FIELD OF INVENTION
The present invention relates to a fixture made for carrying out local hydraulic and
pneumatic testing of weld seams of additional flanges added on an already hydraulically
and pneumatically tested stator frame and a method for the same. More particularly, the
invention relates to the design of a fixture so that the hydraulic and pneumatic testing of a
complete stator can be avoided during the repair of a stator.
BACKGROUND OF THE INVENTION
BHEL haridwar is receiving 2-3 stators every year for rewinding / core repair. Customer is
demanding duplex RTDs in core as well as windings. For this purpose additional flanges in
stator frame are required for taking out leads of these additional cables of RTD. This
involves drilling holes in stator frame and welding flanges.
The stator is already hydraulically and pneumatically tested during first time
manufacturing. But as new weld seams are being added due to addition of new flanges,
stator needs to be tested hydraulically and pneumatically again to check the soundness of
the new weld seams. It is not possible to perform complete hydraulic and pneumatic
testing of the stator again because stator core is already present in the stator.
Hence, there was a need to design a fixture so that new weld seams can locally tested
rather than hydraulic and pneumatic testing of the complete stator again.
OBJECT OF THE INVENTION
Therefore, it is an object of the invention to design and manufacture a fixture for local
hydraulic and pneumatic testing of weld seams of flanges added to a stator frame.
Another object of the invention is to design and manufacture a fixture for hydraulic and
pneumatic testing of weld seems in order to avoid hydraulic and pneumatic testing of
complete stator.

A further object of the invention is to design and manufacture a fixture for hydraulic and
pneumatic testing of weld seams for stator frame as well as for testing additional weld
seams of any other pressure vessel which has already been hydraulically and pneumatically
tested.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The invention will now be described with the help of the accompanying drawing where:
Fig. 1 shows a fixture with additional flange having provision for inlet / outlet of water /
air.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT
OF THE INVENTION
The fixture (F) to be used for local hydraulic and pneumatic testing of weld seams consists
of the following items.
(i) Ring (1) (ii) flange (2) with provisions for inlet (9) / outlet (10) of water / air (iii) plug
(3) (iv) nipple (4) (v) blank flange (5).
During repair of a stator a hole is drilled in the stator frame in the location where additional
flange (6) is to be added. Flange (6) is welded to the stator (7). For the purpose of
testing this new weld seam (8) a 'RING' (1) is temporarily welded to the stator frame (7)
around the additional flange (6). The additional flange (6) is then closed with a blanking
flange (5) with the help of gaskets. The ring (1) is closed with a flange (2) having the
provision of water / air inlet (9) and outlet (10). The water outlet is then closed using a
plug (3) and water is filled in the chamber (12) through inlet (9) through a nipple (4) till
pressure in the pressure gauge (11) reaches (10) bars. This pressure is kept for 30
minutes. If there is no drop of pressure this means the weld seam is leak proof other wise
it indicates that there is leakage in the weld seam. After successful hydraulic testing the
weld seam is once again tested with air at 6 bar pressure for 30 minutes. A successful
hydraulic and pneumatic testing indicates a leak proof weld seam of additional flange.
After the test the fixture (F) is removed from the stator (7).
WE CLAIM
1. A fixture (F) for carrying out local hydraulic and pneumatic testing of weld seams of
additional flanges added on an already hydraulically and pneumatically tested stator
frame comprising:
- a ring (1) temporarily welded to the stator frame (7) around the additional flange
(6);
- a flange (2) closing the ring (1) with provision for inlet (9) and outlet (10) of water
or air;
- a blanking flange (5) closing the additional flange (6) with the help of gaskets;
a pressure gauge (11);
characterized in that,
- the flange (2) is provided with inlet (9) and outlet (10) for water or air wherein the
outlet is closed with a plug (3) and the inlet is equipped with a nipple (4) for filling
the chamber with water and air.
2. A method for carrying out the local hydraulic and pneumatic testing of weld seams
of additional flanges added on already hydraulically and pneumatically tested stator
frame comprising:
- closing the water outlet (10) of the flange (2) with a plug (3);
characterized in that,
- the chamber (12) is filled with water through inlet (9) provided with a nipple (4) till
pressure in the pressure gauge (11) reaches 10 bars which is maintained for 30
minutes for checking the drop of pressure wherein the weld seams is then
subjected to testing with air at 6 bar pressure for 30 minutes for checking again the
drop of pressure.

A fixture (F) for carrying out local hydraulic and pneumatic testing of weld seams of
additional flanges added on an already hydraulically and pneumatically tested stator frame
consisting of a ring (1) temporarily welded to the stator frame (7) around additional flange
(6). A flange (2) closing the ring has provision for inlet (9) and outlet (10) of water or air.
A blanking flange (5) closes the additional flange (6) with the help of gaskets. A pressure
gauge (11) is disposed in the fixture to check the pressure when the flange (2) is provided
with inlet (9) and outlet (10) for water or air wherein the outlet is closed with a plug (3)
and the inlet is equipped with a nipple (4) for filling the chamber with water and air for
checking the drop of pressure hydraulically or pneumatically.