Zwicker’s Revised Practical Instructor IN QUESTIONS AND ANSWERS for Machinists, Firemen, Electricians and Steam Engineers


This book is written for the special information of Engineers, Machinists, Firemen and Electricians who have to sooner or later procure an engineers license by going before a board of practical engineers and answering questions relating to the care of boilers, pumps, injectors, engines, indicator safety-valve and electric light dynamo before they can collect their salary as an engineer. It is hoped its practical suggestions will enable those who follow them to gain a better insight of the work they have to perform. The real object in writing this book is to help my fellow man and not keep him in the dark. All questions are answered in plain and simple language, so any man of limited education can thoroughly understand.

Q. What are the duties of an Engineer?
A. His duties are to take full charge of the boilers and engines where ever he may be employed, and see that the steam machinery under his charge are kept in No. 1 order with little expense to his employer.

Q. What is required of a man to become a first class Engineer?
A. His is obliged to obtain an Engineers license touching his qualifications as an engineer of steam engines, by which will be shown that he is a suitable and safe person to be entrusted with the powers and duties of an engineer.

Q. What experiences must a man have in order to get his application before a board of Engineers?
A. His experience must be generally two years, at mechanical or steam engineering, which must be sworn to by two citizens, one being a licensed engineer and the other a good reliable citizen, both living in the city, where applicant has worked.

Q. What is a steam boiler, how is it, and of what is it made?
A. A steam boiler is a closed vessel made of steel, iron or copper plates, the most in use is 3/8, ? and 6/16 inch thick, and ranging from 45,000 to 85,000 lbs. tensile strength; these plates are run through a rolling machine and rolled in a circle, then riveted together, generally with two rows of rivets, because the strain is greater sidewise than endwise, the seams around the boiler are single riveted because the strain is not so great; the boiler is braced by different kinds of braces, such as a crow foot, Longitudinal dome, side braces, etc. The eye is riveted to the head of the boiler, which head is generally made of 5/8 inch plate, the other eye is riveted to the side top or dome of boiler, and the brace and eye are put together by bolts with a split key to keep the bolt in its place.

Q. Which are the chief points in the construction of a successful and economical boiler?
A. Proper circulation facilities constitute one of the chief points in the construction of a successful and economical boiler. In tubular boilers, the best practice is to place the tubes in vertical rows, (plumb) leaving out what would be the center row. The circulation is up the sides of the boiler and down the center. Tubes set zigzag or to break spaces impede the circulation and will not practically give the best results.

Q. How should a brace fit?
A. It should fit tight, for if it were loose it would be of no account.

Q. If you found a brace loose, what would you do, and how would you tighten it.?
A. By taking the brace out, heat it in the center, then upset it by jumping it endwise on a block of wood until it is the proper length.

Q. Why is a boiler braced?
A. For strength.

Q. What is a stay bolt?
A. A Stay bolt is a screw bolt, put through an outside and into an inside sheet, so as to hold them that they may not spread or collapse, such as a fire box sheet and an outside shell, they are put together with stay bolts so as to allow a water space between the two sheets.

Q. How are stay bolts made and put in?
A. They are made with one continuous thread, and screwed through the outside, then through the space between, then through the fire box sheet and allowed to stick through 3/16 of an inch, so they can be riveted over each end to act as a brace, the space between the two sheets is called a water space.

Q. What is meant by corrosion?
A. It means wasting away of the iron of boilers plates by pitting, grooving, etc. There is internal and external corrosion; the acids in and minerals in the water liberated by the heat, attack the boiler internally, and the sulphur which comes out of the coal has a strong attachment for iron, and that attacks the outside.

Q. How would you find the water level when your boiler is foaming?
A. The proper way would be to shut down the engine and all valves connected with the boilers, cover fire with ashes, close the damper, then the water will quiet down, and the level of the water easily found. An engineer should know when lighting a fresh fire, never to force it, but let it heat gradually, so that all parts expand as near equal as possible; good judgment is needed. Boilers and steam gauges should be tested at least once a year.

Q. Where would you put a steam gauge?
A. Sometimes on top of the boiler, and in some cases on the steam drum. It must always be tapped into the steam part of the boiler, the shorter the pipe the better. The steam gauge and safety valve should correspond under all circumstances.

Q. Why is a pet cock put under the steam gauge?
A. To drain the pipe in cold weather.

Q. What kind of a steam gauge have you got?
A. A Spring gauge.

Q. What is a steam gauge for?
A. To indicate the pressure in pounds per square inch in the boiler.

Q. Does the steam gauge get out of order?
A. Yes, sometimes.

Q. If the steam gauge was out of order what would you be governed by?
A. By the safety valve.

Q. How would you know that it was in working order?
A. By raising the lever two or three times to see that the valve is not stuck.

