60.91981, Piping Guide Fo
3、r Control CentersISBN 0-87664-556-2ISA-RP60.9-1981 3PrefaceThis Preface is included for information purposes and is not part of ISA-RP60.9-1981.This Standard has been prepared as a part of the service of the ISA toward a goal of uniformity in the field of instrumentation. To be of real value, this d
4、ocument should not be static, but should be subject to periodic review. Toward this end, the Society welcomes all comments and criticisms, and asks that they be addressed to the Secretary, Standards and Practices Board, ISA, 67 Alexander Drive, P.O. Box 12277, Research Triangle Park, NC 27709, Telep
5、hone (919) 549-8411, e-mail: standardsisa.org.The ISA Standards and Practices Department is aware of the growing need for attention to the metric system of units in general, and the International System of Units (SI) in particular, in the preparation of instrumentation standards. The Department is f
6、urther aware of the benefits to USA users of ISA Standards of incorporating suitable references to the SI (and the metric system) in their business and professional dealings with other countries. Towards this end this Department will endeavor to introduce SI-acceptable metric units in all new and re
7、vised standards to the greatest extent possible. The Metric Practice Guide, which has been published by the American Society for Testing and Materials as ANSI designation Z210.1 (ASTM E380-76, IEEE Std. 268-1975), and future revisions, will be the reference guide for definitions, symbols, abbreviati
8、on, and conversion factors.It is the Policy of the ISA to encourage and welcome the participation of all concerned individuals and interests in the development of ISA Standards. Participation in the ISA Standards making process by an individual in no way constitutes endorsement by the employer of th
9、at individual of the ISA or any of the Standards which ISA develops.The SP60 Committee is preparing a series of recommended practices on control centers. ISA-RP60.9 is the second of this series to be published. The published recommended practices and drafts in preparation are listed below:RECOMMENDE
10、D PRACTICESECTION TITLEdRP60.1* Control Center (C.C.) FacilitiesdRP60.2* C. C. Design Guide and TerminologydRP60.3* Human Engineering for Control CentersdRP60.4* Documentation for Control CentersdRP60.5* Control Center Graphic DisplaysdRP60.6* Nameplates, Tags and Labels for ControlCentersdRP60.7* C
11、ontrol Center ConstructionRP60.8 Electrical Guide for Control Centers (published 1978)RP60.9 Piping Guide for Control Centers (published 1981)*Draft Recommended Practice, for additonal information on the status of this document contact ISA Headquarters.4 ISA-RP60.9-1981dRP60.10* Control Center Inspe
12、ction and TestingdRP60.11* Crating, Shipping and Handling for C.C.The persons listed below served as active members of the ISA Control Centers Committee for the major share of its working period:NAME COMPANYH. R. Solk, Chairman ConsultantC. S. Lisser - Past Chairman Oak Ridge National LaboratoryR. W
13、. Borut - Past Chairman The M. W. Kellogg CompanyJ. M. Fertitta, Secretary The Foxboro CompanyA. R. Alworth Shell Oil CompanyM. Arevalo Fischer & Porter CompanyC. D. Armstrong Tennessee Valley AuthorityB. Carlisle E.I. duPont deNemours & Company, Inc.J. M. Devenney E.I. duPont deNemours & Company, I
14、nc.J. Farina Gismo Division of GECO, Guarantee Electric CompanyC. H. Goding BIF, Unit of General SignalJ. Gump The Riley CompanyR. E. Hetzel Stauffer Chemical CompanyT. P. Holland Johnson Controls, Inc.Panel UnitA. A. Kayser Bristol Division of ACCOW. H. Kelley (Deceased) Bechtel Associates Professi
15、onal CorporationJ. L. Kern Monsanto CompanyR. W. Kief Emanon Company, Inc.S. F. Luna Gulf General AtomicsJ. G. McFadden Public Service Electric & GasR. Munz The Mundix CompanyF. Nones The Foxboro CompanyW. A. Richards (Deceased) General Electric CompanyA. Stockmal Owen-Illinois, Fecker Systems Divis
16、ionM. J. Walsh Procon, Inc.R. L. Welch El Paso Natural Gas CompanyW. T. Williams Robertshaw Controls CompanyB. W. Ball Brown & Root, Inc.C. F. Aured Panels, Inc.R. F. Rossbauer Fischer & Porter CompanyR. A. Landthorn Panels, Inc.J. F. Jordan Monsanto CompanyISA-RP60.9-1981 5The persons listed below
17、served as corresponding members of the ISA Control Centers Committee for the major share of its working period:NAME COMPANYJ. Cerretani Detroit Edison CompanyN. L. Conger Continental Oil CompanyL. Corsetti Crawford & Russell, Inc.T. J. Crosby Robertshaw Controls CompanyC. R. Davis EngineerH. L. Faul
18、 A-E Development CorporationL. Ferson ISA HeadquartersM. E. Gunn Swanson Engineering & ManufacturingR. I. Hough Hough AssociatedW. B. Miller Moore Products CompanyH. Kamerer Wilmington Sheet Metal, Inc.A. L. Kress 3M CompanyA. J. Langelier EngineerR. G. Marvin RetiredA. P. McCauley, Jr. Diamond Sham
