Leak Test Procedure Of Boiler

Procedure for Leak test of Boiler Air and Flue Gas Path For Leak test of Parts, following methods can be used. 1. Leak Test with Smoke 2. Kerosene Test

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WHEN TO CARRY OUT LEAK TEST:

Leak test essentially need to be conducted just after erection completion of Parts of Air & flue gas path and before Insulation. This can be done as a complete system or in parts. Generally following areas of Boiler need to undergo Leak Test. •

Furnace/combustor

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Second Pass Flue gas

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Third Pass Flue gas

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Hoppers

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ESP

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APH

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FD Duct

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PA Duct

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SA Duct.

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Pollution control equipment to ID Fan

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Stripper cooler

1. Smoke Test: This test is similar to air and gas leak test with an addition of smoke generation in the boiler before pressurizing. For pressurizing smoke, a suitable blower (suggested minimum 3 HP) to be used. In case FD fan is available at time of leak testing, the same may be used instead of temporary blower. Similarly, for ESP testing purge air fan may be used where available. Any leakages shall be identified visually by smoke coming out from leaking areas. Smoke can be generated by smoke bombs, smoke generating machines or by firing wood/ jute/ cotton waste etc.

2. Kerosene Test: This test is conducted for detecting the leakages thru the weld joints normally in ducts. A paste of lime/ chalk is applied on one side of the joint and after drying, Kerosene is sprayed on the other side of the joints.

The leakage areas shall be seen as wet areas on the side where lime/ chalk is applied. This test to be used for components on ground before erection (Ducting, hoppers, Casings etc).

WARNING : Smoke generating machines using petroleum fuels must not be used as there is a fire/ explosion hazard. Machines using organic chemicals like Glycerine & Rose water can be safely used. Care must be taken while handling Kerosene for the fire hazards

Smoke test procedure: •

Isolate the portion of the items to be tested like furnace, APH, FGD, SA and wind box to be tested by providing adequate blanks such as insulating mattress/cladding sheet/gasket sheet etc. depending on the size of opening.

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Place the smoke generating machine/machines on the bottom most portion of the volume to be tested. The quantity and size of machine shall be according to the volume to be tested.

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Roughly one machine for every 250 M3 shall be used. There shall be a vent with size not more than 75 mm OD on top most portion of the volume to be tested. It can be hole for sky climber, peep hole Etc.

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The smoke generation shall proceed till smoke is visible from the vent hole.

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Record and mark the location of leakages where the smoke is emitting.

WARNING : Please do not make deliberate hole on the equipment. Vent Hole can be made on the blanks being used

Smoke Generator Machine operating procedure: Smoke generator machine is used for leak test of furnace/combustor, Air and flue gas ducts and hoppers. Following steps are to be followed for operation of this machine:-

Fill a mixture of 40% rose water and 60% glycerin in the smoke generator machine cylinder (i.e. 2 litre Rose water and 3 litre Glycerin for a 5 ltrs capacity machine) In smoke generation machine two red lights (upper / lower) are given. - Electrical supply indication (Upper) - Temperature indication (Lower) Whenever machine is plugged in with electric supply, both red lights will glow. After starting the machine, set the temperature in between 250 to 270 deg C. After attaining the temperature, lower light will be Off in auto mode. Now start the pumping in the cylinder. After completing the pumping in the cylinder, crack open the discharge valve and observe the smoke. When the smoke intensity reduces and liquid starts coming out of the discharge pipe, close the discharge valve and again start the pumping for the next cycle. After mixture of rose water and glycerin is exhausted, start again from Step -1 and repeat the same.