1、AMSC N/A FSC 6685DISTRIBUTION STATEMENT A . Approved for public release; distribution is unlimited.INCH-POUNDMIL-PRF-2940D13 April 1999SUPERSEDINGMIL-S-2940C1 November 1994PERFORMANCE SPECIFICATIONSNUBBERS, FLUID PRESSURE, INSTRUMENT PROTECTIONThis specification is approved for use by all Department
2、s and Agenciesof the Department of Defense.1. SCOPE1.1 Scope . A snubber covered by this specification is a pressuretransmission device which restricts the rate of fluid flow to a pressuresensing instrument and, as a result, the rate of pressure change.1.2 Classification . Snubbers covered by this s
3、pecification areclassified according to the following characteristics, as specified (see 6.2).EXAMPLE :M2940 - 1 - L - A - P - G Type Class Composition End Cleanliness(see (see (see 1.2.3) connection (see 1.2.5)1.2.1) 1.2.2) (see 1.2.4)1.2.1 Types . The type of service in which the snubber will be u
4、sedwill be designated by one of the following numbers and should be selectedbased on the expected fluid at the snubber location:Type Service1 Oils, hydraulic fluid above 20 centistokes( cSt). Oil above 225 Saybolt seconds universal(SSU) at operating temperatures.2 Fresh water, steam, gasoline, light
5、 oils below20 cSt.3 Gases.4 Seawater.Beneficial comments (recommendations, additions, deletions) and any pertinentdata which may be of use in improving this document should be addressed to: Commander, SEA 03Q, Naval Sea Systems Command, 2531 Jefferson Davis Hwy,Arlington, VA 22242-5160 by using the
6、Standardization Document ImprovementProposal (DD Form 1426) appearing at the end of this document or by letter.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-PRF-2940D21.2.2 Class . The range of operating pressures is designated by thefollowing
7、letters:Class Operating range limitL 10 to 1000 pounds per square inch gauge ( psi).H 1001 to 6000 psi.1.2.3 Composition . The material composition of the snubber (see 3.2)is designated by one of the following letters:Composition MaterialA Copper nickel alloyB Nickel-copper ( monel) alloyC Corrosion
8、 resisting steelX Other1.2.4 End connection . The configuration for the snubbers endconnection is designated by one of the following letters (see 3.3.2):End connection ApplicationP Pressure gauge general applications(see 3.3.2.1.1).F Pressure gauge flareless (bite type)applications (see 3.3.2.1.2).T
9、 Pressure transducer general applicat ions(see 3.3.2.2).S Other applications (see 6.2). The endconnections must be specified in the contractordering data.1.2.5 Cleanliness . The level of cleanliness of the snubber isdesignated by one of the following letters:Cleanliness ApplicationG General applicat
10、ions.X Oxygen and dry nitrogen applications.Z Special cleaning (see 6.2).2. APPLICABLE DOCUMENTS2.1 General . The documents listed in this section are specified insections 3 and 4 of this specification. This section does not includedocuments cited in other sections of this specification or recommend
11、ed foradditional information or as examples. While every effort has been made toensure the completeness of this list, document users are cautioned that theymust meet all specified requirements documents cited in sections 3 and 4 ofthis specification, whether or not they are listed.2.2 Government doc
12、uments .2.2.1 Specifications, standards, and handbooks . The followingspecifications, standards, and handbooks form a part of this document to theextent specified herein. Unless otherwise specified, the issues of thesedocuments are those listed in the issue of the Department of Defense Index ofSpeci
13、fications and Standards ( DoDISS) and supplement thereto, cited in thesolicitation (see 6.2).Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-PRF-2940D3SPECIFICATIONSDEPARTMENT OF DEFENSEMIL-S-901 - Shock Tests, H.I. (High-Impact) ShipboardMachine
14、ry, Equipment, and Systems,Requirements for.MIL-PRF-17331 - Lubricating Oil, Steam Turbine and Gear,Moderate Service.MIL-F-18866 - Fittings, Hydraulic Tube, Flared, 37 Degreeand Flareless, Steel.STANDARDSDEPARTMENT OF DEFENSEMIL-STD-167-1 - Mechanical Vibrations of Shipboard Equipment(Type I - Envir
15、onmental and Type II -Internally Excited).MIL-STD-1330 - Cleaning and Testing of Shipboard Oxygen,Nitrogen and Hydrogen Gas Piping Systems.MS16142 - Boss, Gasket Seal Straight Thread TubeFitting, Standard Dimensions for.(Unless otherwise indicated, copies of federal and mili tary specifica-tions, st
16、andards, and handbooks are available from the StandardizationDocument Order Desk, 700 Robbins Avenue, Bldg. 4D, Philadelphia, PA 19111-5094.)2.3 Non-Government publication .ASTM E 527 - Practice for Numbering Metals and Al loys (UNS).SAE J 1086 - Numbering Metals and Alloys.2.4 Order of precedence .