19、rock Corp.C. W. Moehring BechtelD. P. Morrison BIF/General SignalR. L. Nickens Reynolds Metal CompanyH. P. Fabisch Fluor Engr. & Constructors, Inc.F. W. Reichert EngineerJ. F. Walker Honeywell, Inc.G. Walley The N/P CompanyW. J. Wylupek Industry Appl. EngineeringJ. R. Jordan International Paper Comp
20、anyThis Recommended Practice was approved for publication by the ISA Standards and Practices Board in May 1981.NAME COMPANYT. J. Harrison, Chairman IBM CorporationP. Bliss ConsultantW. Calder The Foxboro CompanyB. A. Christensen Continental Oil CompanyM. R. Gorden-Clark Scott Paper CompanyR. T. Jone
21、s Philadelphia Electric CompanyR. Keller Boeing CompanyO. P. Lovett, Jr. Jordan ValveE. C. Magison Honeywell, Inc.A. P. McCauley Diamond Shamrock CorporationE. M. Nesvig ERDCO Engineering CorporationR. L. Nickens Reynolds Metals Company6 ISA-RP60.9-1981G. Platt Bechtel Power CorporationR. Prescott M
22、oore Products CompanyR. W. Signor General Electric CompanyW. C. Weidman Gilbert Associates, Inc.K. A. Whitman Allied Chemical CorporationL. N. Combs* R. L. Galley*R. G. Marvin*W. B. Miller* Moore Products CompanyJ. R. Williams* Stearns-Rogers, Inc.*Director EmeritusISA-RP60.9-1981 7Contents1 Scope .
23、 92 Definitions . 92.1 Piping . 92.2 Field piping 92.3 Direct process piping . 92.4 Signal piping 92.5 Air 92.6 Pneumatic supply 92.7 Signal air 93 General . 103.1 Application . 103.2 Reference standards or recommended practices 104 Pneumatic piping 104.1 Pneumatic supply 104.2 Signal piping 134.3 F
24、ittings . 145 Direct process piping . 15ISA-RP60.9-1981 91 ScopeThis Recommended Practice is intended to assist the designer or engineer in the definition of piping requirements for pneumatic signals and supplies in control centers. This Recommended Practice is based on current practices. Because of
25、 the special nature of each control center, specific rules are not practical and accepted guidelines should take precedence. This Recommended Practice is a presentation of these guidelines.Piping external to the control center (Field Piping) is beyond the scope of this document.2 Definitions2.1 Pipi
26、ngFor the purpose of this document, the term “piping“ includes metal or plastic tube, pipe fittings, valves, and similar components, and the practice of assembling these items into a system.2.2 Field pipingThat piping connecting the control center to items external to the control center.2.3 Direct p
27、rocess pipingThat piping between the process and the control center which contains process fluid.2.4 Signal pipingThat piping interconnecting instruments, instrument devices, or bulkhead fittings.2.5 AirFor the purposes of this document, air implies use of any suitable, and normally clean, dry, safe
28、 gas.2.6 Pneumatic supplyAir at a nominally constant pressure used to operate pneumatic devices.2.7 Signal airAir at varying pressure used to represent process or control information.10 ISA-RP60.9-19813 General3.1 ApplicationPiping is employed in control centers to convey air for two basic reasons:
29、(a) that of supplying energy for the operation of instruments and other devices, and (b) that of transmission of information between instruments. Integrity of the piping system is essential to avoid loss of the pneumatic supply and degradation of the transmitted signals.3.2 Reference standards or re
30、commended practices3.2.1 ISA-S7.3 Quality Standard for Instrument Air3.2.2 ISA-RP42.1 Nomenclature for Instrument Tubing Fittings (Threaded)3.2.3 ISA-RP7.1 Pneumatic Control Circuit Pressure Test3.2.4 ISA-S7.4 (SAMA* RC2-5) Air Pressures for Pneumatic Controllers and Transmission Systems3.2.5 SAMA*
31、RC19-10 Tubing Connection Markings for Pneumatic Instruments.3.2.6 ISA dRP60.6* Nameplates, Tags and Labels for Control Centers3.2.7 API* RP 550, Part 1, Section 12 Control Centers4 Pneumatic piping4.1 Pneumatic supplySupply air is usually delivered to the control center from external sources at pre
32、ssures typically between 60 and 150 psi gage (4001000 kPa). It should be clean, dry, and suitable for the application and environment. Refer to ISA-S7.3, “Quality Standard for Instrument Air.“ A sufficient flow of supply air should be available to meet the control center requirements for transient a
33、s well as steady state conditions. Displacement of oxygen in the control center or control room, resulting from the use of bleed type instruments when gases other than air are used, should be considered.4.1.1 Pressure reducing stationA pressure reducing station (sometimes termed as “air set“) reduce
34、s and regulates the supply air pressure to a level suitable for the application. The reduced pressure is usually 20 psi gage (140 *Scientific Apparatus Makers Association*Draft Recommended Practice, for additional information on the status of this document contact ISA Headquarters.*American Petroleu
