Making Repairs to Pipe Under Pressure
Newark, N. J., Water Bureau Repairs 36-lnch Steel Pipe Line by Electric Welding, While Under Pressure of Ninety Pounds — How the Work Was Done and Its Cost
THE following account of repair work accomplished by the bureau of water of Newark is doubly interesting as illustrating the method adopted by Mr. Foulks in performing the electric welding of the steel pipe and in the fact that the work was done while the pipe was under 90 pounds water pressure. As Mr. Foulks has had considerable experience along these lines he speaks with some authority on the subject.
The city of Newark in 1891 laid 26 miles of 36-inch and 48-inch riveted steel pipe, and in 1904 laid a second and third line 28 miles in all, of 42-inch, 48-inch and 60-inch riveted steel pipe. Up to the present time the only difficulties encountered have been where the two lities extend through a peat swamp; at this point electrolytic action has taken place, due to stray currents from trolleys, or to local action in the soil. The pipe has become pitted badly in places, as shown in Fig. 1 and from time to time these pits have given way, causing small leaks, which have been repaired temporarily as follows: by plugging the holes with pine plugs, which were braced with concrete when the holes occurred on the side or bottom of the pipe; by capping the plug with a lead cover, which was held in place by braces extending to the sides or bottom of the trench; or by pulling steel bands in place with bolts and running lead between the pipe and the bands.
Electric Welding Gave Good Results
While the methods used have answered the purpose up to the present time, they are makeshift, and it has been necessary to look for a better and more permanent repair or replace certain sections of the line. As I have had considerable experience in using electric welding for making other repairs that were somewhat similar, I decided to give it a trial on this work, and produced excellent results on the 36 inch line laid from Belleville Reservoir to the 60 inch feeder on Bloomfield Avenue, running through the swampy section mentioned above.
Repairs Made With Pipes Under Pressure
At this point the thickness of the pipe, which carries a pressure of 90 pounds, is 5/16 of an inch. The pipe sprung a leak which showed up on the surface and it was uncovered in two sections for a distance of approximately 10 and 15 feet, respectively, and repairs were made without shutting off the water or reducing the pressure. After thoroughly cleaning the pipe it was found to be pitted badly and a hole approximately 3/8 of an inch in diameter was plugged with a pine plug. The plug was then cut off with a hacksaw flush with the surface of the pipe and covered with a metal cap, held in place by tacking it on the sides by means of the electric arc.
The cap used consisted of metal of approximately No. 11 gage, obtained from punchings, and was slightly concave. Metal was then welded over this cap, extending far enough over the edges to get a firm hold on the pipe. All the pits were filled and reinforced by welding and a triangular patch of about 9 inches on each side was welded over a number of pits which occurred in one spot. The pipe was then recoated, making a permanent job, (See Fig. 2).
Two Sections of Line Welded
Two sections of the line were welded in this manner and the following costs were kept:
2 men, 8 hours $12.50
1 laborer, 8 hours 4.56
steel, gas, oil, etc. 2.10
This makes an average cost of .77 cents per lineal foot for repairing and reclaiming the pipe in this section.
These costs do not take into account the cost or depreciation of the machine—a gasoline driven arc welding set, mounted on a Ford chassis, consisting of a 4-cylinder, 4-cycle, vertical type engine, direct connected bv flexible coupling to a 200 ampere constant energy type selfexcited arc welding generator, with inherent regulations, complete with panel for current regulated steps from 75 to 200 amperes; nor do the costs include excavating and backfilling, which would have to be made in case of any repair or replacement. The condition of the pipe on the sections welded was very bad and the costs for doing the work were maximum as the men were not thoroughly familiar with this class of repair. If cast iron had been used under the same conditions these lines undoubtedly would have deteriorated under the electrolytic action and it would have been impossible to repair them by electric welding.
Life of Steel Pipe Underestimated
It was estimated when the Newark lines were laid in 1891 that the probable life would be approximately 30 years. When the 60 inch line was laid bids were received for both steel and cast iron, and it was found that the difference in cost between the steel and cast iron was so great that the steel line could be renewed in 13 or 14 years for the difference. The records up to the present time in reference to the life of steel lines are not as numerous as they are for the cast iron lines, but there is ample proof to show that the life of steel lines is very much underestimated in a great many cases, as lines have been in service for a period of 40 or 50 years that are still in excellent condition.