Type of Test	Symbol
Acoustical test	AET
Electromagnetic	ET
Leak	LT
Magnetic particle	MT
Neutron radiographic	NRT
Penetrant	PT
Proof	PRT
Radiographic	RT
Ultrasonic	UT
Visual	VT

TABLE 25.1 ■ Nondestructive examination symbols. Note: Each symbol ends with the letter “T.”

Nondestructive testing symbols are used to indicate the type of test or tests the welds will be subjected to when completed. Abbreviations for the common examinations are shown in Table 25.1.

The examination symbol consists of a reference line, arrow, and tail. Elements added to this symbol are exami­nation symbols, basic weld symbols, the examine-all - around symbol (similar to the weld-all-around symbol), the examine-in-field symbol (similar to the field-weld symbol), number of tests, length or percentage of the part to be exam­ined, specifications or references, and direction of radiation for radiographic tests, Figure 25.1. The arrow side, other side, and both sides significance described for the basic welding symbol also applies to the nondestructive testing symbol.

As indicated in Figure 25.1, examination symbols may be applied in three locations with respect to the reference line of the nondestructive welding symbol—on the arrow side, on the other side, or centered on the reference line. When a both sides significance is desired, the examination symbol

NUMBER OF EXAMINATIONS REQUIRED, ENCLOSED IN PARENTHESES (LOCATED ON OTHER SIDE OR ARROW SIDE)

(N) у SYMBOL 'SYMBOL SYMBOL

POSSIBLE LOCATIONS OF SYMBOLS (TYPE OF EXAMINATION)

LENGTH OF SECTION TO BE EXAMINED

EXAMINE IN FIELD

EXAMINE-ALL- AROUND

-WHEN CENTERED, HAS NO ARROW SIDE, OTHER SIDE SIGNIFICANCE

■ OTHER SIDE

-LOCATION OF SPECIFICATION OR OTHER REFERENCE

-WHEN SYMBOL IS PLACED ON BOTH SIDES OF REFERENCE LINE, IT HAS A BOTH SIDES SIGNIFICANCE

-ARROW SIDE

FIGURE 25.1 ■ Nondestructive examination symbol.

is applied to both sides of the reference line. When an arrow side or other side significance is not applicable, the examination symbol is centered on the reference line, Figure 25.2.

EXAMINATION TO BE MADE ON OTHER SIDE ET

AET

EXAMINATION TO BE MADE ON ARROW SIDE

hen multiple tests are required, they are indicated by combining the test symbols, as shown in Figure 25.3. Note that test symbols having an arrow side or other side signifi­cance may be combined with a test symbol centered on the reference line (no arrow side or other side significance).

• AET -

EXAMINATION TO BE MADE NOT HAVING AN ARROW OR OTHERy SIDE SIGNIFICANCE

Test symbols are frequently used in combi­nation with basic weld symbols. When this is the case, they are applied to a testing symbol with multiple reference lines, Figure 25.4.

FIGURE 25.2 ■ Locations of test symbols.

For testing purposes, the dimensions applied to a testing symbol are: (1) length of section to be tested, or (2) percentage of section to be tested, and (3) angle of radia­tion when a radiographic test is required.

Length or percentage is shown only when a partial section is to be tested. Note that when length or percentage dimensions are used, they are located to the right of the test symbol, Figure 25.5 and Figure 25.6.

Dimensions may also be added as shown in Figure 25.7 to locate the particular length of weld to be tested.

When a percentage dimension is used to indicate that only a partial section of the weld is to be tested, the procedure for select­ing the location of the test is described in the specifications or by a note on the drawing,

Figure 25.8.

In cases where testing applies to an area of a part, several dimensioning techniques are used. For a plane area, the section of the

area to be examined is shown circumscribed FIGURE 25.3 ■ Combining examination symbols.

FIGURE 25.4 ■ Combining basic weld and non­destructive examination symbols through the use of multiple reference lines.

FIGURE 25.5 ■ Application of length dimension for examining a partial section.

RT 50% FIGURE 25.6 ■ Application of percentage dimension for examining a partial section of weld.

FIGURE 25.7 ■ Application of dimensions for indicating length of welded section to be examined.

FIGURE 25.9 ■ Method of indicating a section of a plane area to be examined.

