 |
| |
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. |
|
|
