1-According to which law or
regulation Boiler hydraulic tests are conducted?
Boilers
hydraulic tests are conducted as per IBR 1950 Regulation 379
2-Why do Boilers Hydraulic tests are
conducted?
- To ensure
there is no leakages in joints after erection & welding works
- To ensure the
healthiness of pressure parts & correctness of workmanship
- To identify
the weakness & defect of pressure parts
- To complete
the compliance of Boiler inspector authority
- To avoid any
incidents during boiler start up or operation
3-When shall you conduct Boiler
Hydraulic tests?
Boiler
Hydraulic tests are carried out;
- After
erection of new Boiler
- After
replacement of drum gaskets
- After any
repair works in pressure parts
- After repair
of replacement of critical (root valve, MSSV, MSNRV) valves
- Yearly as per
Boiler inspector compliance
- After any
alteration or modification in pressure parts
4-At what pressure do you take the
Boiler Hydraulic test?
Boiler
Hydraulic tests should be taken at pressure 1.25 times the maximum operating
pressure or Design pressure of the Boiler
5-When shall you carryout Boiler
hydraulic test at 1.5 times the maximum operating pressure or Design pressure
of the Boiler?
If all the Boiler components are not tested in
manufacturer premises as per Regulation 268, then Boiler hydraulic test should
be conducted at pressure 1.5 times the maximum operating pressure or Design
pressure of the Boiler.
6-What is
the recommended temperature of Water for Boiler Hydraulic test?
The temperature of the water used as medium of pressure
testing shall not be less than 20°C and greater than 50°C.
7-What
are the desired parameters of water used for Boiler Hydraulic test?
Boiler water parameters
- PH-8.5-9.2
- Conductivity-5-10
mic S/cm
- Silica-0.02
ppm
- Hardness-Nil
8-Up to what time you are going to
hold the Boiler at Hydraulic test pressure?
Boiler can be
held up to 30 minutes at rated Hydraulic test pressure
9-When shall you conclude the
completion of Boiler Hydraulic test?
The boiler
shall satisfactorily withstand maximum allowable operating pressure without
appreciable leakage or undue deflection or distortion of its parts for at least
10 consecutive minutes.
10-Is test pressure affects the
Boiler ageing?
Yes, Boiler
hydraulic test pressure should be reduced based on their ageing
11-What you will do if you observed
any defects or deflection in Boiler parts during hydraulic test?
In such
cases, Boiler hydraulic test should be stopped immediately & pressure shall
be released
12-Is Pneumatic testing of Boilers
is recommended before hydraulic test?
Yes pneumatic
test of Boiler is done at pressure around 2-3 kg/cm2 to ensure
leakages to avoid loss of DM water.
13-What is the rate of pressure
rising during Boiler Hydraulic test?
It is around
3 to 3.5 kg/cm2/minute
14-Explain the Boiler Hydraulic test
procedure
Preliminary checks
- Ensure Boiler
erection & maintenance related works are completed
- Ensure Boiler
feed pumps are healthy & ready to use (Ensure 1W+1S)
- Ensure
Initial water fill up line & pumps are ready to use
- Ensure required
quantity of DM water is available
- Ensure DM
water parameters are normal
- Ensure DM
temperature is 20 deg C to 50 deg C
- Ensure
Pressure gauges are mounted at steam drum, super heater & any other
required location
- Ensure the
transmitters/pressure parts whose operating /hydraulic pressure is not
recommended for hydraulic test are isolate
- Ensure
sufficient number of competitive team is available for conducting test
- Ensure safety
valves gags are available & kept near safety valves
- Ensure,
hydraulic test planning is done properly
Procedure:
- Keep open
Boiler’s all drum, super heater & economiser header air vent valves.
- Ensure all
drain valves of drum & headers are closed
- Fill the
Boiler, by initial fill up line by starting Deaerator or feed water tank make
up pump.
- If Boiler is completely
empty, it will take 2 to 3 hours’ time to fill the Boiler (It depends on size
of initial fill up line)
- After filling
the Boiler water will come out from vents of economiser, drum & super
heater header.
- Initial close
the economiser header vents
- Then close
the Super heater & drum vents at pressure > 2 kg/cm2 to ensure air
present in water is vented out completely (Sequence of vent closing should be
from bottom elevation to top)
- After closing the vents slowly raise the Boiler pressure
by starting Boiler feed water pump or reciprocating pump (For newly erected
Boilers, feed pumps may not available, so in such cases separate positive
displacement pumps of required head are made available)
- Ensure, initially the pressure rising rate is 3-3.5 kg/cm2/minute
up to 25% of Hyd.test pressure, after that raise the pressure at rate 1 to 2
kg/cm2 / minute.
- AT pressure 4 to 5 kg/cm2, flush the pressure gauge impulse
lines & mount pressure gauges
- After reaching Boiler pressure 90-95% of the operating pressure,
mount the gags & apply force to ensure gags are fitted properly
- Then continue pressurizing until Boiler pressure reaches
the hydraulic test pressure. Ensure hydraulic test pressure not crossed the 6%
of maximum allowable pressure
- Hold this pressure for 30 minutes & then release the
pressure to normal operating pressure
- Then inspect all the joints, valves glands, other pressure
parts for leakages & deflection.
- Once found normal, release the Boiler pressure through
blow down valves
- AT pressure 10-15 kg/cm2 flush Boiler bottom headers
- Remove the gags
- Open the vent valves
Read Boiler refractory dry out procedure
Questions & Answers on steam blowing