17、 In the event of a conflict between the textof this document and the references cited herein, the text of this documenttakes precedence. Nothing in this document, however, supersedes applicablelaws and regulations unless a specific exemption has been obtained.3. REQUIREMENTS3.1 First article . When
18、specified (see 6.2), a sample shall besubjected to first article inspection s in accordance with 4.2.3.2 Material . Material for wetted parts shall be selected for longterm compatibility with the service fluid (see 1.2.1) and theenvironment in which they operate. Material for wetted parts shallbe eq
19、ual to or superior in corrosion resistance to that used in thebody except that corrosion resistant steel is prohibited for type 4(seawater) snubbers and for oxygen service. When copper-nickel,nickel-copper, or corrosion resistant steel alloys are used, theyshall be identified as listed below. All ot
20、her materials shall beidentified as composition “X”.Composition A - Copper-nickel alloys (C70600 and C71500).Composition B - Nickel-copper ( monel) (55-70 percent nickel).Composition C - Corrosion resistant steel (S30400, S30403, S31600,S31603, S32100, and S34700).Composition X - Material, other tha
21、n above.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-PRF-2940D4The material used in the body of the snubber shall be included in the marking(see 3.3.4) using the Unified Numbering System (UNS) designation in accordancewith SAE J 1086, and ASTM
22、 E 527.3.2.1 Recycled, recovered, or environmentally preferable materials . Recycled, recovered, or environmentally preferable materials should be used tothe maximum extent possible provided that the material meets or exceeds theoperational and maintenance requirements and promotes economicallyadvan
23、tageous life cycle costs.3.2.2 Nonmetallic materials . Nonmetals shall be moisture and flameresistant, shall not support fungus, insect, or bacteria growth, and shall notbe adversely affected by the ambient environments specified in theconfiguration and performance requirements of this specification
24、. Nonmetalsshall not chemically react, degrade, or outgas when subjected to thefollowing: air, distilled water, seawater, salt, petroleum and silicone basedoils, oil solvents, prolonged (greater than one month) periods of exposure toambient temperatures, prolonged periods of exposure to elevated tem
25、peratures(up to 350 degrees Fahrenheit ( F), and exposure to prolonged cycling periodsfrom ambient to elevated temperatures. Any material which provides a nutrientmedium for fungus and insects shall not be used.3.2. Porous metal . Snubbers with a porous metal composition (internalparts and configura
26、tion) are prohibited for gas (type 3) and for seawater(type 4) service (see 1.2.1). When used for oil or water (type 1 or 2)service, snubbers with porous metal compositions shall only be employed insystems with particulate contaminants less than 25 micrometers in size.3.3 Configuration . Snubbers sh
27、all contain no electrical or electroniccomponents.3.3.1 Snubber body size . The length of the assembled snubber bodyshall be not greater than 4 inches. The body shall have hexagonal cross-sections of sufficient widths to allow the use of a wrench for installing andremoving. The distance across the f
28、lats shall be not less than 0.375 inch norgreater than 1.25 inches. The maximum diameter of the snubber body shall benot greater than 2.0 inches.3.3.2 End connections .3.3.2.1 General pressure gauge applications . Snubbers used in pressuregauge applications shall be as follows.3.3.2.1.1 O-ring union
29、 connection . Snubbers used for O-ring unionpressure gauge application shall have 9/16-18 UNF-3A external threads on theinlet connection and 9/16-18 UNF-3B internal threads on the outlet connectionin accordance with Drawing 803-1385850. When specified (see 6.2), eachsnubber shall be furnished with a
30、 union nut, tailpiece, and O-ring.3.3.2.1.2 Flareless (bite type) connection . Snubbers used forflareless (bite type) pressure gauge applications shall have 7/16-20 UNF-2Aexternal threads on the inlet connection and 7/16-20 UNF-2B internal threadson the outlet connection in accordance with MIL-F-188
31、66, 6000 psi for 1/4-inchtubing.3.3.2.2 General pressure transducer applications . Snubbers used forpressure transducer applications shall have a 7/16-20 UNF flareless tubeconnection (1/4 inch outside diameter ( od) in accordance with MIL-F-18866 onthe inlet connection. The outlet connection shall b
32、e 7/16-20 UNF-2A externalProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-PRF-2940D5thread to mate with the MS16142 female connection port of the pressuretransducer. An O-ring shall be supplied on the outlet connection.3.3.3 Cleaning . The snubber
33、 body and all parts that come into contactwith the service fluid shall be free of all loose scale, rust, grit, fillings,and free of mercury, calibration liquids, oil, grease, solvents, and otherorganic materials. Type 3 snubbers for oxygen or nitrogen service shall becleaned in accordance with MIL-S
