Test Lab, NDT Weld Training Course Institute India Bangalore | Trinity NDT

Free Sample Radiography X-ray RT testing NDT Procedure

Disclaimer: The following sample Radiography X-ray testing RT procedure is meant for education purpose and should be revised to meet latest standard code requirements and actual NDT procedure requirements.


1.1:         This procedure describes the techniques and acceptance standard for Radiographic Examination of butt welds in steel (Carbon Steel, Alloy Steel, Stainless Steel etc.) up to 300 mm thickness, of Boilers (Drums, Headers, Pipelines etc.), Pressure Vessel and Heat Exchanger components. This procedure is also applicable for other materials like inconel and monel.

2.0:         REFERENCE

2.1          ASME Section I, V, VIII (Divn.1&2) /  2002 Addenda.

2.2          ANSI/ASME B 31.1 / 2001


3.1          The weld ripples or weld surface irregularities on both outside and inside (where accessible) shall be     removed by grinding or any other suitable process to such a degree that the resulting radiographic image due to irregularities cannot mask or  be confused with the image of any discontinuity.

3.2          The finished surface of all welded joints may be flush with the base material or may have reasonably uniform crowns, with reinforcement not to exceed that specified in Annexure I in each face.  If there is a question regarding the surface condition of the weld when interpreting radiographs, then radiographs shall be compared to the actual weld surface for determination of acceptability.


4.1          A lead letter ‘B’ of minimum 1.6 mm thick and 13 mm height shall be attached to the back of each film holder during each exposure to determine if back scatter is exposing the film.

4.2          Excessive back-scatter: If the image of the letter ‘B’ appears as lighter density than the back ground, it is an indication that protection against back scattering is insufficient and that additional Lead backing shall be used.


5.1          Each radiograph shall have a permanent identification traceable to the contract, component, weld  seam or part numbers as appropriate.

5.2          In addition BHEL symbol or manufacturer’s name and the date of the radiography shall be plainly and permanently included on the radiograph.

5.2.1       This identification system does not necessarily require that the information appear as radiographic images. These information shall not obscure the area of interest.

5.2.2       These images will appear on all the radiographs exposed individually and in minimum three radiographs if exposed by panoramic exposures.

5.3          For longitudinal welds in shells or in plate formed pipes the reference for the start of the segment shall be from one end of the weld. Sufficient over lap in the film shall be given to ensure 100% coverage in radiograph.

5.4          The entire longitudinal seam shall be divided, stamped and marked into number of segments.

5.5          Any geometric imperfection that requires rework by sur­face conditioning (and not by welding) after initial radiography, the affected area shall be blended smooth with adjoining surfaces by grinding to avoid sharp notches, crevices or corners.

5.6          The blended area shall be re-radiographed with letters suffixed G1, G2, G3 etc. to the original identification number to denote the number of times the weld has under­gone surface conditioning.

5.7          Letters R1, R2 etc will be suffixed to the original identification number, when radiographs are taken after repair by welding, to denote the number of times the weld has undergone repair.

5.8          Wherever retake has been performed, letters RT/(RT1), RT2 etc. will be suffixed to the original identification number.


6.1          Film:

6.1.1       The film used for radiography shall be as per SE 1815 and type ASTM System Class I or II. Generally the following brands of film shall be used. Other brands of films may be used subject to the approval of Head / NDT.

(a) Kodak-Industrex AA 400/T 200/M

(b) Agfa  Gevaert – Agfa D7/D5/D4

(c) Laser D7/D5/D4

6.1.2       The exposed films shall be processed as per procedure BHE: NDT: PB: RT: 14

6.2          Intensifying Screens:

6.2.1       Lead Screens of minimum thickness as listed below will be used on the front and back side of the film to improve the quality of the radiograph depending upon radiation energy selected.

X-rays                        upto  420 kV     0.02 to 0.25 mm

Ir.192                                                 0.10 mm

Co.60                                                 0.20 mm

4 MeV                                                0.25 mm

6.2.2       All intensifying screens shall be handled carefully to avoid dents, scratches, dirt or grease on the active surface, which might cause false indications.

