A 35-MILE FIRE PROTECTION LINE

A 35-MILE FIRE PROTECTION LINE

Extension to Philadelphia Hi^h Pressure Service—Accepted After Severe and Unusual Tests—Results Obtained and Service Given Satisfactory

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16-Inch Universal Pipe Line on Allegheny Avenue, East of Kensington, Philadelphia

WATER waste surveys have frequently revealed heavy leaks in mains and laterals where least suspected so that it may be concluded that a pipe line can never be any better than its foundation. In other words, the value of a pipe line depends upon the integrity of its joints and where they are of the ordinary bell and spigot type, these joints can be no better than the foundation that supports them. Unfortunately, there is also another element to be contended with and that is shock from water hammer. As is well known, the force which must be absorbed by the joints from this cause is often very great so that where frequently repeated, some of the joints at least are bound to lie started. The initial leak thus caused increases in time, often growing very quickly, and undermines the pipe line at that point with the result that its weight is no longer supported and it sags at the joint, resulting in a greatly increased volume of water escaping through the opening.

In one instance that was revealed by a Pitometer Survey of New York City some years ago, a striking instance of this kind found on the East River front was discovered to be responsible for loss of three million gallons a day. This leak had been running so long that it had come to be considered as an underground stream by those in the neighborhood. In another case in Mt. Vernon. a similar leak was responsible for the appearance of what was considered to be a spring in a field a block or more away and lower down. The presence of the spring proved an inducement to a purchaser of the property, who sued to have the contract annulled when the water works company remedied the leak and the spring disappeared.

These instances are typical of many that could be cited in various parts of the country. If such serious losses as these occur under the usual low average pressure, it will be apparent that little reliance could be placed upon a pipe line with this type of joint for a high pressure fire system.

In such a line, a small initial leak w’ould increase so rapidly under the high pressure that a large area would be washed out and considerable property damage done. As it is naturally out of the question to provide a bed rock, or a heavy concrete foundation throughout its entire length for a pipe line, the joints must be of such a character that they are not affected by high pressure, water hammer, or deflection of the line itself even to an extent where the foundation of one or more entire lengths fails. A high pressure fire line in which the joints were not proof against these causes of leakage as well as contraction and expansion, would hardly merit the name.

Consequently when the engineers and officials in charge of the Philadelphia high pressure service contemplated an extension to the system, the first problem they tackled was that of selecting a type of joint upon which the same degree of dependence could be placed as upon the line itself. Tests were accordingly devised to. which all of these types of joints were subjected, to demonstate the degree to which each one of them could withstand the causes of leakage already mentioned. The original high pressure system consisted of heavy flanged pipe. With a view to the adoption of the best type for the high pressure extension, samples of the bell and spigot type, the flanged type and the Universal joint type were subjected to exhaustive tests. The result of the latter eliminated the bell and spigot joint from further consideration so that specifications were drawn to cover either the flange or the Universal type and the contract was awarded for approximately 35 miles of the Universal high pressure cast iron pipe and fittings, ranging in size from 8 to 20 inches diameter.

Supt. John W. Weaver of the Philadelphia High Pressure Fire Service made some interesting tests in the presence of Director of Public Works, Mr. Stearns, Mr. Dunlap, Chief Bureau of Water; Chas. Hexamer, Chairman, Local Board of Fire Underwriters; John C. Trautwine, Consulting Engineer and Chjef Baxter, Bureau of Fire.

Of especial interest were the deflection test and strength of line test, which were successfully passed by Universal Pipe. These tests were covered by Superintendent Weaver in a report to Director Stearns and excerpts from this report follow:

“Nine lengths of 12-inch Universal Pipe, each length 6 ft. long, were connected and the entire pipe length, amounting to 55 ft. 1 ⅛ inches was blocked up 12-inch from the floor. A water pressure of 300 lbs. per sq. inch was applied to the pipes and the same was minutely examined for detects (none were found). The line was then subjected to greater pressures with results as follows :

At 400 lbs. pressure the entire blocking was knocked from under 7 lengths (42 ft.) of the line thus allowing the line to assume the form of a parabola through its own weight plus the weight of water in the pipes. The line settled 4 inches in the center of the 42 feet suspended and while in this suspended condition carried pressure of 400 lbs. for 10 minutes showing no defect whatever. With the pressure still on the pipe was blocked up to original position and measurement of the line was the same as when under 300 lb. pressure, 55ft. l-⅜ inches. No defects of any kind developed throughout the entire test. The test proved that each joint had borne its proportionate share of expansion and strains.

Parts of the summary of the report stated, “Investigation shows conclusively that the universal joint will stand vibration and thrust far better than either flange or lead joints. I cannot impress upon you too strongly that the subjects of vibration and thrust are the most important factors governing the efficiency of any system of pipe line. And further investigation shows conclusively that the universal joint is greatly superior to flanged or bell pipe in taking care of these important factors. As to conductivity of pipe showing its capability of resisting electrolysis, results show pipe suffers little or no effect from this source.”

The Universal Pipe used at Philadelphia was tested to 800 lbs. hydrostatic pressure at the foundry and tested to 400 lbs. hydrostatic pressure in the trench. The trench test was made with no joint leakage allowance. This was a very unusual proceeding since in most tests of installed pipe a certain amount is allowed for leakage.

The following data was taken from a report made by John E. Codman, consulting engineer, to Henry Clay, director of public safety :

“In all this number of joints there was but one that showed any signs of leaking and this was simply a slight •defect which was remedied in a few .moments.”

The results obtained and the service as given by this installation is a worthy tribute to the foresight and efficiency of the Philadephia High Pressure Officials in charge. The pipe was installed by the Keystone State Construction Co. of Philadelphia and John II. Morrison and Chas. Schubel represented the Central Foundry Company on the job.

J he installation of a water system at Three Forks, Mont., is said to have reduced the fire insurance rates from the highest in the state to the lowest. It is estimated that the reduction will more than offset the interest on the cost of the new plant.

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