35、m InstituteISA-RP60.9-1981 11kPa) for systems employing 315 psi gage (20100 kPa) signal ranges and 40 psi gage (270 kPa) for 630 psi gage (40200 kPa) signal ranges.Pressure reducing stations are normally located inside of the control center, but can be external if special access requirements or spac
36、e limitations exist.4.1.1.1 SizingThe number of air users in the control center establishes the capacity requirements. It is a common practice to determine the total instantaneous air usage by adding together the maximum consumption of each pneumatic device and multiplying by a safety or sizing fact
37、or of 1.3 to 2.0.Air filters and pressure regulators are selected from manufacturers capacity data based on the total adjusted instantaneous usage and required regulated pressure.4.1.1.2 DesignAn installation of dual pressure regulators and dual air filters is generally employed. They are arranged i
38、n parallel with appropriate valving so that one system can be serviced while the other is in use. (See Figure 1.) When 3-way valves are used, they should not interrupt supply to the instruments during a transfer from one leg to the other. Pressure gages should be provided in each leg to indicate the
39、 pressure of the regulated air. A pressure gage may also be installed to indicate the pressure of the supply air. A pressure gage with a blow-out back or disc and a plastic lens is recommended. Low air pressure alarms are often initiated from suitable pressure switches at the pressure reducing stati
40、on. Adequate clearance is necessary to provide for service and maintenance of the system.Figure 1 Installation of dual pressure regulators and dual air filters12 ISA-RP60.9-1981Combination filter-regulators can be employed where the air usage or service requirements permit. (See Figure 2.) On contro
41、l centers with a few air users, a separate air filter and pressure regulator may be employed for each air user.Figure 2 Installation of combination filter-regulators4.1.2 Regulated air supply headerThe regulated air is normally piped to a larger diameter plastic or non-ferrous metal pipe section act
42、ing as a manifold or header and reservoir from which each air user receives its supply. The headers are normally installed in a horizontal or vertical plane in the lower part of the control center and have individual shut-off valves at each air supply take-off point. Each shut-off valve should be id
43、entified with a non-corrosive metal or plastic tag. Refer to ISA-dRP60.6 “Nameplates, Tags and Labels for Control Centers.“* (See Figure 3.) It is a good practice to provide up to 15 percent spare valved connections. The assembly is normally mounted in a rigid manner, sloping at least 1/8 inch per f
44、oot away from the supply end, down toward a drain cock. If there is the possibility that failure of the pressure reducing station could result in over pressure damage to the air users, a suitably sized safety relief valve should be installed. (See Figures 1, 2, and 3.) The safety relief valve should
45、 be sized to pass the rated flow capacity of one regulator failing full open.The individual air users are connected to the header shut-off valves by tubing. This supply tubing is typically 1/4 inch outside diameter soft copper, plastic, or stainless steel. Some devices with larger air usage may requ
46、ire supply tubing of 3/8 inch or 1/2 inch outside diameter, as suggested by the specifications for that device.It is a general practice to increase the volume of the air supply header as the number of air users increases. To minimize the pressure drop across the air supply header during large transi
47、ents in air demand, it is a common practice to use larger diameters and longer sections of pipe.*Draft Recommended Practice, for additional information on the status of this document contact ISA Headquarters.ISA-RP60.9-1981 13Figure 3 Air supply header4.2 Signal pipingSignal piping is typically 1/4
48、inch outside diameter (OD) metal or plastic tubing. The signal piping system often includes a test tee and isolating valve at each receiving device to facilitate testing, calibration, or maintenance.4.2.1 Common materialsa) Soft Copper, 1/4 in. OD x 0.030 in. wall thicknessb) Polyethylene, 1/4 in. O
49、D x 0.040 in. wall thicknessc) Aluminum, 1/4 in. OD x 0.032 in. wall thicknessd) Stainless Steel, 1/4 in. OD x 0.030 in. wall thicknessCertain applications may require plated or plastic coated metal tubing.4.2.2 Labeling and color codingPlastic or noncorrosive metal nametags should be attached to bulkhead fittings to identify signal source, application, and/or other information. Refer to ISA-dRP60.6, “Nameplates, Tags and Labels for Control Centers.“* Color coded plastic tube can identify use of application, i.e.:air supply REDtransmitted measurement ORANGE con