6.3          Image Quality Indicator (IQI)

6.3.1       IQI shall be hole type and shall conform to SE 1025 and Table T.233.1 of ASME Section V.

6.4          Density Monitoring

6.4.1       Step wedge comparison filmstrip or a densitometer shall be used to judge the film density.

6.5          Facility for Film Viewing

6.5.1       The films shall be viewed in a room with subdued back­ground lighting of an intensity that will not cause troublesome reflections, shadows or glare on the radiograph.

6.5.2       Illuminators/Film viewers shall be used to view radiographs for interpretation. The illuminator shall provide a variable light source sufficient for the essential IQI hole to be visible for the density range specified and obtained in the radiograph.

7.0          CALIBRATION

7.1          Source Size

7.1.1       The technical manual or written statements of the equip­ment manufacturer or supplier’s publication documenting the actual or maximum source size or focal spot shall be acceptable as source size verification.

7.2          Step Wedge Film and Densitometer

7.2.1       The density of step wedge comparison films and densitometer calibration shall be verified by comparison with a standard step wedge film as per procedure BHE:NDT:RT:Calib:01.


8.1          The radiation energy ( X-rays energy up to 6 Mev, Iridium 192, Cobalt 60) employed for any Radiographic technique shall achieve the Density and IQI image requirements.


9.1          The direction of the central beam shall be centered on the area of interest whenever practical

10.0        GEOMETRIC UNSHARPNESS  (Source to Film Distance)

10.1        Film shall be kept in close contact with the object.

10.2        Table 1 may be used as a guideline for Geometric un-sharpness.

                                                TABLE – 1

Under 50.8 mm            0.51 mm
Over   50.8 to 76.2 mm             0.76 mm
Over   76.2 to 101.6mm1.02 mm
Greater than 101.6 mm            1.78 mm

Material thickness is the thickness on which the IQI is based.

10.3        Minimum source to film distance shall be kept such that the geometric unsharpness of the radiograph shall be kept as low as practical within the above range, but in any case shall not exceed 1.78 mm for Power Boiler components complying with ASME Section I or ANSI B 31.1.

10.4        Final acceptance of Radiographs shall be based on the achievement of required IQI sensitivity.


11.1        Radiographic technique

11.1.1     A single-wall exposure technique shall be used for radi­ography whenever practical. When it is not practical to use a single-wall technique, a double wall technique shall be used. An adequate number of exposures shall be made to demonstrate that the required coverage has been obtained. One exposure shall be taken for Double wall double image technique unless otherwise specified. Radiographic Exposure set up as given in annexure III shall be used as guide.  


12.1        The total length of the weld shall be divided into equal segments of length, approximately equal to 15 cms or 30 cms.  The segment where the spot is marked for examina­tion shall be radiographed with the corresponding segment numbers.

12.2        Single wall single image technique shall be used wherever possible:

12.3        One spot shall be examined on each vessel for each 15.2 metres increment of weld or fraction there of per welder or welding operator. However, for identical vessels each with less than 15.2 metres of weld, 15.2 metres increments weld may be represented by one spot examination.

12.4        Under condition where two or more welders or welding operators make weld layers in a joint, one spot may represent the work of all welders or welding operators.

12.5        Each spot examination shall be made as soon as practica­ble after completion of the increment of weld length to be examined.  The minimum length of spot radiography shall be 150 mm.


13.1        Location markers made of lead that are to appear as radiographic images on the film shall be placed on the part adjacent to the weld.  Their locations shall be marked and stamped on the surface of the part being radiographed in such a manner that an area of interest appearing on the radiograph will be accurately located. The location markers shall provide evidence on the film that complete coverage of the weld has been obtained.  Location markers shall not interfere with the interpreta­tion of the radiograph. Location markers shall be placed as given in figures (a) to (f) given in Annexures  IV.

13.2        Double wall Viewing

13.2.1     For double-wall viewing at least one location marker shall be placed on the source side surface adjacent to the weld for each radiograph – (Double Wall elliptical images with source off set for butt welds in Boiler Tubes).

