1-According to which law or regulation Boiler hydraulic tests are conducted?
hydraulic tests are conducted as per IBR 1950 Regulation 379
2-Why do Boilers Hydraulic tests are
- 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 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?
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.
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.
are the desired parameters of water used for Boiler Hydraulic test?
Boiler water parameters
- Conductivity-5-10 mic S/cm
- Silica-0.02 ppm
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?
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
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?
cases, Boiler hydraulic test should be stopped immediately & pressure shall
12-Is Pneumatic testing of Boilers
is recommended before hydraulic test?
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
- 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
- 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