LOW WATER IN YOUR BOILER
Posted in low water cut-off by Boiler Guy on April 8th, 2008 BOILER - LOW WATER
The effect of low water in a boiler could result in, at the least, a leakage and, at the worst, a catastrophic explosion, depending on the severity of water loss and the boiler design. Without the water to surround the crown sheet over the firebox the exposed metal reaches such an extreme temperature that the tensile strength decreases to dangerously low point and fails.
In a fire-tube boiler, a low water condition will expose the tubes to high temperature gases, expanding the tubes to such a great extent that they will break the rolled in seat with the tube sheet. Leaks can be detected as a result of this expansion and may even result in the tubes collapsing.
Regardless of the boiler design, it is obvious that low water is a situation that must be avoided at all costs. Anthony L Kohan, author of “The Boiler Operator’s Guide”, recommends the following procedure “if water is not visible in the gauge glass because of failure of the feedwater supply…”
1. Shut off fuel to the burners.
2. Check the water level by trying the try cocks and water-column drain. If definite low water is indicated below the gauge-glass level, close the main steam valve and feedwater valve.
3. If the boiler is equipped with one, open the superheater drain.
4. Continue operating forced-draft and induced-draft fans until boiler cools gradually.
5. Let the pressure reduce gradually and when the furnace area is sufficiently cooled, check for leaking tubes and other signs of over-heating damage. On firetube boilers, look for cracked or wrapped tube sheets, broken and leaking stay bolts in the water legs. On scotch marine boilers, check for cracked or leaking furnace-to-tube sheet welds. On cast-iron boilers, look for cracked sections. On steel boilers, check for leaking joints on longitudinal or circumferential welds or riveted joints.
6. If no leakage is evident, give the boiler a hydrostatic test of 1-1/2 times the allowable working pressure. Then again check for leak-age at all critical parts of the boiler. If leakage is observed during the initial check or during the hydrostatic test, notify the authorized boiler inspector immediately so that she or he can inspect the boiler and advise on permissible repairs.
Debasis said,
April 18, 2008 @ 7:34 am
What is the need of ph maintenance in boiler water?
What are the qualities of boiler drum water 7 make up dm water?
José Rosado said,
April 18, 2008 @ 7:17 pm
I am operating a Sioux Boiler for disinfecting soils, sometimes we suffer blacks out in our main power lines. So our boiler shutdowns and when the electric energy returns again it tries to ignite but fails. I checks the electrodes, clean it and assembly back the all set (nozzles and electrodes). There comes the main problem, the burner begins to back firing in a noisy and dangerous way. Think it might be for the fuel oil that remains in the firing tube.
Jay said,
April 22, 2008 @ 3:45 pm
Hi Debasis,
Not all boiler water chemistry treatment programs directly monitor boiler water pH. Boiler water chemistry has a direct impact on boiler efficiency and fuel use. Improper water treatment will allow increased corrosion and scale formation. Scale insulates boiler tubes and requires increased fuel use. Corrosion will lead to tube failure resulting in loss of use of the boiler until repairs are made.
Not following proper boiler water chemistry can quickly destroy a boiler. I have seen new boilers destroyed in less than six months due to improper boiler plant chemistry controls!
Your boiler chemical supplier will set up the proper water treatment program for your boiler. Follow the boiler chemical supplier’s recommendations and your boiler will last at least for its expected lifetime.
Hope this Helps!
Jay I. Hoar
Service Manager
http://www.mckenziecorp.com
Jay said,
April 22, 2008 @ 3:54 pm
Hi Jose
You need a QUALIFIED BOILER SERVICE TECHNICIAN to take a look at your boiler immediately! As you stated the “burner begins back firing in a noisy and dangerous way”. If all of your boiler’s controls and components were working properly and set up correctly this would not happen.
Have a QUALIFIED BOILER SERVICE TECHNICIAN take a look at your boiler immediately! Not doing so may result in a furnace explosion.
Jay I. Hoar
Service Manager
http://www.mckenziecorp.com