14.0        SELECTION OF IQI

14.1        IQI shall be selected from either the same material group or grade as identified in SE – 1025 or from an material group or grade  with less radiation absorption than the material being radiographed.

14.1.1     The designated hole IQI with essential hole shall be as specified in Annexure II / Table-2. A smaller hole in a thicker IQI or a larger hole in a thinner  IQI   may  be  substituted  for  any section  thickness,  provided  equivalent  Hole type IQI  sensitivity as in Annexure II / Table-3 is maintained and all other requirements for radiography are met.

14.2        Weld with Reinforcement

14.2.1     The thickness on which the IQI is based is the nominal single wall thickness plus the estimated weld reinforcement not to exceed the maximum specified as in Annexure I.

14.2.2     Backing rings or strip are not to be considered as part of the thickness in IQI selection. The actual measurement of the weld reinforcement is not required.

14.3        Weld without reinforcement

14.3.1     The thickness on which the IQI is based is the nominal single wall thickness. Backing rings or strips are not to be considered as part of the weld thickness in IQI selection.

14.4        Welds joining dissimilar materials or welds with dissimi­lar filler metal

14.4.1     When the weld material has a radiation attenuation that differs from the base material, the IQI material selection shall be based on the weld metal and be in accordance with 14.1.  When the density limits of +30 % to -15% cannot be met with one IQI and the exceptional density area(s) is at the interface of the weld metal and the base metal, the material selection for the additional IQI shall be based on the base material and be in accordance with 14.1.

15.0        PLACEMENT OF IQI

15.1        Source Side IQI

15.1.1     Wherever possible, the IQI shall be placed on the source side of the part being examined.

15.2        Film Side IQI

15.2.1     Where inaccessibility prevents hand placing the IQI(s) on the source side, the IQI shall be placed on the film side in contact with the part being examined.  A lead letter ‘F’ shall be placed adjacent to the IQI(s) but shall not mask the essential hole

15.3        IQI Location for welds

15.3.1     The IQI will be generally placed adjacent to the weld. When placed on the weld, the identification numbers, the lead letter ‘F’ etc. shall not fall in the area of interest, except when geometric configuration makes it impractical.

15.4        IQI Location for materials other than welds

15.4.1     The IQI with the IQI identification, letter ‘F’ etc. may be placed in the area of interest.

16.0        NUMBER OF IQI

16.1        For components when one or more film holders are used for an exposure, at least one IQI image shall appear on each radiograph except as outlined below:

16.1.1     For circumferential welds in cylindrical and spherical components, where the source is placed on the axis of the weld for a single exposure (Panoramic Exposure), at least three IQI’s shall be spaced approximately 120° apart,

              (a) When the complete circumference is radiographed using one or more film holders, or;

              (b) When a section or sections of the circumfernce, where the length between the ends of the outermost sections span 240 or more degree is radiographed using one or more film holders.additional film locations may be required to obtain necessary IQI spacing.                                                               

16.1.2     For Cylindrical or Spherical components where the source is placed on the axis of the component for a single exposure, at least three IQI(s),with one placed at each end of the span of the circumference radiographed and one in the approximate centre of the span are re­quired under the following conditions:

              (a) When the section of the circumference, the length of which is greater than 120 degree and less than 240 degree is radiographed using just one film holder, or;

(b) When a section or sections of circumference, where the length between the ends of the

              outermost sections span less than 240 deg., is radiographed using more than one film holder.

16.1.3     In 16.1.1 and 16.1.2 above, where sections of longitudin­al welds adjoining the circumferential weld are radiographed simultaneously with circumferential weld, an additional IQI shall be placed on each longitudinal weld at the end of the section most remote from the junction with the circumferential weld being radiographed.

16.1.4     In spherical components, where other welds are radiographed simultaneously with the circumferential weld, one additional IQI shall be placed on each other weld.

16.2        When an array of components in a circle is radiographed, at least one IQI shall show on each component image.

