1、INCH-POUNDMIL-PRF-24758A(SH)24 September 2004 SUPERSEDING MIL-C-24758(SH) 05 August 1991 PERFORMANCE SPECIFICATION CONDUIT SYSTEMS, FLEXIBLE, WEATHERPROOF This specification is approved for use by the Department of the Navy and is available for use by all Departments and Agencies of the Department o
2、f Defense. 1. SCOPE 1.1 Scope. This specification covers the performance requirements for weatherproof flexible conduit systems (see 6.3.12) for use primarily in exposed areas (see 6.3.10) on U.S. Navy ships, to shield against electromagnetic (EM) radiation from own-ship transmitters and emissions e
3、xternal to the ship, electromagnetic pulse (EMP) (see 6.3.8) events, and to minimize corrosion (see 6.3.6) while being field repairable to reduce maintenance. 1.2 Classification. Classification on conduit sizes is as follows: Nominal ID (inches/metric) Minimum ID (inches/metric) Maximum OD (inches/m
4、etric) .25 in (6 mm) .245 in (6.223 mm) .58 in (14.732 mm) .50 in (13 mm) .495 in (12.573 mm) .85 in (21.59 mm) .75 in (19 mm) .745 in (18.923 mm) 1.10 in (27.94 mm) 1.00 in (25 mm) .995 in (25.273 mm) 1.41 in (35.814 mm) 1.25 in (32 mm) 1.245 in (31.623 mm) 1.66 in (42.164 mm) 1.50 in (38 mm) 1.495
5、 in (37.973 mm) 1.91 in (48.514 mm) 2.00 in (50 mm) 1.995 in (50.673 mm) 2.44 in (61.976 mm) 2.50 in (63 mm) 2.495 in (63.373 mm) 2.94 in (74.676 mm) Beneficial comments, recommendations, additions, deletions, clarifications, etc. and any data that may improve this document should be sent to: Comman
6、der, Naval Sea Systems Command, ATTN: SEA 05Q, 1333 Isaac Hull Avenue, SE, Stop 5160, Washington Navy Yard DC 20376-5160 or emailed to commandstandardsnavsea.navy.mil, with the subject line “Document Comment”. Since contact information can change, you may want to verify the currency of this address
7、information using the ASSIST Online database at www.dodssp.daps.mil. AMSC N/A FSC 5975 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-PRF-24758A(SH) 1.3 Part or identifying number (PIN). PINs to be used for conduits acquired to this specificatio
8、n are created as follows: M 24758 - X Prefix for Military Specification Specification number Size (see code below) Nominal ID (in/mm) PIN Code .25 in (6 mm) A .50 in (13 mm) B .75 in (19 mm) C 1.00 in (25 mm) D 1.25 in (32 mm) E 1.50 in (38 mm) F 2.00 in (50 mm) G 2.50 in (63 mm) H 2. APPLICABLE DOC
9、UMENTS 2.1 General. The documents listed in this section are specified in sections 3, 4, or 5 of this specification. This section does not include documents cited in other sections of this specification or recommended for additional information or as examples. While every effort has been made to ens
10、ure the completeness of this list, document users are cautioned that they meet all specified requirements cited in sections 3, 4, or 5 of this specification, whether or not they are listed. 2.2 Government documents. 2.2.1 Specifications, standards, and handbooks. The following specifications, standa
11、rds, and handbooks form a part of this document to the extent specified herein. Unless otherwise specified, the issues of these documents are those cited in the solicitation or contract. DEPARTMENT OF DEFENSE SPECIFICATIONS MIL-S-901 - Shock Tests, H.I. (High Impact) Shipboard Machinery, Equipment,
12、and Systems, Requirements For DEPARTMENT OF DEFENSE STANDARDS MIL-STD-167-1 - Mechanical Vibrations of Shipboard Equipment (Type I - Environmental and Type II - Internally Excited) (Copies of these documents are available online at http:/assist.daps.dla.mil/quicksearch/ or www.dodssp.daps.mil or fro
13、m the Standardization Document Order Desk, 700 Robbins Avenue, Bldg. 4D, Philadelphia, PA 19111-5094.) 2.3 Non-Government publications. The following documents form a part of this document to the extent specified herein. Unless otherwise specified, the issues of these documents are those cited in th
14、e solicitation or contract. ASTM INTERNATIONAL B117 - Standard Practice for Operating Salt Spray (Fog) Apparatus (DoD adopted) (Copies of this document are available online at www.astm.org or from ASTM International, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959.) 2Provided by IHSNot for R
15、esaleNo reproduction or networking permitted without license from IHS-,-,-MIL-PRF-24758A(SH) INTERNATIONAL ELECTROTECHNICAL COMMISSION (IEC) 60068-2-5 - Environmental Testing - Part 2: Tests. Test Sa: Simulated Solar Radiation at Ground Level 60096-1-am2 - Radio Frequency Cables. Part 1: General Req
16、uirements and Measuring Methods - Amendment No. 2 60423 - Conduits for Electrical Purposes - Outside Diameters of Conduits for Electrical Installations and Threads for Conduits and Fittings 60529 - Degrees of Protection Provided by Enclosures (IP Code) 60614-1 - Conduits for Electrical Installations
17、 Specification - Part 1: General Requirements 60614-2-5 - Specifications for Conduits for Electrical Installations - Part 2: Particular Specifications for Conduits - Section 5: Flexible Conduits 60695-2-4/1 - Fire Hazard Testing - Part 2: Test Methods - Section 4/Sheet 1: 1 kW Nominal Pre-Mixed Test
