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  Reg. 379

Procedure of hydraulic tests



Subject to the provisions of sub-regulation (e) of regulation 381, every boiler shall be hydraulically tested after erection at site in presence of the Inspector to 1¼ times the maximum working pressure as certified by the Inspecting Authority in Form II, to be stamped on the boiler, as free from any indication of weakness or defects.
(ii) If all components of the boiler in the manufacturer’s premises have not been tested hydraulically as per regulation 268, the test, on completion, shall be taken to 1½ times the maximum working pressure.
(iii) The temperature of the water used as medium of pressure testing shall not be less than 20°C and greater than 50°C.
(iv) The test pressure shall be raised gradually under proper control at all times so that it never exceeds by more than 6% of the required pressure and maintained for 30 minutes whereupon the pressure shall be reduced to maximum allowable working pressure and maintained for sufficient time to permit close visual inspection for leakage of pressure parts.
b) The boiler shall satisfactorily withstand such pressure without appreciable leakage or undue deflection or distortion of its parts for at least ten consecutive minutes. If the test is not satisfactory, the working pressure allowable by calculation shall be suitably reduced, unless the owner desires to make such alterations as will enable the boiler to withstand satisfactorily the hydraulic test, in which case the boiler shall again be examined after the alterations have been made, the pressure recalculated, if necessary, and the boiler tested to the satisfaction of the Inspector.
c) * At the first hydraulic test of a boiler prior to the issue of an original certificate deflection measurements shall be made before, during and after test of each furnace length, fire-box and flat end or other plates.
d) After the application of the hydraulic test the Inspector shall carefully examine the boiler inside and outside and satisfy himself that it has satisfactorily withstood the test.
e) In any case in which the safe working pressure to be allowed for a boiler cannot, owing to peculiar construction of any of its parts, be determined by calculation in the ordinary way, the Inspector shall, under the direction of the Chief Inspector, subject the boiler to hydraulic test for the purpose of determining the fitness of such parts. The amount of the test pressure to be applied in such a case shall not exceed the test pressure prescribed for the least working pressure found by calculation for other parts of the boiler or the intended working pressure whichever is less.
f) Should any part of the boiler show undue deflection or indication of permanent set during the progress of the test, the pressure shall be released immediately such indications are observed. The working pressure for the part shall be 40 per cent of the test pressure applied when the point of permanent set was reached. This procedure shall apply to any boiler at any test.
g) Hydraulic tests of boilers at subsequent examination shall, except when the Inspector expressly requires otherwise, be made after the inspection. The test pressure to be applied to boilers at such subsequent examinations shall be from one and a quarter to one and a half times the working pressure of the boiler.
h) When the internal construction of size of a boiler does not permit of the Inspector getting inside it or of examining closely all its parts, he shall see it tested by hydraulic pressure to one and a half times the working pressure at each inspection or the grant or renewal of a certificate.
i) Water tube locomotive type and all tubular boilers shall be hydraulically tested at each inspection for the grant or renewal of a certificate, unless such test is waived under the order of the Chief Inspector.
j) The Inspector may if the considers it necessary, apply a hydraulic test to any boiler at any inspection.
k) Except in the case of vertical boilers, heating surface of which is less than 18.58 sq.m. (200 sq. ft.), portable and vehicular boilers, which do not require re-erection or building in brickwork, the hydraulic test of all boiler shall be conducted only after the erection of the boiler in situ and all boilers shall after re-erection in a position different from that in which they were last examined be hydraulically tested.
* NOTE:-These deflection measurements should be entered in the Memorandum of Inspection Book before its submission to the Chief Inspector.
l) A hydraulic test shall also be taken before granting an increased pressure certificate and after repairing a boiler. However, in the case of minor repairs to the Water Tube boilers where NDT has been carried out, hydraulic testing may be dispensed with provided NDT is carried out by an approved method.
m) When carrying out hydraulic test, Inspectors shall use pressure gauges supplied by the Chief Inspector.

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