16.3        In order to maintain the continuity of records involving subsequent exposures, all radiographs exhibiting IQI that qualify the techniques permitted in 16.1.1, 16.1.2, 16.1.3 or 16.1.4 shall be retained. Annexure V may be used as guide.

16.4        Multiple IQI

16.4.1     If the requirements of 17.2 are met by using more than one IQI, one shall be representative of the lightest area of interest and the other the darkest area of interest, the intervening densities on the radiograph shall be considered as having acceptable density.

16.5        Shims under IQI

16.5.1     A shim of material radiographically similar to the weld metal shall be placed between the part and the IQI, if needed, so that the radiographic density throughout the area of interest is within minus 15% from the radiographic density through the body of IQI

16.5.2     The shim dimensions shall exceed the IQI dimensions such that the outline of at least three side of the IQI image shall be visible in the radiograph.  

17.0        EVALUATION

17.1        Quality of radiographs

17.1.1     All radiographs should be free from mechanical, chemical or other blemishes such as fogging, processing defects to the extent that they do not mask or are not confused with the image of any discontinuity in the area of interest of the object being radiographed.

17.2        Radiographic density

17.2.1     The transmitted film density through the radiographic image of the body of the IQI  and the area of interest shall be 1.8 minimum for radiographs made with an X-ray source and 2.0 minimum for radiographic made with a gamma ray source. 

17.2.2     In both cases the maximum transmitted film density shall be 4.0. A tolerance of 0.05 in density is allowed for variation between the densitometer readings.

17.3        Density variation

17.3.1     If the density of radiograph any where through the area of interest varies by more than minus 15% or plus 30% rounded to the nearest 0.1 from the density through the body of the IQI within the minimum/maximum allowable density ranges specified in para 17.2.1, then an additional IQI shall be used for each exceptional area,one shall represent the lightest area and the other the darkest area of interest.

17.3.2     With shims: When shims are used, the +30% density re­striction of 17.3.1 above may be exceeded, provided the required IQI sensitivity is displayed and the density limitation of 17.2 are not exceeded.

17.4        IQI Sensitivity

17.4.1     Radiography shall be performed with a technique of sufficient sensitivity to display the hole IQI image and 2T hole which are the essential indications of the image quality of the radiographs.  The radiographs shall also display the identifying numbers and letters.  A thinner or thicker  IQI than listed in Annexure II (Table2) may be used if an equivalent IQI sensitivity as specified in Table III is obtained.


18.1        The following type of discontinuities shall be unaccept­able:

18.1.1     Any type of crack, zone of incomplete fusion or incomplete penetration.

18.1.2     Any other elongated indication on the radiograph whose length exceeds the following:

  1. 6  mm  for  thickness  up to  19 mm.
  2. 1/3  t  for  ‘t’  from  19  mm  to  57  mm.
  3. 19 mm for ‘t’ over 57 mm.

Where ‘t’ is the thickness of weld excluding any allow­able reinforcement. For a butt weld joining two members having different thickness at the weld, ‘t’ is the thinner of these two thicknesses. If a full penetration weld includes a fillet weld, the thickness of the throat of the fillet shall be included in ‘t’.

18.1.3     Any group of aligned indications that have an aggregate length greater than ‘t’ in a length of 12t except when the distance between successive indication exceeds 6L where ‘L’ is the longest indication in the group.

18.1.4     Rounded indications (whose length is less than three times the width) in excess of that shown as acceptable as in Appendix A 250 of ASME Section I or Appendix 4 of ASME Section VIII Division 1 or appendix 8 of ASME Section VIII Division 2 (all are identical). 

18.1.5     For circumferential joint in pipe, tube and headers, the thickness of the weld measured between the inside surface of the weld preparation and the outside surface of the pipe or tube shall not be less than the minimum thickness permitted by the applicable material specification for the particular size and thickness of the  pipe or tube used.

