Boiler Maintenance Hints

Boiler Gauge Glass

How to Clean

Follow these simple steps to clean gauge glass while steam pressure in on boiler and without disassembly.

1. Fill a cup with ordinary household ammonia.
2. Close top and bottom gauge valves. Open drain valve beneath column.
3. Barely open the top gauge valve so steam pressure blows all the water out the drain line and glass contains only steam.
4. With a very gentle flow of steam out of the drain line, hold cup of ammonia to the end of the drain line so steam bubbles up through ammonia.
5. Close top gauge valve. Steam will quickly condense in the gauge causing a vacuum. The resulting contraction will suck ammonia into the gauge glass.

Repeat until the gauge glass is sparkling clean.

Full or Empty?

When no water level shows on a sight glass, you can quickly tell whether it is completely full or completely empty.

Hold a pencil against the far side of the sight glass tube at an angle of approximately 45 degrees. If the image of the pencil viewed through the glass appears to run across the glass and changes little no matter what the angle of the pencil, the glass is full.

However, if the image viewed through the glass runs up and down the glass at a sharper angle than the actual angle of the pencil, the tube is empty.

Check this difference with normal water level before an emergency by viewing through the sight glass above and below the water line. Thick wall tubing gives a less pronounced difference, but a real difference, nevertheless. A little practice will take away any uncertainty.

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Boiler Care Facts and Care Tips

1. A Coating of scale is a coating of insulation. It will:
   • Lower the efficiency of a boiler causing it to use more fuel.
   • Cause fire surface temperatures to rise beyond their designed temperatures.
   • Insulate fusible plugs, greatly changing their melting temperatures.

   

2. If the cover plate is too small for the opening in the boiler it is easy to place the cover plate off center. An off-center inspection plate can concentrate forces on the gasket and cut it in two. The plate may also drag on the shell and fail to seal as the pressure rises, such as:
3. After start-up, crabs should be re-tightened as pressure comes up and the gasket seats in. A loose crab on bottom or below water line can cause a boiler to drain on shutdown as steam pressure lowers to zero.
4. Regular blow down of a boiler removes sludge collected in the bottom of a boiler, but is no substitute for proper water treatment which stops the formation of both sludge and scale. Boiler repair and water treatment agencies in your area know best what your water may require.
5. A fusible plug changes its melting point with time and temperature and should be replaced yearly for that reason.
6. Low water level being one of the most dangerous of boiler conditions, gauge glasses should be kept clear and operating at all times. Try cocks should be kept only as a means of checking gauge glass readings and as a back-up system while repairing gauge glasses.
7. Fuel efficiency changes gradually. A regularly scheduled maintenance program makes better sense as fuel prices rise.
8. A "slow" pressure gauge indicates that its anti-syphon nipple is filled with scale and rust and its readings are inaccurate. Brass pigtail nipples are generally more trouble-free.
9. Grease or oil in a boiler is not good. It usually causes "priming" or "foaming," and is usually visible on top of the water in the gauge glass. Remedy: Skim the water in the boiler before draining - refill and add soda ash to cut grease.
10. A gasket that leaks is eroding the boiler it is supposed to help

Properly installed Topog-E gaskets do not leak!

Caring for an Out-Of Service Boiler

There are two primary ways to care for an out-of-service boiler. These are usually chosen on the basis of whether freezing temperatures will exist while the boiler is stored and whether the boiler may be needed for service on short notice. The boiler can be stored dry or wet. In either case, it should be thoroughly cleaned before storage.

Dry Storage

The cleaned boiler should be thoroughly dried. Any moisture will cause corrosion on long standing. All lines to the boiler that could carry moisture back to the boiler must be blocked off. Remember, even air can carry moisture.

Moisture absorbing material may be placed on trays inside the shell at the rate of 2 lbs. of quick lime or 10 lbs. Of silica gel for each 1,000 gal. of capacity. Periodic inspections of the effectiveness of these materials are recommended during extended storage.

Wet Storage

The cleaned boiler should be closed and filled to overflowing using chemically conditioned water (condensate is purer than feedwater for this purpose). Caustic soda is often used for this treatment at a concentration of 450 ppm with an oxygen scavenger such as sodium sulfite at 200 PPM Water pressure greater than atmospheric should be maintained during storage.

Boilers safety valves are little understood, often incorrectly installed, and usually neglected. That is a general statement, and as with most general statements, must not be taken as universally true. However, there is enough truth there to warrant some discussion of the valves.

The term "pop valve," often applied to safety valves, is not a bad term in that it accurately describes the action of the valve. As the pressure of the steam within a boiler approaches the set pressure of the valve, the steam pressure on one side of the actuating disc approaches the pressure of a spring applied to the outer side of the disc. When equilibrium is passed, the disc starts to lift off its seat. The moment this happens, steam is suddenly released all around the disc. This escaping steam strikes an additional shoulder around the circumference of the disc thus increasing the area of the disc that sees steam pressure. This sudden increase in area under pressure makes the pressure much more unbalanced in the direction of opening, which pops the valve to the wide open position. This pop action prevents wiredraw of the seat due to slow action.

Closure of the valve occurs only after the boiler pressure has dropped several pounds below the set point. This is due to the increased area of the disc that sees steam pressure after the valve unseats. To ensure tight closure after a valve has popped under pressure, the boiler maximum operating pressure should be set several pounds below the set pressure of the safety valve. Some manufacturers recommend setting ten percent or more below.

Proper installation of a safety valve is a result only of careful adherence to the manufacturer's instructions. In general these will concern themselves with two areas: distortion of the valve itself and proper piping.

There is some discussion in the field about whether or not is wise to periodically pop a steam safety valve. Since there is the possibility of a valve becoming incapable of proper operation due to scale coating inactive parts. The Hydronics Institute in their Operation and Maintenance Manual for Steel Boilers recommends an operations check on safety valves at the beginning of the heating season and every six months. Their recommended method is to raise the pressure until the valve pops. Whether by this, or if the hand lever is used, the pressure should be as high as practical to blow the seat and other parts clean of foreign matter.

A safety valve body is part of the precision of the whole device. Distort the body, and the accuracy of the valve's calibration is destroyed. Care must be taken to apply wrenches in only the place required for installation.

Similarly, on the discharge side, the valve body must not be made to bear the weight of the discharge piping. Distortion could occur. A short nipple from the valve body should enter the mouth of an independently supported large bell reducer or a drip pan elbow leading through large piping to a safe discharge area or preferably, the outdoors. All piping to or from a safety valve must be at least as large as the safety valve's connection and the restrictive effect of elbows and the friction losses in pipe must be taken into account. For this reason, runs should be as short as possible and pipe sizes should be generous.

For a safety valve to do its job, it must be sized so that when open it will adequately relieve all the steam the boiler is capable of producing while operating at its maximum.

The purpose of the valves is safety, therefore, they are worth a little attention to give them their best chance to work.