1、MIL-B-16961B 30 OCTOBER 1953 SUPERSEDING 26 February 1953 MIL-P-16961A (SHIPS) MILITARY SPECIFICATION PBRCELAIN ENAMEL COATING FOR STEEL MUFFLERS OF INTERNAL COMBUSTION ENGINES This speei$catioon has been approved by the Depart- ments of the Army, the Navy, and the Air Force 1. SCOPE 1.1 This specif
2、ication covers porcelain en- amel (nonmetallic inorganic fused) coating for exhaust mufflers of internal combustion engines. 2. APPLICABLE SPECIFICATIONS , STANDARDS, DRAWINGS, AND PUB- LICATIONS 2.1 The following specifications and stand- ards, of the issue in effect on date of invitation for bids,
3、 form a part of this specification: SPECIFICATIONS MILITARY MIL-6986-Electrodes (Mineral-Cov- ered, Low Hydrogen), Welding Medium and Alloy Steels (for Shipbuilding Ap- plication). MILM-i5337-Mufers, Exhaust, In- ternal Combustion Engines. MILS-161 13-8tee1, Plate, structural, Black (Uncoated) and Z
4、inc-Coated . (Galvanized). NAVY DEPARTMENT General Specifications for Inspection of Material, and Appendix II-Metals: Part A-Definitions and Tests. STANDARDS MILITARY MIESTD-O54ampIing Procedures and Tables for Inspection by Attributes, (Copies of specifications, standards, and drawings .required by
5、 contractors in connection with specific procurement functions should be obtained from the procuring agency or aa directed by the contracting officer.) 3. REQUIREMENTS 3.1 Qualification.-Porcelain enamel coat- ing provided under this specification for exhaust mufflers shall utilize the materials and
6、 processes approved on the basis of the qualification tests specied in section 4 (see 6.2). 3.2 Definitions. (a) Drain-line marking is defined as exces- sive accumulation of coating mate- rial as indicated by a deviation in coating thickness of 10 mils in X inch distance measured in any direction on
7、 the surface. (b) Component is defined as a subassembly attachable by bolting, (c) Exhibiitor is defined as an individual or orga.nization submitting samples for qualication tests authorized by the Government. (d) Muffler size is rated by the nominal OD pipe size of the exhaust inlet tube. 3.3 Mater
8、ial. 3.3.1 BasU metal.-The steel specified in the applicable mufTier specification and on appli- cable drawings and plans shall be of such enameling quality that, when fabricated into T-joint samples as shown on figure 1 and coated as specified in 4.2.3 and 4.4.1.2, it is capable of satisfactorily p
9、assing the thermal shock test specified in 4.5.1.1 (see 6.3). The steel plates sQ1ected for the fabrication of items to ba porce- lain enamel coated shall be free of rust or other surface blemish resulting in pockmarks not obliterated by sand blasting, and also free of deep scratches and-grip-mark i
10、ndentations. -. . f Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MILP-16961B 3.3.1.1 Steel for coating quali$cation.-Un- less otherwise authorized by the Bureau of Ships, tbe steel used in the fabrication of the T-joint specimens and simulated muf
11、fler sec- tions for coating qualification test shall con- form to the chemical composition requirement for type I, grade M of Specification MILS- 16113 (see 6.3.1). 3.3.2 Coating.-Unless otherwise specified in the contract or order, the muffler shall hhve a nonmetallic, inorganic, fused coating on a
12、ll interior and exterior surfaces. 3.4 Application.-The coating shall be ap- plied by a vitreous enameling process involving the deposition of materials by air spraying, dry dusting, slushing, dipping, or combination thereof. 3.5 Thickness.-The thickness of the coat- ing on the exhaust mufflers shal
13、l be from 0.004 to 0.016 inch (see 4.3). 3.6 Thermal shock resistance.-The coating shall withstand thermal shock when tested as specified in 4.5.1.1 and 4.5.2.1. 3.7 Completeness of coverage.-The coating on all visible surfaces of the exhaust mufflers shall be glassy smooth and conform to the approx
14、imate contour of the metal surfaces, free from drain-line markings, and perceptibly free of my discontinuity when inspected as specified in 4.3. 3.8 Marking.-Making shall be done by weld beading sufciently distinct to be readily identified after enameling. Each exhaust muffler shall be marked with t
15、he enameling lrms symbol in letters 2 to 4 inches in height on the outside surface of both ends before enameling. 4. SAMPLING, INSPECTION, AND TEST PROCEDURES 4.1 Qualification tests at a Government laboratory.-Qualication tests shall be con- ducted at a Government laboratory designated by the Burea
16、u of Ships. These tests shall consist of the tests specified in 4.5.2. 4.2 Sampling procedures. 4.2.1 Inspection lot.-An inspection lot shd consist of mufilers made of the same combina- tions of basis metal thickness and which have been coated by the same spraying, dusting, slushing, or dipping equi
17、pment and from tahe same mill batch of slip and fired under the same furnace operating conditions during a single enameling “run.” 4.2.2 Samplhg for and at the same time the meter indications shall be observed by the Government inspector. 4.3.1.1 Calibration of thickness gage.-When calibrating thick