18.1.6     The contour of the concavity shall be smooth and the re­sulting thickness of the weld, including reinforcement, shall be at least equal to the required thickness of the thinner section. Root concavity shown without abrupt change in density is acceptable provided it is not greater than 2.5 mm in depth or 20% of thinner of the two sections, whichever is minimum for components fabricated as per Section I and 0.8 mm or 10% for components fabricated as per Section VIII. Comparable outside reinforcement shall be provided whenever acceptable root concavity is present.

18.2        Repaired area in a weld shall be re-radiographed using the same technique used for original radiography.


19.1        The following type of discontinuities are unacceptable :

19.1.1     Any zone of crack, lack of fusion or in-complete, penetration.

19.1.2     Slag inclusion or cavities whose length exceeds 2/3T to a maximum of 19 mm, where T is the thickness of the weld excluding any allowable reinforcement. For a butt weld joining two members having different thickness at the weld, ‘T’ is the thickness of the thinner of the two sections.

19.1.3     If several indications within the limitation given 19.1.2 above exists in a  line, the welds shall be judged accept­able if the sum of the larger dimensions of all such indications is not more the ‘T’ in a length of 6T (or proportionately, for radiographs shorter than 6T) and if the longest indications considered are separated by at least ‘3L’ of acceptable weld metal where L is the length of the longest indication. Any such indications shorter than 6 mm shall be acceptable for any plate thickness.

  1. Rounded indications (length less than three times the width) are not a factor in the acceptability of welds not required to be fully radiographed.

20.0        EVALUATION AND RETEST: (Spot Radiography)

20.1        When radiograph of one spot is found acceptable, the entire weld increment represented by this radiograph is acceptable.

20.2        If any spot is found defective, then two additional spots shall be radiographed from the same weld increment at location away from the original spot. If additional spots are found acceptable, then the entire weld increment represented by the three radiographs is acceptable. The defective area in the first radiograph will be removed, rewelded and re-radiographed as given above. 

20.3        If either of the two additional spots examined are found defective, then the entire increment of weld represented shall be radiographed and repaired or the entire weld shall be rejected.

20.4        If the entire weld is removed and rewelded based on the spot radiography result, the welded joint or weld repaired area shall be spot radiographically examined at one location in accordance with the procedure given above.


21.1        Personnel performing examination shall be qualified in accordance with BHE:NDT:G:CRT to at least one of the  following levels.

              1) Operator                            Minimum Level-1

              2) Film Evaluation                   Minimum Level  II


22.1        BHEL’s evaluation report shall be given in the format – 235-009 (Annexure IX) and shall be presented along with radiographs to External Inspector for approval.

23.0        STORAGE:

23.1        Radiographs of Products to ASME Code Sec. I, Sec. VIII Div.1 and Div.2 and Boiler drums:

23.1.1     A complete set of radiographs with proper identification shall be  preserved for a period of at least 5 years as in Quality Control Manual.

23.2        Radiographs of Other components:

23.2.1     Radiographs of header, pipe and tubular butt welds shall be retained and kept on file for a period of three years or till the final inspection, whichever is earlier.

23.2.2     Records such as registers and reports shall be maintained till the final inspection is completed.

24.0        SAFETY

24.1        Radiography shall be performed in accordance with all applicable safety requirements as specified in BHEL’s Safety Procedure BHE:NDT: G:SFT.

 Weld Thickness   (mm)Circumferential welds in Pipes & Tubes  ( mm)Other welds (mm) 
 Up to 
 Over 3.2 to 
 Over 4.8 to 
 Over13.0 to 
 Over 25.0 to 
 Over 51.0 to 76.0*4.0 
 Over 76.0 to 102.0*5.6 
 Over 102.0 to 127*6.4 
 Over 127*8.0 
*.  The greater of 6 mm or 1/8 times the width of the weld ( mm )
 Weld Thickness   (mm)Category B & C welds ( mm)Other welds (mm) 
 Up to 
 Over 2.4 to 
 Over 4.8 to 
 Over13.0 to 
 Over 25.0 to 
 Over 51.0 to 
 Over 76.0 to 
 Over 102.0 to 1276.06.0 
 Over 1278.08.0 
 Weld Thickness   (mm)Circumferential welds in Pipes & Tubes  ( mm)Other welds (mm) 
 Up to 
 Over 2.4 to 
 Over 4.8 to 
 Over12.7 to 
 Over 25.4 to 
 Over 50.8 to 
 Over 76.0 to 
 Over 102 to 1276.46.4 
 Over 1277.97.9 



