AT the annual convention of the American Society of Civil Engineers just held in this city, some interesting facts were detailed relative to the durability of water pipe. Mr. Worthen, the newly-elected president of the society, showed a piece of wrought iron conduit put in at Lowell in 1845, which carried water continuously till 1881, and since that time to date had been full of water right along. The inside diameter of the pipe was twentyseven inches, and the center of pipe six and one-half feet below surface of ground, laid in dry sand about eight feet above low water in the river. Head of water about twenty-five feet. The specimen shown was one of those taken out when recently making some new fire connections. The pipe was protected with coal tar on the outside. The condition of the pipe was splendid. Nothing had ever been done to it since it was laid, and the sample was attested by Mr. Worthen to be no better than inspection of the pipe now in place indicated the whole to be. Similar testimony was borne by Messrs. Worthen and Francis to the present condition of an eight-foot pipe, put in by Mr. Francis in 1846, to which nothing had been done since that date. This latter conduit averaged from three-eighths to five-eighths inch in thickness, according to pressure.

In both these conduits, at the advice of an eminent chemist of the day, Samuel M. Dana, a piece of zinc, #bout two inches by four, and one-half inch thick, had been riveted by a single rivet to each of the plates or sheets constituting the pipe, and this was believed to have its effect in preventing internal corrosion of the pipe. The Merrimac river water was, under certain circumstances, declared to have a pronounced corrosive effect, ordinarily at 120 degrees Fahr. (a common temperature of the water), taking hold of the iron with great rapidity.

Mr. Francis stated that at Lowell, pipes put in in 1829 to stand a pressure of ahead of 150 feet, were still in use under a head of 100 feet. They are very much obstructed by rust on the inside, but there is nothing that affects the strength of the pipe. These pipes were obtained from Philadelphia about 1829; they are castiron pipes of eight inches diameter.

Mr. Graff referred to a remarkable phenomenon relating to the seven-foot pipe crossing High Bridge. The pipe is pipe having lap joints on the outside. It is a butt joint with a lap of some considerable width on the outside. In walking through the conduit Mr. Graff reports that he could detect every one of these lap joints by its freedom from corrosion. These laps on the outside were from eight to twelve inches wide, and wherever they occured there was almost entire freedom from corrosion, while on the rest of the pipe there was very considerable corrosion. It was a smooth pipe inside—a wrought-iron pipe.

General Greene said zinc had been tried in the case Mr. Graff cited, but he did not know that any good resulted from putting the zinc in. Mr. Greene then referred to some experiments made on the Croton aqueduct across Glendenning avenue in the city, which has now been taken down. There was a viaduct of five or six arches or more, and over these arches Mr. Jarvis had put about one-half inch of cast iron plate together, coming up the sides about four feet, the height he expected the water to be used in the aqueduct. General Greene had seen that taken down after it had been there, some thirty or forty years, and it was not in the least oxidized. In some places there were only four inches of brick. This iron was as bright as when first laid down. Mr. Greene did not know why wrought-iron pipes could not be protected to the same extent by giving them a little more diameter and lining them with cement, or brick laid in cement. The lime present in the cement prevents the oxidation of the iron.

Mr. Graff pointed out that the corrosion of cast-iron pipe would be affected largely by the soil through which it goes. He had on one occasion an opportunity of seeing this in two miles of pipe that were taken up after having been in the ground at that time fiftytwo years. These pipes were laid through every soil that exists in Philadelphia, from gravel to shore sand. Those pipes that were in the shore (dry) sand had the founder’s mark upon them and their original blue skin. Externally they were as good as the day they were laid. There were no means of distinguishing them from the pipes laid the day before; while those in gravel were very considerably corroded. Another opportunity of observing this was had by storing these pipes in an open lot. Those first spoken of, those having been in the sand, were good enough to be laid again, while those that had been in the gravel soil fell to pieces during the winter. Clay soil was found somewhat of a medium between the two, but very much better than the gravel, since the moisture, if it obtained at all, would remain or the condition would not vary from wet to dry.

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