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Reg. 598, Reg. 599, Reg. 600, Reg. 601

Uptakes of Vertical Boilers

 
The working pressure for uptake tubes of vertical boilers shall be determined by the following formula:-

(i) When an internal liner is not fitted:-

W.P. = 100 (t-2) Equation XII/33.
D
(ii) When an internal liner is fitted extending below the low water level:-

W.P. = 725 x (t-1)² Equation XII/34.
D (L+24)

Where,

W.P. is working pressure in pounds per square inch.
t is thickness of the uptake in thirty seconds of an inch.
D is external diameter in inches.
L is length of the uptake in inches, measured between the circumferential seams.

In no case shall the thickness of an uptake tube be less than 3/8 inch.




Reg. 599

Cross Tubes

Internal diameter of cross tubes shall not exceed 12 inches. The working pressure of the tubes shall be determined by the following formula:-

W.P. = 200(t-7) Equation XII/35.
D

t is thickness in thirty seconds of an inch of the cross tube.
D is internal diameter in inches of the cross tube.

In no case shall be thickness of a cross tube be less than 5/16 inch


Reg. 600

Pads Welded to shell or the attachment of Flanged Mountings

(see Fig XII/90) -The size of outer peripheral fillet welds by which circular pads are attached to shell plates shall be determined by the following formula XII/36, but shall in no case be less than the inner welds or nor less than the minimum specified for plate thickness in Table XII/3:-

Lo = 2A-D1 L1 Equation XII/36
Do

Where,

Lo is size of fillet weld around outer periphery of pad, in inches.
L1 is size of fillet weld around inner periphery of pad, in inches.
A is cross sectional area of opening in shell (based on minimum thickness In square inches see Regulation 571.
Do is outer diameter of pad, in inches
D1 is inner diameter of pad, in inches.


Reg. 601

Hydraulic and Hammer Tests:-

a)
(i) Class I Boilers – Each Class I Boiler shall, on completion of all welding and/or repairs and after heat-treatment, be subjected to a hydraulic test of 1.5 times the design pressure without any indication of weakness or defect.
(ii) Class II and Class III Boilers – Each Class II and Class III boilers shall be tested to a pressure twice the design pressure.

b)
(i) The test shall be witnessed by the Inspecting Authority or Inspecting Officer.
(ii) The test pressure shall be maintained for a period not less than 30 minutes.

It is important in the interest of safety that the boiler be properly vented, so as to prevent the formation of air pockets, before the test pressure as applied.

NOTE:-

1. It is recommended that the temperature of the water should not be less than 7°C during the hydraulic test.

2. It is further recommended that before the boiler is approached for close examination, the pressure shall be reduced to not less than 1.1 times the design pressure and not more than 0.9 times the hydraulic test pressure.

3. On completion of hydraulic test, release of pressure shall be gradual.

4. Deflection of different pressure parts shall be examined carefully and there shall not be any permanent set after release of pressure
c) If any repairs are found to be necessary during or subsequent to the hydraulic pressure test, the boiler shall again be subjected to the pressure test specified above after completion of the repairs and after any heat treatment.

NOTE:-
Observations and remarks of Inspecting Officer/Inspecting Authority should be recorded for filming with makers’ papers.
 
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