Nominal Single Wall thickness Range (mm)Source side ————– Desgn.Film Side ———— Desgn.
Up to 6.4 mm1210
Over 6.4 thro’ 9.51512
Over 9.5 thro’ 12.71715
Over 12.7 thro’ 19.02017
Over 19.0 thro’ 25.42520
Over 25.4 thro’38.13025
Over 38.1 thro’ 50.83530
Over 50.8 thro’63.54035
Over 63.5 thro’ 101.65040
Over 101.6 thro’152.46050
Over 152.4 thro’203.28060
Over 203.2 thro’254.010080
Over 254.0 thro’304.8120100



Hole Type Designation 2T HoleEquivalent Hole Type Designation
1T Hole4T Hole
Pipe O.DExposure TechniqueRadiograph  ViewingSource-weld-film ArrangementIQILocation Marker Placement
End ViewSide ViewSelectionPlacement
AnySingle wallSingle wallTable 2Source side (15.1)Either side (13.0)
Film side (15.2)
AnySingle wallSingle wallTable 2Source side (15.1)Film side (13.0)
Film side (15.2)
AnySingle wallSingle wallTable 2Source side (15.1)Source side (13.0)
Film side (15.2)
Pipe O.DExposure TechniqueRadiograph  ViewingSource –weld-film ArrangementIQILocation Marker Placement
End ViewSide ViewSelectionPlacement
AnyDouble wall: at least 3 exposures 120° to each other for complete coverageSingle wallTable 2Source side (15.1)Film side (13.0)
Film side (15.2)
AnyDouble wall: at least 3 exposures 120° to each other for complete coverageSingle wallTable 2Source side (15.1)Film side (13.0)
Film side (15.2)
3 ½ in. or lessDouble wall: at least 2 exposures 90° to each other for complete coverageDouble wall (Ellipse): Read offset source side and film side imagesTable 2Source side (15.1)Either side (13.0)
Pipe O.DExposure TechniqueRadiograph  ViewingSource –weld-film ArrangementIQILocation Marker Placement
End ViewSide ViewSelectionPlacement
3 ½ in. or lessDouble wall: at least 3 exposures at 60° or 120° to each other for complete coverageDouble wall: Read Super imposed source side and film side imagesTable 2Source side (15.1)Either side (13.0)


Report No.:Date:Ref.:Stage of Test:
Description:Material:Dia.:                     mmThickness:          mm
W.O. No.:Drg. No.:DU No.:
Pb. Screen Front/Back              mmWelding Process:Weld  reinforcement:               mm
Source: X- Rays/ Ir. 192/ Co.60Source Size:                     mmExposure: KV:             mA / Ci.mts:
Source to Object distance:                              mmSource side of object to Film Distance:                mm
IQI: ASTM Hole / Wire type:Source side /Film sideSensitivity:                    Density:
Single/Double wall/Panoramic Technique  Single/ Double wall viewingMarkers:    Source / Film side
Film Manufacturer:  Agfa. / Kodak.Film Type / Designation :
No. of Radiographs ( Exposures ):No. of films in each cassette:Date of Evaluation:
Procedure & Acceptance : BHE:NDT:PB / SS / VV / NU / RT
Sl. No.Welder No.Radiograph No./ Joint No.Seg. No.FindingsDisposition ( Repair/Accept )
  ND = No Defect,  ICP = Incomplete Penetration,  LF = Lack of Fusion,  TI = Tungsten Inclusion,  BT = Burn Through,  UC = Undercut,  RC = Root Concavity,  EP = Excess Penetration,  PM = Process Mark,            Acc = Accept,  Rep = Repair