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Reg. 561 b

Test for Class I boilers

 

iv)

Impact tests:- Two rectangular specimens shall be cut out transversely to the welded joint and they shall conform to the dimensions shown in Figure XII/62.

One specimen shall have the notch cut at the middle of the outer surface of the weld, and the other at the middle of the inner surface of the weld.

The tests shall show a minimum Izod impact test value of 20 foot pounds, the test being carried out at a temperature between 50°C (122°F) and 100°C (212°F).

v) Macro and Micro examinations: A specimen of the full thickness of the plate and not less than 13 millimetres wide shall be provided from each set of test plates for the purpose of macro and micro examinations.

Microetching of a complete cross-section of the weld including the heat affected zone, should show satisfactory penetration, fusion  and absence of significant  inclusions or other defects. 

Should there be any doubts as to the condition of the weld as shown by macro-etching, the area concerned is to be microscopically examined for defect investigation. 

vi) Additional Tests before rejection: Should any of the test specimens taken in accordance with this Regulation fail to meet the specified requirements, retests shall be allowed for each specimen that fails as follows:-

Where any result of the tensile test is not less than 90% of the specified figures one retest shall be made. Where any result falls below 90%, two retests shall be made.

Where a bend specimen fails to meet the specified requirements, two retests shall be made.

If an impact test fails to meet the specified requirements, two retests shall be taken from the test plate, one on each side of the final specimen and separate from it by not more than 5 millimetres.

If it be found there is insufficient metal to permit the preparation of specimens for retest from the remainder of the test plate from which the original specimen was taken, the specimen for retest may be cut from the test plate relating to the opposite end of the same longitudinal seam.

Should any of the additional tests fail to meet the specified requirements the welded seams represented by these tests shall be rejected.
vii) Specimens after test: If required the specimens after test shall be at the disposal of the Inspecting Authority for examination.
viii) Radiographic examinations: Every portion of the longitudinal and circumferential butt-welded seams of the shell of the boiler shall be subjected to radiographic or ultrasonic examination. Where ultrasonic examination is used, it shall be demonstrated to the satisfaction of the Inspecting Authority that the equipment and the technique used are satisfactory, the manufacturer shall ensure that the operator employed is competent to use the equipment, apply the technique and interpret the results of the examination. The methods employed in obtaining the radiographs shall be such as to show clearly differences equal to 2% of the thickness at the welded joints. To determines whether this result is being attained, an indicator of approved form which includes a portion equivalent to not more than 2% of the joint thickness shall be placed in the vicinity of the weld so as to make a record on each radiograph. Each section of every weld shall be marked so that the radiographs can be easily corrected to the particular part of the seam represented.

The examination shall be made from the original films and the acceptability of the welds shall be decided by the Inspecting Authority. The welds deemed unsatisfactory shall be rejected or dealt with under the condition of regulation 560 and can be radiographed again. The films shall be retained by the manufacturer for a reasonable period for reference and be available to the Inspecting Authority, if required.

NOTE:-
(1) Magnetic particle flaw detection:- Magnetic methods of flaw detection shall be employed wherever possible for ferritic steel.

(2) Dye-penetrant flaw detection:- Dye penetrant or equivalent methods of flaw detection shall be employed for Austenetic or other non-magnetic steel

(3)  All butt welded joints shall be subjected to non-destructive examination by radiographic, radioscopy or other approved methods such as ultrasonic testing, magnetic particle inspection or liquid dye penetrant inspection.  When radioscopic examination is to be performed in lieu of radiography on welded components, the following requirements shall be met, namely:- 

(a)   A written procedure shall be submitted for approval to the Inspecting Authority which shall contain the following:

(i)                 material and the thickness range;

(ii)               equipment qualifications;

(iii)             test object scan plan;

(iv)             radioscopic parameters;

(v)               image processing parameters;

(vi)             image display parameters;

(vii)           image archiving requirements;

(viii)         accept-reject criteria (Code reference); 

(ix)             performance evaluation;

(x)               Operator identification.

 

(b)   The system shall be aided with an image processor to enhance the quality of the radioscopic images and system performance quality shall exhibit-

(i)                 a thin section contrast sensitivity of 3%;

(ii)               a thick section contrast sensitivity of 2%;

(iii)             a spatial resolution of 3 line pairs per mm;.

(iv)             IQI sensitivity - 2% of the joint thickness when wire IQI's are to be used, the wire diameter axis shall be oriented along the axis of the least sensitivity of the system.

(c)   Radioscopes are to be properly marked to co-relate with particular part of joint represented. 

(d)   The radioscopic examination data shall be recorded and stored on videotape, magnetic disk or optical disk at the maker's plant for a sufficient period after the date of radioscopic examination as specified by the Inspecting Authority, efficient radioscopic examination record recall shall be made available at any time over the record retention period and shall be traceable to the test objects. 

(e)   When repair has been performed as a result of radioscopic examination, the repaired areas shall be re-examined using the same radioscopic technique to evaluate the effectiveness of the repair. 

(f)     To aid in proper interpretation of the radioscopic examination data, the details of the technique used shall accompany the data.  As a minimum, the information shall include the approved procedure requirements and system performance test data.


 
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