34、TD-1330.3.3.4 Marking . Each snubber shall be metal stamped or otherwisepermanently marked with the maximum working pressure, classification (see 1.2)and manufacturers stamp or trademark. The material composition shall beincluded in the marking identified by the UNS (see 3.2). The maximum workingpre
35、ssure shall be followed by the abbreviation “ psi.“ (For example: 6000 psiM2940-1HBPG *. *manufacturers stamp or trademark and UNS, as applicable.)3.3.4.1 Flow direction . The direction of flow through the snubbershall be indicated by an arrow with the word “gauge“ at the point of thearrow. The arro
36、w shall be raised from the surface or etched into the surfacein a permanent manner and to the extent that it can be easily identified byhuman touch. The word “gauge“ shall be metal stamped or otherwise permanentlymarked.3.3.4.2 Type 3 snubbers shall have a warning label included on itsprimary pack m
37、arked “oxygen“ or “nitrogen“ service, as applicable for thesystem use when cleaned for these services.3.4 Performance .3.4.1 Steady state transmission . The difference in indicated outputwith and without the snubber under test shall be within the accuracy limits ofthe pressure transducer or pressure
38、 gauge employed when tested as specified in4 . 6 . 1.3.4.2 Dampening . The pressure as indicated by the test pressuretransducer shall satisfy both the following criteria when tested as specifiedin 4 . 6 . 2:(a) Indicate a pressure of 25 percent or less of the finalsteady state pressure at a time equ
39、al to that at whichthe monitoring pressure transducer initially reaches itsstep pressure level.(b) Reach at least 90 percent of its final steady state pressurein not more than 2.5 seconds after initiation of thepressure step as indicated by the monitoring transducer.3.4 .3 Temperature . The snubber
40、under test shall show no evidence ofleakage or damage as a result of the temperature test specified in 4.6.3. Thesnubber under test shall meet the dampening requirement of 3.4.2 after thehigh temperature, low temperature, and temperature cycling portions of 4.6.3.3.4.4 Vibration . The snubber under
41、test shall show no indication ofleakage or damage as a result of the vibration testing specified in 4.6.4. Upon completion of the vibration test, the snubber shall meet the dampeningrequirement of 3.4.2.3.4.5 Shock . The snubber under test shall show no indication ofleakage or damage as a result of
42、the shock testing specified in 4.6.5. Uponcompletion of the shock test, the snubber under test shall meet the dampeningrequirement as specified in 3.4.2.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-PRF-2940D63.4.6 Pressure integrity . The snub
43、ber under test shall withstand the pressure specified in 4.6.6 without showing any evidence of leakage or damage.Upon completion of the pressure integrity test, the snubber under test shallmeet the dampening requirement of 3.4.2.3.5 Cleaning and surface finishes . Surfaces of castings, forgings,mold
44、ed parts, stampings, machined, and welded parts shall be free of defectssuch as cracks, porosity, undercuts, voids, and gaps as well as sand, dirt,fins, sharp edges, scale, flux, and other harmful or extraneous materials. External surfaces shall be smooth and edges shall be either rounded orbeveled.
45、 There shall be no burn-through. There shall be no warpage ordimensional change due to heat from welding operations. There shall be nodamage to adjacent parts resulting from the welding.4. VERIFICATION4.1 Classification of inspections . The inspection requirementsspecified herein are classified as f
46、ollows:(a) First ar ticle inspection (see 4.2).(b) Conformance inspection (see 4.3).4.2 First article inspection . First article inspection shall beperformed and passed prior to production and shall be witnessed by aGovernment inspector. First article inspection shall be performed on sampleswhich ha
47、ve been produced with equipment and procedures normally used inproduction. First article inspection shall consist of the examination andtests specified in table I and in the sequence listed.4.2.1 Sample size . Two snubber samples of each type, class,composition, and end connection shall be subjected
48、 to the first articleinspection.TABLE I. Inspection, examination, and tests .Inspection RequirementTestproceduresFirst articleinspectionConformanceinspectionExamination 3.2, 3.3, 3.5 4.5 X XSteady statetransmission3.4.1 4.6.1 X -Dampening 3.4.2 4.6.2 X XTemperature 3.4.3 4.6.3 X -Vibration 3.4.4 4.6
49、.4 X -Shock 3.4.5 4.6.5 X -Pressureintegrity3.4.6 4.6.6 X X4.3 C onformance inspection . Conformance inspection shall be performed atthe place of manufacture. Conformance inspection shall consist of theexamination and tests specified in table I and shall be witnessed by aGovernment inspector.4.3.1 Lot . A lot shall consist of all snubbers of the same type,class, composition, and end connection manufactured at one time.4