18、 Flame and Guidance 60754-2 - Test on Gases Evolved During Combustion of Electric Cables - Part 2: Determination of Degree of Acidity of Gases Evolved During the Combustion of Materials Taken from Electric Cables by Measuring pH and Conductivity 61035-1 - Specification for Conduit Fittings for Elect
19、rical Installations - Part 1: General Requirements 61035-2-3 - Specification for Conduit Fittings for Electrical Installations - Part 2: Particular Specifications - Section 3: Fittings for Flexible Conduits of Metal, Insulating or Composite Materials and for Pliable Conduits of Metal or Composite Ma
20、terials (Copies of these documents are available online at www.iec.ch or from IEC Central Office, 3 rue de Varemb, P.O. Box 131, CH 1211 Geneva 20, Switzerland.) 2.4 Order of precedence. In the event of a conflict between the text of this document and the references cited herein, the text of this do
21、cument takes precedence. Nothing in this document, however, supersedes applicable laws and regulations unless a specific exemption has been obtained. 3. REQUIREMENTS 3.1 Measurement units. English units shall be used to the maximum extent possible followed by the metric equivalent. 3.2 First article
22、. When specified (see 6.2), a sample shall be subjected to first article inspection in accordance with 4.2. 3.3 Materials. Materials shall be used which will enable the assemblies to meet the performance requirements of this specification. The external finish of fittings and constituent parts shall
23、be dull and non-reflective. The external finish on the conduit shall be paintable or ship gray in color. Materials used for end fittings shall be interchangeable with like components and mate to existing hardware currently employed aboard U.S. Navy ships. 3.3.1 Recycled, recovered, or environmentall
24、y preferable materials. Recycled, recovered, or environmentally preferable materials should be used to the maximum extent possible provided that the material meets or exceeds the operational and maintenance requirements, and promotes economically advantageous life cycle costs. 3Provided by IHSNot fo
25、r ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-PRF-24758A(SH) 3.4 Environmental conditions. Flexible conduits (see 6.3.12), conduit fittings, and constituent parts supplied under this specification shall meet the following environmental conditions (see 6.3.9). 3.4.1
26、 Temperature range. -40F to +257 F (-40 C to +125 C). 3.4.2 Relative humidity. 10 to 100%. 3.4.3 Solar radiation. 112047 watts per meter squared (W/m2). 3.4.4 Shipboard environmental conditions. In addition, the equipment supplied shall be able to withstand salt fog, greenwater loading (see 6.3.13),
27、 stack gas and external influences (see 6.3.11), normal wear and tear evolutions such as line and hose handling evolutions, fresh/saltwater washdowns, shipboard shock, and jet blast effects. Equipment applications require satisfactory performance under weapon effects including shock (see 6.3.16) and
28、 EMP effects. 3.5 Flexible conduit and fitting size. 3.5.1 Flexible conduit size. Flexible conduit size shall be specified (see 6.2) by nominal ID in accordance with Table I to accommodate Naval shipboard external use applications. For conduits normally provided with a protective coating, the test f
29、or measuring the outside diameter will be conducted after the application of the protective coating. Dimensions and tolerances shall be interpreted as specified in Table I. TABLE I. Conduit sizes. Nominal ID (inches/metric) Minimum ID (inches/metric) Maximum OD (inches/metric) .25 in (6 mm) .245 in
30、(6.223 mm) .58 in (14.732 mm) .50 in (13 mm) .495 in (12.573 mm) .85 in (21.59 mm) .75 in (19 mm) .745 in (18.923 mm) 1.10 in (27.94 mm) 1.00 in (25 mm) .995 in (25.273 mm) 1.41 in (35.814 mm) 1.25 in (32 mm) 1.245 in (31.623 mm) 1.66 in (42.164 mm) 1.50 in (38 mm) 1.495 in (37.973 mm) 1.91 in (48.5
31、14 mm) 2.00 in (50 mm) 1.995 in (50.673 mm) 2.44 in (61.976 mm) 2.50 in (63 mm) 2.495 in (63.373 mm) 2.94 in (74.676 mm) 3.5.2 Conduit fittings size. Conduit fittings shall be specified (see 6.2) by nominal ID of flexible conduit in which they are to be installed. Conduit entries in conduit fittings
32、 shall be suitable for flexible conduits that will accommodate those conduit sizes listed in Table I. Means shall be provided within the conduit system for securing the conduit to the conduit fitting and internally will provide for protection for the conductors or cables. 3.5.3 Interchangeability. T
33、he threads of conduit fittings and constituent parts shall be compatible with standard shipboard interfaces. 3.6 Conduit system. Conduits, conduit fittings, and constituent parts shall provide for installation, removal, inspection, and reinstallation of assemblies between fixed threaded fittings. Th
34、e conduit system shall have at least one swivel fitting (see 6.3.17) attached, or other means of securing the conduit to the fitting without causing or requiring the conduit to rotate during the fabrication. The conduit system shall provide protection for the conductors and cables contained therein.