Q. What is a safety valve for?
A. It is intended to release the boiler and prevent explosions from over pressure.

Q. How large should the safety valve be in proportion to the boiler, and grate surface?
A. The safety valve should be ? square inch to each square foot of grate surface, which will make it large enough to relieve the boiler of all steam generated over which the safety valve is set.

Q. Which are the better, gauge cocks or glass gauges, and which would you be governed by?
A. Gauge cocks, because glass gauges are liable to get stopped with mud, and not give a true level of the water, but they are a very handy thing; they should be blown out four or five times a day, so as to keep them from clogging up.

Q. What would you do in case a glass should happen to break?
A. First close the water valve to prevent the escape of water, close the steam valve, insert a new glass, then turn on the steam valve first, the water valve next, then close the pet cock at the bottom and everything will be all right.

Q. What is the best way to clean a glass gauge inside?
A. The best way, is to take a small piece of waste and tie it to a strong thin stick, saturate the waste with soap or acetic acid, pass down inside of the glass, then blow through with steam and the glass will be clean as new. Never touch the inside of a glass water gauge with wire, if you do, it will crack. The best glasses are the Scotch brand, called Eureka.

Q. If your gauge cock, or a small pipe in the large steam pipe, should happen to get broken off, what would you do?
A. Make a hard wood plug and drive it in with a heavy hammer, then leave it so until it could be repaired, by cutting out the old piece, re tapping and putting in another pipe or gauge cock, whichever the case may be.

Q. What clearance should a boiler have?
A. It should have from three to four inches at the fire line, and from five to seven inches between the shell and bridge wall; a boiler should have from two to three bridge walls so the fire will hug the boiler; it also makes the coal burn cleaner and steams easier. The first bridge wall should be on the back end of the grate bars, and others about three to five feet apart, according to the length of the boiler. Where the smoke returns through the flues, it should be about1/5 larger than the area of flues or tubes combined, bridge walls should lean toward the back.

Q. How should a boiler rest and what on?
A. The front end of the boiler should rest on the fire front, and the back end generally rests on a cast iron leg or two or three rollers, to allow the boiler to expand equally. The mud drum should always hang free under all circumstances.

Q. In what should engineers be careful and exercise good judgment?
A. Engineers should be careful in starting or stopping an engine with a high pressure of steam.

Q. Why should engineers be careful in starting or stopping an engine?
A. Because the rent in giving the steam in starting, and the sudden check in stopping, may cause such a pressure as to rupture the boiler.

Q. What else should engineers look after?
A. Engineers should see that their draft is not choked by ashes under the boiler, and that the outside of the boiler and inside of flues are kept clean, then they will have no trouble in keeping up steam.

Q. How would you clean the flues or tubes of a steam boiler?
A. By either blowing steam through them or using a flue cleaning brush.

Q. How are flues or tubes cleaned by steam?
A. Some boilers have a 1? inch pipe with a valve attached, also branch pipes of smaller dimensions, leading from the 1? inch pipe into the back end and into the flues; others have a hose attached to the front end leading from the steam drum, so the flues can be blown out from the front end. (Cleaning by the brush is the better and more popular way.) Yes, but not practically.

Q. How much pressure would you allow?
A. About 10 or 20 pounds.

Q. Why not more pressure?
A. Because the heat would be so great that the expansion and contraction would not be equal; consequently, the boiler seams would probably leak and the boiler be injured. The better way is no steam pressure.

Q. What benefit is gained by letting the water stay in the boiler until you are ready to clean it out?
A. The mud is kept soft and the scale is not caked to the shell or tubes; also, the seams and the boiler are not injured by unequal expansion and contraction.

Q. How should man and handhold plates be taken out and put in?
A. They should be marked with a chisel at the top, also the boiler at man-hole and hand-hole, whichever it might be, and they should be put in the same way they came out.

Q. How would you gasket the man hole or hand hole plates of a boiler?
A. With pure lead rings; some use sheet rubber, etc.

Q. Why are man hole and hand hole plates made oblong instead of round?
A. Because if they were round they could not be taken out or put in, and a man could not easily enter the boiler.

Q. When filling a boiler with cold water, and raising steam, what should be done?
A. A valve should be left open.

Q. Why do you leave a valve open?
A. Because a boiler fills easier and quicker, and in raising steam the cold air is let out, which allows equal expansion, as cold air prevents equal expansion.

Q. How would you set a boiler?
A. By using a spirit level across and along the flues, allowing the end furthest from the gauge cocks ? inch lower for every 10 feet in length.

