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Reg. 561 a, Reg.
561 b
Tests on welded seams
(a) Test Plates
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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.
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Reg. 561
(b)
Test for Class I boilers
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i)
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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:
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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.
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| (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.
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| 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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