60
103536-13 - 2/24
MegaSteam
Installation & Service Manual
Appendix A
Steam Boiler Skimming
Steam Boiler Skimming
ALL STEAM BOILERS REQUIRE PROPER SKIMMING. THIS NOTICE WILL HELP CONTRACTORS COMPLETE
STEAM BOILER INSTALLATIONS AND AVOID CUSTOMER CALL-BACKS
Background
Skimming removes oil from the boiler water volume. If not removed properly oil can reduce steam generation and
make the boiler surge. A boiler is surging when the water level in the gauge glass is bouncing or not visible while
boiler is producing steam. Oil can originate from the inside of black pipe, or from petroleum based thread sealant or
from the lubricant used in the cast iron hole threading process. Less than perfect near boiler piping may also make
skimming more important.
This process combines best practices learned from a number of skilled, experienced technicians, and it can be
completed in about an hour. No chemical additives should be needed.
Recommended Skimming procedure:
1.
Prepare at least two empty buckets. Find a close place to dump water.
2.
Turn on the boiler. Run it until it is hot and starts to make steam.
3.
Turn off the boiler.
IMPORTANT - DO NOT TURN BOILER ON DURING SKIMMING PROCESS
.
4.
With Caution, lift valve and verify that there is no steam pressure in the boiler.
5.
Find the skim tapping or a plug you can safely remove above the water level. This tapping must be at least
3/4 in. A relief valve tapping may be used.
6.
Install a nipple with a full-port ball valve into the boiler tapping. This valve is a "just-in-case" valve. You will
not close this after the skimming process starts. This pipe nipple must be horizontal, and must come straight
out. It can not elbow up. We are trying to skim the water surface, therefore the water must come off a
horizontal pipe. There should not be water at this level yet.
7.
Open the valve you installed. Hang a bucket on the pipe.
8
.
Find the manual fill valve.
If there is no manual valve, add the water to the boiler through the bottom
drain valve on the boiler.
9.
Open the manual fill valve until the water starts to flow slowly out of the pipe nipple and valve installed
earlier. When water flows out the pipe nipple, close the fill valve and wait until the flow stops.
10.
Reopen the manual fill valve slightly so the steam of water coming from the pipe nipple is no larger than a
wooden pencil. Slower flow is best.
11.
Continue to skim until the bucket is almost full. Remove the full bucket and use the second bucket while you
dump the first. Do not shut off the valve while doing this. You can not stop the water once you have started
the flow.
Remember - Do not re-fire the boiler
.
12.
Keep skimming until the water temperature is comfortable to the human hand.
13.
When done skimming stop adding water. Drain the water to the proper fill level.
14.
Remove the pipe nipple and valve. Re-install the plug or relief valve.
15.
Turn the boiler back on and let it create steam. Decide if the surging stopped or improved. You may redo this
process, but this should not be required.
16.
If there is no improvement after two tries then the problem is not oil-related. Consider checking near boiler
piping, flame impingement, or water pH. Low water pH or water treatment chemicals can also cause
foaming and/or surging.