Q. Why?
A. Because when there is water in the gauge cocks, there will surely be water in the other end.

Q. How many gauge cocks has a boiler?
A. Generally three.

Q. Where is the first?
A. Two inches above the flues, and the rest two inches apart.

Q. Where is the water line?
A. First gauge.

Q. Where would you carry water when running?
A. Second gauge.

Q. Where would you carry water when shutting down at night?
A. Third gauge.

Q. Why?
A. To allow for evaporation and leakage.

Q. Where is the fire line of a boiler?
A. In line or little below first gauge.

Q. When you open a boiler and look in, where do the scales form and lay thickest?
A. Over the fire-plates and around the mud drum leg or blow-off pipe.

Q. Why?
A. Because the circulation and the heat are greatest there.

Q. What is a steam drum for?
A. To have more steam in volume.

Q. Which is the hotter, coming out of the same boiler, steam or water?
A. They are the same, only water will retain the heat longer, as water is a fluid and steam a vapor.

Q. How should the circulation and feed be?
A. The circulation and feed should be continual.

Q. Why?
A. Because boilers have exploded just as the steam valve was opened to start the engine, after having stood still for some time. This is generally caused by the plates that are in contact with the fire becoming over heated, as the circulation being stopped after the steam is shut off. And just as soon as the valve is opened the pressure become lessened, and the water on the overheated sheets flashes into steam of GREAT ELASTIC FORCE, and if the boiler is not strong enough, a terrific explosion is the result.

Q. If you tried the gauge cocks and found no water in sight, what would you do?
A. Simply shovel wet ashes over the fire, pull it out, raise the flue caps and let the boiler cool down.

Q. Why do you throw wet ashes over the fire before pulling it out?
A. If the fire was stirred up it would create more heat and be liable to burn the plates.

The braces in the boiler should be examined to see if they are loose, also the sheets, flues, heads and seams, to see if they are cracked or leaking; if they are not attended to, they may cause trouble and loss of life and limb. Engineers should not allow anything about the engine or boiler room to become greasy or dirty, for it shows poor management, and a careless, worthless engineer. If valves or cocks leak, they should be ground in with emery and oil until a seat or true bearing is found. Ground glass is good for grinding brass valves.

Q. When should the boiler seams be caulked?
A. When the boiler is empty and cold, for when the boiler is hot and filled with water, the jarring while caulking would have a tendency to spring a leak somewhere else.

Q. Would you call pressure and weight the same?
A. No.

Q. Why?
A. Because pressure forces in every direction, while weight presses down.

Q. Which is best, the riveted or the lap welded flues?
A. The lap welded flues, as they are a true circle and not so easily collapsed as the riveted flues.

Q. Why?
A. Because the riveted flues are not a true circle.

Q. What is foaming?
A. Foaming is the water and steam mixed together.

Q. What causes foaming?
A. Dirty, greasy, oily and soapy

Q. How often would you clean out the flues and when?
A. Once a day, in the afternoon, sometimes in the morning after raising steam.

Q. What different strains has a boiler?
A. To the flues or tubes it has a crushing strain, to the shell a tearing strain.

Q. What causes boiler explosions?
A. There are various causes, such as low water, over-pressure of steam, bad safety valve, foaming boilers and burnt sheets.

Q. Why would a foaming boiler cause an explosion?
A. It generally raises the water from the heated sheets. They become hot; the water falling back on them they crack, and sometimes cause an explosion. A blistered sheet or a scaly boiler will also cause an explosion, by allowing the sheets to become burnt and weakened; also an untrue steam gauge is very bad.

Q. What are the worst explosions?
A. The worst explosions are caused by high pressure and plenty of water; low water allows the iron to burn and crack, which weakens it, and when the cold water touches it, it does not take so much to burst.

Q. How would you know if your boiler had blistered sheets or was rotten?
A. By the hammer test; by taking a small hammer and going inside and outside of the boiler and seeing if it is all right by sound.

Q. How would you know by sound?
A. By the different sounds it has; if it rings and sounds solid it is all right; but if it sounds dead, hollow, or blunt, there is something wrong.

Q. Would you strike the iron hard?
A. Yes, pretty hard.

Do not hesitate to have a boiler insured, as insurance is generally accompanied by hammer test and intelligent inspection, which guarantees safety to the engineer or owner.

Do not reject the advice or suggestions of intelligent boiler inspectors, as their experience enables them to discriminate in cases which never come under the observation of men who do not follow inspection as a business.

Q. If you wished to put a patch on a boiler what kind would you put on?
A. A hard patch; it is reliable and safe.

Q. Why not put on a soft patch?
A. Because they are not reliable and are dangerous.

Q. What is the difference between a hard and soft patch?
A. A hard patch is a patch where the piece is cut out of the boiler and rivet bands are drilled or punched through, then the patch is riveted on, chipped, caulked and made water and steam tight.