FIGURE 25.8 ■ Percentage method of indicating extent of a welded section to be examined.

by broken lines with circles at the connecting points, Figure 25.9. Location and size dimensions are applied as needed. The appropriate examination symbol is added with the arrow touching any point of the perimeter of the area to be examined, Figure 25.9.

To indicate that an area of revolution is to be examined, the examine-all-around symbol is applied, with or without a length dimension, depending upon the extent of the area to be examined, Figure 25.10.

When a length dimension is applied to the testing symbol with an examine-all-around symbol, it signi­fies that only a particular length of the area of revolution is to be examined, Figure 25.11.

For pressure vessels or pipe, an acous­tic emission examination may be indicated, Figure 25.12. When such an examination is indicated, it generally applies to all or most of the component. Therefore, no dimension is shown with the symbol. The locations of the sensors for making the examination are not shown. This permits a random selection of locations for making the examination.

TEST-ALL-AROUND SYMBOL

—1

MT

EXAMINATION SYMBOL WITHOUT A LENGTH DIMENSION INDICATES ENTIRE LENGTH OF THE BORE IS TO BE EXAMINED

FIGURE 25.10 ■ Application of the examine-all-around symbol for an area of revolution to be examined.

For radiographic inspections, the degree of angle for executing the inspection is included on the drawing, Figure 25.13(a). The angle dimension is applied between an extension line and an extension of the arrow of the welding symbol resembling an asterisk is located at the end of the arrow extension line. When an angle dimension is not shown, it implies that the angle of radiation is 90°, Figure 25.13(b).

FIGURE 25.11 ■ Application of examination-all-around symbol and length dimension for an area of revolution.

The remaining element applied to the nondestructive examination symbol is the number of examinations to be made. This is indicated by placing a numerical value in parentheses above or below the exam­ination symbol, Figure 25.14. When the examination symbol is located on the arrow side, the figure is placed below the symbol; when the examination symbol is on the other side, it is placed above the examina­tion symbol. If the symbol is centered on the reference line, the indication for the number of examinations is placed on either

ALTHOUGH NOT INDICATED BY A DIMENSION, ANGLE OF RADIATION IS 90° SINCE THE SYMBOL APPEARS TO BE PERPENDICULAR TO WELD TO BE EXAMINED

FIGURE 25.13 ■ Application of direction of radia­tion dimension for radiographic examinations.

NUMBER OF - EXAMINATIONS REQUIRED, NO ARROW SIDE OR OTHER 4 SIDE SIGNIFICANCE

NRT SIGNIFIES NEUTRON (b) RADIOGRAPHIC TEST

FIGURE 25.14 ■ Application of figure to examination symbol to indicate the number of tests required.

NUMBER OF EXAMINATIONS REQUIRED, ARROW SIDE

NUMBER OF EXAMINATIONS REQUIRED, OTHER SIDE

(4) RT

PT (6)

(3)

side of the symbol. In determining locations for the examination, they are taken at random along the joint or area of the part to which the symbol is applied.

U. S. Customary (Inch) Metric (Millimeters)

Dimensioning practices applied to the nondestructive examination symbol exclude dual dimensioning (the use of both U. S. Customary and metric dimensions). When dimensions in both units are necessary, a table of conversions is added to the drawing. Examples of conversion tables are shown in Table 25.2 and may also be found in the Appendices.

Electrode Sizes	Fillet Sizes
in.	mm	in.	mm
0.030	0.76	1/8	3
0.035	0.89	5/32	4
0.040	1.02	3/16	5
0.045	1.14	1/4	6
1/16	1.59	S/16	8
5/б4	1.98	3/8	10
3/32	2.38	7/l6	11
1/8	3.18	1/2	13
5/32	3.97	5/8	16
3/16	4.76	3/4	19
1/4	6.35 ^	7/8	22
t		1	25

TABLE 25.2 ■ Conversion tables.

UNIT 25: REVIEW

1. Describe nondestructive examinations and their locations indicated by the following symbols.

2. Give the significance of each element shown on the following nondestructive examination symbol.

LT

f. AET

3. Give the significance of all of the elements applied to the examination symbols shown on the drawings that follow.

UT

c.

RT

60