18、ness gages, the Government inspector shall be assured that the nonmagnetic films (sheets or strips) of known thickness are placed on the surface of steel comparable in type and thickness to the steel on which the coating thickness is to be determined. If the coating procedure involves chemical treat
19、ment in an aqueous solution of a nickel salt, the thickness gage shall be calibrated against a blank representing the same steel used for fabricating the mufflers and subjected to the same chemical treatment, 4.3.2 Actim on the results of inspection.- Any sample muffler which has coating defects whi
20、ch expose the basis metal, drain-line mark- ings, or which at any point has coating thickness outside the limits of this specification, shall be rejected and if the number of such defective mufflers in my sample exceeds the acceptance number shorn in table I, for that sample, the lot which it repres
21、ents shall be rejected. Re- jected lots may be offered again for inspection provided the contractor has removed all non- conforming mufflers. The Government inspec- tor shall again select and inspect new samples from such resubmitted lots to verify compliance with this specication. 4.4 Test specimen
22、s. 4.4.1 Lot acceptance test specimens. 4.4.1.1 Thermal shock test specimens.-The T-joint specimens for thermal shock tests shall be fabricated according to the directions and dimensions shown ou figure 1 but the combina- tion of steel thicknesses employed shall be modxed to include samples from eac
23、h heat of steel and to represent the most abrupt change in section thickness obtained in the muffler. 4.4.1.2 Coating of lot acceptance test sped- mens.-The T-joint specimens shall be coated with the same mill batch(es) of slip and by the same procedure as employed for the mufflers. The coating shal
24、l be of a thickness equal to or greater than the maximum coating thickness of the mufers. However, the firing conditions shall be adjusted by taking into account differ- ences in mass-temperature effects between the T-joint specimen and the mufflers, so that the degree of maturing of the coating on
25、the test specimens shall be approximately the same as that on the mufer as indicated by similarity in color and gloss. The coating (and fabrica- tion where practicable) of these specimens shall be witnessed by the Government inspector. Whenever practicable, and at the discretion of the Government in
26、spector, one sample shall be processed with the first quarter, one specimen processed with the final quarter and the remain- ing one or more specimens distributed at ap- proximately equal intervals throughout the second and third quarters of the inspection lot being enameled. 4.4.2 Qwlli$cation 45 m
27、inutes dry and 15 minutes wet on an hourly cycle basis. The occurrence of coating defects that expose the basis metal shall be cause for rejection of the coating. a (c) 100 hours of “normal, wet” operation. 5. PREPARATION FOR DELIVERY 5.1 Mufers coated with porcelain enamel under this specifkation s
28、hall be prepared for shipment in accordance with Specication MIL-M-15337. 6. NOTES 6.1 Ordering data.-Procurement docu- ments should specify the title, number, and date of this specification. 6.2 In the procurement of products requir- ing qualification, the right is reserved to reject bids on produc
29、ts that have not been subjected to the required tests and found satisfactory for inclusion on the Military Qualified Products List. The attention of suppliers is called to this requirement, and manufacturers are urged to communicate with the Bureau of Ships, Navy Department, Washington 25, D. C., an
30、d arrange to have the products that they propose to off er to the Army, the Navy, or the Air Force, tested for qualification in order that they may be eligible to be awarded contracts or orders for the products covered by this specification. Information pertaining to qualification of prod- /.- - Pro
31、vided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-P-16961B fi 4 ii -I -4 THICK FIGURE 1.-Tee joint specimen (coupon) for thermal shack test. REQUIREMENTS
32、 1. Break all sharp edges. 2. Use type MIL-180 electrodes in accordance with Specification MIL-E-986. 3. “T” section shall be subjected to the following thermal shock test procedure: Heat IT section to a temperature of 650 F. Quench in water at a temperature of 70 to 90 F. Repeat until a total of 5
33、quenches has been made, Make series of 5 quenches from 800 P. Make series of 5 quenches from 900 F. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-REOUIREMENT 5 DETAIL OF CENTER SECTION E REQUIREMENT 5 IA. ASSEMBLY OF MUFFLER UNIT DETAIL OF INLET f3
34、 OUTLET SECTION FIGURE 2.-Mufler, exhaust, simulated. REQUIREMENTS 1. Use type MIL180 electrodes in accordance with Specification MILE986. 2. Welding slag and splatter shall be removed after fabricating. 3. Welds shall not be ground smooth over their full length, Short sections (2 to 4 inches in len
35、gth) of each weld shall be smooth ground. 4. All parts shall be supported during the ceramic coating firing operation so as to minimize sagging and dis- tortion. 5. Drill 8 holes, ?&ch, equally spaced. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
