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Reg. 561 a, Reg. 561 b

Tests on welded seams

(a) Test Plates

 

Test plates to represent all welded seams shall be attached at each end of each longitudinal seam in tension. These shall be of a size sufficient for the preparation of the test pieces specified. In the case of shell plates up to an including 16 feet in length the test plate may be located at one end only (see Figure XII/58). Where the shell is formed in two or more rings, the staggered longitudinal seam shall be regarded as a continuous longitudinal seam provided the welding be effected in one reasonably continuous operation and by the same operator or operators. The material for the test plates shall be cut from the respective plate or plates forming the appropriate seam.

In the case of insufficient material being available on the shell plate to permit the cutting of test pieces, these shall be acceptable if they are made from another plate provided it is made from the same cast. The test plates shall be stamped by the Inspecting Authority before being cut.

The weld groove in the test plates shall be similar to that adopted for the corresponding edges of the longitudinal seam, and the respective fusion faces shall be in continuous alignment. The test plates may be reinforced or supported during welding so that any relative displacement due to warping during welding does not exceed 5 degrees. The weld metal in the test plates and the seam shall be deposited continuously at the same operation.

The weld in any test plate shall not be repaired. If any defects are revealed in the weld metal of a test plate the position of this shall be clearly marked on the plate and the test pieces shall be selected from such parts of the test plates as may be decided by the Inspecting Authority.

Test plates warped during welding by not more than 5 degrees may be straightened before heat-treatment. For the heat-treatment of the test plates see Regulation 562.

Where there are circumferential seams only or where the method of welding the circumferential seams differ from that employed for the longitudinal seams, the method of providing the test plates shall be decided by the Inspecting Authority.




Reg. 561 


(b) Test for Class I boilers

i)

Specimens for the following tests shall be selected from the test plate or plates and stamped by the Inspecting Officer for identification (see Figures XII/58 and XII/59):
One tensile test specimen for the welded seam.
One all weld metal tensile test specimen.
Two bend test specimens.
Two impact test specimens.
One specimen from each test plate for macro and micro examinations.

The dimensions of the specimens shall be in accordance with the sketches in Figures XII/60, XII/62, XII/63 and XII/64. The remainder of the test plates shall be retained for re-tests if required. Any specimen for re-test shall be cut from the same test plate as the original specimen. Specimens representing welded seams shall, if necessary, be straightened cold before the commencement of machining. Tensile and bend specimens shall, if practicable, be of the full plate thickness. Surfaces of tensile, bend and Izod specimens corresponding with the outside or inside of the boiler shall be lightly dressed only so that the rolled surface of the parent metal is not wholly removed. Where the rolled surfaces of the abutting plates are not level with one another one plate may be machined at each face of the weld so long as the depth of the metal removed does not exceed 1/32 inch.
ii) Tensile tests:-

(a) (i) Welded joint: –

The dimensions of the reduced tensile section shall be as shown in the Fig 60-1(a).The width of the reduced section shall be at least 25 millimetres.

(ii) If the thickness of the plate does not exceed 30 millimetres, the thickness of the specimen shall be equal to the plate thickness and the plate surface of the specimen shall be machined to take away the surface irregularities of the plate and the weld.

(iii) If the plate thickness exceeds 30 millimetres, the tensile test shall be carried out on several reduced section specimens, each having a thickness of at least 30 millimetres and width at the effective cross-section of at least 25 millimetres. These specimens shall be taken out of the test piece in such a way that the tensile test covers the whole thickness of the weld joints as shown in Fig 60-1(b) . The tensile strength shall not be less than the lower limit specified for the plate.

(b) All weld metal:–

The dimensions of the weld metal tensile test specimen shall be these given in figure 63. The diameter shall be the maximum possible consistent with the cross section of the weld but in no case more than 20 millimetres, the gauge length shall be equal to five times the diameter. The tensile strength shall not be less than the lower limit specified for the plate. The elongation shall not be less than 20 per cent on a gauge length of five times the diameter of the specimen or 5.65 times the square root of the cross-sectional area of the specimen, and the reduction in area not less than 35 per cent.
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 plates. The sharp corners of the specimens shall be rounded to a radius not exceeding 10% of the thickness of the specimen.

Where the plate thickness does not exceed 1 ¼ inches, the thickness of the specimen shall be equal to the full thickness of the test plate. Where the plate thickness exceeds 1 ¼ inches, the specimen shall in all cases have a thickness of at least 1 ¼ inches. 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 the 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.

On completion of the test no crack or defect at the outer surface of the specimen shall be greater than 1/16 inch measured cross 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.

On completion of the test no crack or defect at the outer surface of the specimen shall be greater than 1/16 inch measured cross 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.
 
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