Q. What is a soft patch?
A. A soft patch is put over the plate that needs patching, and put on with 5/8 or ? inch countersunk screw bolts, and a mixture of red lead and iron borings to put between the patch and boiler; the piece of sheet in the boiler is not cut out for a soft patch as in a hard patch, consequently the patch is burnt, as the water in the boiler can not come in contact with the patch.

Q. Which are the better, drilled or punched holes?
A. Drilled holes.

Q. Why?
A. Because the fiber of the iron is not disturbed as in punching; in drilling, the iron is cut out regular; in punching, it is forced out at once.

Q. What should be the proper rivets for certain sized sheets, and how far apart?
A. The rivets should be 5/8** and ? inch diameter, and 1? to 2 inches apart.

Q. Before shutting down at night, what should be done?
A. Pull out the fire, pump up to the third gauge and close the glass gauge cocks, so that in case the glass should happen to get broken during the night, the water could not escape.

Q. What would you do the first thing in the morning on entering the boiler room?
A. See how much water was in the boiler by trying the gauge cocks, then open the glass gauge valves, and start the fire to raise steam.

Q. Why do you try the gauge cocks, and not trust to the glass gauge?
A. Because the water pipe connecting the glass gauge with the boiler is liable to become stopped up with mud, consequently the glass would not show a true level of water. The glass gauge should be blown out five or six times a day, to insure safety, but never depend on the glass gauge alone.

Q. If you found too much water in the boiler during the day, what would you do?
A. Open the blow off valve and let out water to the second gauge. An engineer should be very careful when blowing out water when he has a hot fire in the boiler furnace, as the water leaves very fast, and may blow out too much; good judgment should be used.

Q. How would you clean a boiler?
A. First see that there is no fire under the boiler, then let out all the water through the blow off valve, take out the man, hand, and mud drum plates; then take a short handle broom, a candle or torch, a small hand pick, a scraper made out of an old file flattened on the end and bent to suit, also a half inch square iron twisted like chain, about three feet long, with a ring at each end to answer for a handle; place the chain around the flue and work the chain to get the scale off the bottom of the flues; use the pick and scraper to pick and scrape off all that can be seen on top of the flues and the bottom and sides of the shell; then wash out Sinto the mud drum; clean out and put in the mud drum and hand-hole plates; fill up to top of flues; then put in the man hole plate, and fill up to the second gauge ready for raising steam.

Q. Could a boiler not be blown out?
water; salt water forced into fresh water, also too much water and not enough steam room, will cause foaming.

Q. What is priming?
A. Priming is the lifting of water with steam, such as opening a valve suddenly, and drawing the water from the boiler to the cylinder of the engine.

Q. What would you do in that case?
A. Close the throttle valve and leave it closed for a few minutes, then open the valve slowly; that will remedy it. Sometimes priming is caused by too much water and not enough steam room; in that case carry less water.

Q. Are boilers sometimes injured by the hydraulic test?
A. Yes, if tested by an inexperienced person. The hydraulic test is the safest, because if the boiler is bursted no one is likely to get hurt. Never use steam pressure under any circumstances for testing.

Q. If you had a high pressure of steam, and water was out of sight, would you raise the safety valve to let off the pressure?
A. No, under no circumstances.

Q. Why not?
A. Because it would cause the water to rise, and when the valve closed the water would drop on the heated parts and be liable to cause an explosion.

Q. If your boiler was too small to keep up the amount of steam required, would you weight down the safety valve to carry a higher pressure?
A. No.

Q. Why not?
A. Because it would show carelessness and a violation of the laws. There is no mystery about boiler explosions. They are simply caused by carelessness, and no man has the right to endanger the lives and property of others when he knows that he is incompetent to perform the duty required of him as an engineer, whether licensed or otherwise.

Q. How much space should there be between the tubes of a steam boiler?
A. The space should be one-half the diameter of the tube itself.

Q. Can you name the principal valve on a steam boiler?
A. Yes. The safety valve, by all means.

Q. Where should the lower gauge cock be placed in an upright boiler, any size boiler?
A. One third the distance from the top, between the two flue sheets.

Q. How long a time would you consider it safe to leave the engine room alone without attention?
A. Under no circumstances should the engine or boiler room be left alone.

Q. Why not, when everything is in working order?
A. Because no man can tell at what moment an accident might occur, which if neglected might cause a serious loss of life and property.

Q. What is the boiling point of water?
A. It is 212 degrees of heat.

Q. At what point does water turn into steam.
A. It evaporates at 213 degrees.

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