35、 4Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-PRF-24758A(SH) 3.7 Conduit/conduit fitting integrity. Conduits when bent or compressed, exposed to vibrations (see 6.3.19), or when exposed to extreme specified temperatures, shall maintain the fo
36、llowing properties. 3.7.1 Compression. Conduits, when bent or banded, shall not compress by more than 10% of the conduit initial inside diameter (ID) when subjected to a compression force of 168.60 pounds (lbs) (750 newtons (N). 3.7.2 Impact. The conduit system shall maintain performance requirement
37、s for electrical, electromagnetic, and weatherproofing properties when subjected to 14.75 ft/lbs (20 joules) of blunt impact energy with a fall height of 12 inches plus or minus .25 inches (304mm plus or minus 6 mm). 3.7.3 Vibration. The conduit system shall remain intact and the end fittings are to
38、 remain torqued to the manufacturers specification when tested in accordance with paragraph 4.7.3. 3.7.4 Tensile strength. A complete conduit system with two terminating fittings shall show no damage nor have fittings become loosened when subjected to a tensile force of 224.80 lbs (1000 N). 3.7.5 Fl
39、exing. A conduit system with a terminating fitting, assembled according to the manufacturers instructions, shall have no visible structural damage after two hundred flexings of 120 degrees, at the rate of 20 flexings per minute (min) at each of the temperature limits: -40 F (-40 C) to +257 F (+125 C
40、). (see 3.4.1) 120 is understood to mean 60 each side of the longitudinal axis. 3.7.6 Resistance to heat. The conduit shall demonstrate resistance to heat at 257 F (125 C) and not be depressed under load for the relevant conduit. Conduit fittings and constituent parts shall demonstrate resistance to
41、 heat at 257 F (125 C) and not dimple under load. 3.7.7 Resistance to flame-propagation. Conduits shall demonstrate resistance to flame-propagation. 3.7.8 Acid gas emission. Conduit systems shall be halogen free (see 6.3.14). The level of acid gas evolved by conduits calculated as hydrochloric shall
42、 be not greater than .0001764 ounce (oz) (5 milligrams (mg) of hydrochloric acid per gram of sample. 3.7.9 Shock. Conduit systems shall maintain performance requirements for electrical/electromagnetic properties and watertight integrity when subjected to nine hammer blows from a medium weight shock
43、machine. 3.8 Weatherproofing. The conduit system shall be inherently weatherproof from end fitting to end fitting. The conduit system, with the ends of both terminating fittings plugged, shall allow no ingress of water when subjected to a water jet of 26.42 gallon (100 liters)/min 5%, from a .49-inc
44、h (12.5-mm) diameter nozzle at a distance of 8.20 to 9.84 feet (2.5 to 3 meters) for 3 minutes. 3.9 External corrosion. Conduit systems shall be constructed of materials that provide external corrosion protection. Conduit systems shall show no evidence of corrosion when subjected to a cyclic sulfur
45、dioxide/salt fog (SO2/NaCl) test. 3.9.1 Corrosion and polluting substances. Conduit systems shall demonstrate a high degree of protection against corrosion, both outside and inside, when flexed to the minimum bend radius of 8 times the conduits outside diameter (OD). 3.9.2 Solar radiation. The condu
46、it system shall not degrade in electrical or mechanical performance due to exposure to 10 cycles of solar radiation. The conduit shall be resistant to solar radiation as defined in 3.4.3. 3.10 EM signal attenuation. EM signal attenuation over a frequency range of 100 KHz to 600 MHz for a conduit sys
47、tem shall not exceed a surface transfer impedance of 100 milliohms per meter. 5Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-PRF-24758A(SH) 3 3.11 Marking. Conduits shall be marked with: a. Name of the manufacturer, responsible vendor, trademar
48、k, or other identifying symbol. b. Classification codes in accordance with applicable IEC 60614-1 Annex A. c. Any other mark or symbol required by IEC 60614-2-5 Annex A. d. “Halogen Free” shall appear on all conduits. The markings on conduits and conduit fittings shall be legibly and permanently mar
49、ked on the material, and located as described in 3.11.1 and 3.11.2 to insure readability when the fittings are installed. 3.11.1 Flexible conduit marking. The weatherproof jackets of flexible conduits shall be paintable or surface ship gray in color. If a conduit is marked with a type reference and/or a size, these markings are placed before the identification of the manufacturer or responsible vendor. Marking of classification codes shall be in accordance w
