In this paper Mr. Forstall advocates the following table to determine the size of connections and the method of making

For drawings and table of dimensions of Hat Flanges and Hub Sleeves, see Appendix at end of paper.

In connecting mains to mains the idea is to use a saddle piece, otherwise called a hat flange, wherever the disparity between the two mains is very great, and the largest so large that a split sleeve with hub cast on would involve heavy cost. As the disparity and the size of the largest main decreases split sleeves are used, and in turn ordinary branches.

16. Cutting Cast Iron Pipe. In cutting cast iron pipe, the pipe should first be marked around the circumference where the cut is to be made. On the larger size pipes an easy way to make the mark so that the pipe will be cut off squarely is to have a piece of sheet metal, card board or heavy paper from 5" to 18" wide and long enough to more than make the circumference of the pipe. This is wrapped around the pipe closely, and the mark for the cut is made at the edge of the cardboard. It may then be cut, using a dog or striking chisel and a sledge hammer. The first cut around the whole circumference of the pipe should be a very light one. This cut should be followed by others around the circumference successively, care being taken that the cut is kept of a uniform depth around the whole circumference of the pipe. As a preventive of cracking some authorities deem it advisable to use a diamond

point chisel to make the first cut, and still others on larger sizes use a diamond point in making the first cut both on the inside and the outside of the pipe. (Simson, Frank Hellen, Franklin.-'03-Q. B., No. 133.)

17.

It seems to be conceded that in making extensions of present mains, the safest way is to leave the connection with the live line until the last. (Ohio Gas Light Assn.-'02-Franklin.) Gas Main Bags. Originally beef bladders were inflated and used for shutting off the flow of gas in mains while connections were being made, but the difficulty in procuring these in a condition to be used led to the substitution of rubber gas bags. There are now a number of patented appliances for this purpose on the market, but the rubber bag is the most universally used. The hole for the insertion of the gas bag should be drilled or cut large enough so that the bag may be inserted into the main without crowding. After the hole is drilled care should be taken to push all cuttings away from where the bag is to be placed so as not to cut the bag. A swab of waste on a stick will accomplish this. A little hard soap may be used to fill up the threads and prevent them from cutting the bag, or, better still, a thin brass spun ferrule of the proper size is placed in the hole and the bag is slipped through the ferrule. A piece of thin sheet gum with a hole through the center slipped over the stem of the bag will aid in making tight. The bag should always be tested and examined before being inserted, and it may be remarked that as much depends upon the proper placing and insertion of the bag as upon how hard it is blown up.

In case any difficulty is experienced in blowing up a bag, it is suggested that a bicycle pump be used for this purpose, care being taken not to force the gas bag too hard. Where there is a very strong flow of gas in the main, it is sometimes found advisable to insert a fork made of heavy wire in front of the gas bag to prevent it from slipping along the main, the prongs of the fork passing on each side of the stem of the bag. In bagging open ends it will be found advisable to use two bags, one in front of the other, so that in case of the failure of one bag, the other will remain tight. When inserting a bag, always have extra help on the ditch to assist the men in the

ditch in case of necessity. Oil or condensation on the bottom of the main has a very deteriorating effect on the rubber used in making gas bags, and they should be wiped clean after being removed from the main.

There is now a canvas covering made which protects the bag. (Q. B.-'05-No. 581.)

When the bags are stored away, they should be washed with lukewarm water, inflated almost full, rubbed with pure tallow and stored in a cool damp place. (McAdam, Shaw.-O. Q. B. -'05-No. 627.)

It seems to be conceded that there is no way of reviving the

rubber in a bag after it has once deteriorated. (O. Q. B.-'05 -No. 628.)

At least it would be unsafe to use gas bags which were in this condition.

There is also a canvas or cloth bag.

The illustration represents a gas bag which has been used for a number of years. The bag is made from cloth usually used for bed sheeting, and cut in the shape described in the enclosed sketch. The bag is cut about 11⁄2" larger than the circumference of the pipe, sewed and turned inside out, and dipped in linseed oil to make it hold water. The bag is placed over the hook (A) and put into the pipe, after which the hook is removed and the 3/4" pipe is fastened to the mouth of the bag. Water is poured into the pipe, and fills the bag and stops the flow of gas. The pipe is supported by a stake, which keeps it in position. To remove the bag, place hand at the mouth and pull out the pipe. Pull slowly on the bag, which will force the bag to the inner or top surface of the pipe and cause the water to rush out in a few seconds. From 2 to 3 lbs. can be created on the bag, depending on the height of the water column, fifteen seconds being necessary to insert the bag and cut off the flow of gas. A 10" bag will bag-off a 10" and 8" pipe. A 6" bag will bag-off a 6" and 4" pipe. A 4" bag will bag-off a 4" to 3" and 2" pipe.

WROUGHT IRON LOW PRESSURE MAINS.

In laying wrought iron mains, the preparation to be made is the same as for cast iron mains, with the exception that it is not customary in laying low pressure natural gas mains to make any provision for taking care of condensation. Consequently, low pressure natural gas mains are not laid to grade. There is, of course, some difference in the tools required for the work. In addition to the ordinary tools required by the laborers for digging the trench, etc., the following tools will be needed by the pipe layers.

Swabs for cleaning out the different size mains. 2 pipe jacks and boards.

4 pair of tongs for each size main to be laid.

2 set of chain tongs.

Diamond point chisels.
Cape chisels.

Machinists' hammers.
Crowbars.

OW.S. Co.

The lay tongs are pipe tongs made on purpose for this kind of work.

They have very long handles, are made heavy, and the bit is slipped in place and held by a wedge. The bit has four sides, and when one becomes dull the wedge is driven out and the bit turned so as to give a fresh edge for biting the pipe. The chain tongs are used on the fittings.

19. Dopes Used. In addition to the tools some dope for use on the threads is required. In natural gas work a black asphalt varnish seems to have the preference, but the following mixtures have been recommended:

1-3 raw linseed oil and 2-3 Portland cement.

Graphite and lard oil.

Graphite and linseed oil.

Graphite and cylinder oil.

Equal parts of red and white lead mixed with linseed oil.

Of the mixtures the one consisting of Portland cement and raw linseed oil seems to have the preference, and is the most practical. (O. Q. B.-'05-No. 560.)

20.

Wrought Iron Pipe. In the pipe used for this purpose, preference is given to wrought iron over steel, as the wrought iron pipe is not as much affected by corrosion as is steel pipe. It is softer and more easily tapped for service connections, and is more apt to be even in quality. The mills make a special grade of pipe for this purpose called line pipe. This pipe is about 10 per cent. heavier than the ordinary pipe and the thread