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Reg. 561 c

Test for Class II Boilers

 

i)

From each longitudinal seam test pieces shall be selected for the following tests and stamped by the Inspector for identification.

From the test plate or plates:-
One tensile test specimen for welded seam.
One bend test specimen.
One reverse bend test specimen.
One nick-break test specimen.

The disposition of the specimen shall be in accordance with the sketches in Figure XII/65. The remainder of each test plate shall be retained for retests if required.

ii) Tensile test:

The dimensions of the test specimen shall be in accordance with the sketch in Figure XII/60. Specimen 1a, and the specimen shall be cut out transversely to the welded seam. When the capacity of the available testing machine does not allow the full specimen to be tested, two narrower tensile specimens shall be substituted. These specimens shall be the full thickness of the plate at the welded joint and their breadth shall be as great as the testing machine will reasonably allow, provided the effective cross sectional area of the test piece is not less than 1 ½ square inches (see Figure XII/60 Specimen 1b). The tensile strength of the welded joint specimen shall be not less than the lower limit specified for the plate.
iii) Cold bend tests: - Two bend tests shall be made.

One specimen shall be tested with the outer surface of the weld in tension, and the other with the inner surface in tension. The specimens shall be rectangular in section and shall be cut out transversely to the weld so as to have a width not less than one-and-a-half times the thickness of the plate. The sharp corners of the specimens shall be rounded to a radius not exceeding 10 per cent of the thickness of the specimen.

The specimen to be tested with the outer surface of the weld in tension shall be prepared by cutting to waste the metal local to the inner surface of the weld, so that the desired specimen thickness is obtained (see A. Figure XII/64). The specimen to be tested with inner surface in tension shall be prepared by cutting to waste the metal local to the outer surface of the weld so that the desired specimen thickness is obtained (see B. Figure XII/64). Where the thickness of the plate permits both specimens may be cut from the same piece of plate, the specimens being located in the plate one above the other (see C. Figure XII/64).

Each specimen shall be mounted with the weld midway between the supports set apart at a distance of not more than 5.2 times the thickness of the specimen and pushed through the supports with a former having a diameter equal to three times the thickness of the specimen.

One completion of the test no crack or defect at the outer surface of the specimen shall be greater than 1/16 inch measured across the specimen, or 1/8 inch measured along the length of the specimen. Premature failure at corners of the specimen shall not be considered cause for rejection.
iv) Nick-break specimen: This specimen shall have a width not less than one-and-a-half times its thickness and the slot shall be cut in each side of the specimen through the centre of the weld and perpendicular to the outer face of the boiler.

The specimen shall then be broken in the weld and the fracture shall reveal a sound homogeneous weld substantially free from slag inclusions, porosity and coarse crystallinity.
v) Additional tests before rejection- If any of the test specimens should fail, two retests shall be made both shall meet the specified requirements.
vi) Specimen after tests: If required specimens after tests shall be at the disposal of the Inspecting Authority for examination.
vii) Radiographic or ultrasonic examination: Each lengitudinal and circumferential seams in class II boiler (including shell to end plate) shall be subjected to spot radiographic or ultrasonic examination.
 
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