MIL-STD-202H.pdf - 第159页

MI L - S TD - 202 - 20 9 M E TH O D 20 8 RA DI O G RA P HI C I NS P E C T I O N 1. SCOPE 1.1 P urpose . Radiog r aph i c i ns pec t i on i s gener al l y a non des t r uc t i v e ( s ee 1 . 2 ) m et h od f or detect ing …

MIL-STD-202-209

CONTENTS

PARAGRAPH PAGE

FOREWORD…………………………………………………………. ii

1. SCOPE 1

1.1 Purpose………………………………………….……..…………. 1

1.2 Precautions…………………………………………………….…. 1

2. APPLICABLE DOCUMENTS 1

3. DEFINTIONS 1

4. GENERAL REQUIREMENTS 1

4.1 Apparatus and materials.……………………….…...…………. 1

4.1.1 Radiographic equipment.………………….……………………. 1

4.1.2 Film holder………………………………….……………………. 1

4.1.3 Image-quality indicator………………………………………….. 1

4.1.4 Film………………………………………………………………... 1

4.2 Nonfilm techniques.…...………………..…………….…………. 1

4.3 Personnel safety precautions..…………………………………. 1

4.4 Procedure…………………………………………………………. 2

4.5 Positioning of specimen…………………………………………. 2

4.6 Exposure parameters……………………………………………. 2

4.7 Intensifying screens…………………………………..…………. 2

4.8 Identification of radiographs..………………………..…………. 2

4.9 Marking of radiographed specimens. …………………………. 2

5. DETAILED REQUIREMENTS 2

5.1 Evaluations………….………………………………………….… 2

5.2 Summary……………………………………………………….… 3

6. NOTES 3

6.1 Supersession data………………………………………………. 3

iii

北测（上海）电子科技有限公司

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MIL-STD-202-209

METHOD 208

RADIOGRAPHIC INSPECTION

1. SCOPE

1.1 Purpose. Radiographic inspection is generally a nondestructive (see 1.2) method for detecting internal

physical defects in small component parts which are not otherwise visible. Radiographic techniques are intended to

reveal such flaws as improper positioning of elements, voids in encapsulating or potting compounds, inhomogeneities

in materials, presence of foreign materials, broken elements, etc.

1.2 Precautions. Radiographic inspection may be performed on most parts; however, radiation may cause

changes in electrical behavior of some materials.

2. APPLICABLE DOCUMENTS

This section not applicable to this standard.

3. DEFINTIONS

This section not applicable to this standard.

4. GENERAL REQUIREMENTS

4.1. Apparatus and materials.

4.1.1 Radiographic equipment. The radiographic equipment used shall be capable of producing the required

radiographic quality as specified in the individual specification. When using X-ray equipment, X-ray tubes with small

effective focal-spot sizes and low inherent filtration are recommended.

4.1.2 Film holder. A lightproof film holder of low inherent filtration to radiation is recommended when using

voltages of 50 kilovolts. A lead backing plate should be used behind the film holder to minimize fogging due to

secondary back-scatter.

4.1.3 Image-quality indicator. The image-quality indicators used to indicate radiographic sensitivity shall be as

specified in the individual specification. The sensitivity is the combined measure of the definition and contrast of the

radiograph and should be such that the maximum allowable defect shall be shown. The image-quality indicator may

be made from a sample part of the same type as the part being radiographed and should contain either an actual or

simulated defect which is at least 10 percent smaller than the smallest defect to be detected.

4.1.4 Film. The film shall be compatible with the sensitivity required in 4.1.1. In general, finer detail is achieved by

the use of finer grain films with lower exposure indexes. If extreme magnification techniques are required, the use of

single emulsion films is recommended.

4.2 Nonfilm techniques. Nonfilm techniques may be used if required sensitivity levels, and records (when

specified) can be obtained (see 4.1.1).

4.3 Personnel safety precautions. The safety precautions described in National Bureau of Standards (NBS)

Handbook 76 - X-Ray Protection; NBS Handbook 73 - Protection Against Radiations From Sealed Gamma Sources;

Atomic Energy Commission Book Title 10, Part 20 - Standard for Protection Against Radiation, Part 30 - Licensing of

By-product Material, Part 31 - Radiation Safety Requirements for Radiographic Operations, shall be complied with

when applicable.

北测（上海）电子科技有限公司

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MIL-STD-202-209

4.4. Procedure.

4.5 Positioning of specimen. The leaded film holder is backed up by the lead plate (see 4.1.2), and the specimen

to be radiographed shall be placed in the position or positions specified in the individual specification.

4.6 Exposure parameters. The following exposure parameters may be varied to obtain the radiographic quality

specified in 4.1.1:

a. Source - film distance.

b. Kilovoltage or type of isotope.

c. Milliamperage or source strength of isotope.

d. Exposure time.

e. Film speed.

f. Intensifying screen.

The detail sensitivity is affected by the following:

a. Focal spot size.

b. Film grain size.

c. Nature of the specimen.

d. Placement of the specimen.

The above factors should be taken into consideration when determining the exposure parameters.

4.7 Intensifying screens. In general, metallic intensifying screens should be used at X-ray tube voltages above 125

kilovolts to minimize fogging and for intensifying effects.

4.8 Identification of radiographs. Suitable means shall be employed to identify individual specimens on the

radiographic record.

4.9 Marking of radiographed specimens. If required, suitable marking shall be specified in the individual

specification indicating that specimens have been inspected radiographically.

5. DETAILED REQUIREMENTS

5.1 Evaluations. The final image shall be examined with suitable viewing equipment, which may include

magnification, to determine such defects as improper positioning of elements, voids in encapsulating or potting

compounds; inhomogeneities in materials; presence of foreign materials; broken elements; and other defects as

specified in the individual specification.

北测（上海）电子科技有限公司

联系方式：xuyj@beice-sh.com 13917165676