These various costs gave the following results for small size pipe:
| —Cost per foot for— | ||||
| 6-in. pipe. | 8-in. pipe. | 10-in. pipe. | 12-in. pipe. | |
| Cement | $0.057 | $0.073 | $0.099 | $0.128 |
| Sand | 0.006 | 0.008 | 0.011 | 0.014 |
| Labor | 0.019 | 0.019 | 0.026 | 0.034 |
| Hauling | 0.024 | 0.032 | 0.044 | 0.056 |
| Laying | 0.024 | 0.024 | 0.032 | 0.042 |
| Trench | 0.020 | 0.020 | 0.020 | 0.020 |
| ——— | ——— | ——— | ——— | |
| Totals. | $0.15 | $0.176 | $0.232 | $0.294 |
The above costs show that the pipe in place costs about twice as much as pipe in the yard, even with cement at $4.45.
Fig. 270.—Bordenave Pipe for Swansea, England, Water Works.
MOLDED PIPE WATER MAIN, SWANSEA, ENGLAND.—As a good example of foreign practice in molded pipe conduit work a water main constructed at Swansea, England, has been selected. This pipe line had to operate under a head of 185 ft.; it was constructed under the patents of the French engineer, Mr. R. Bordenave, who has built many miles of the same type of conduit on the Continent.
Fig. 270 shows the construction of the pipe, the drawing being a part longitudinal section through the shell at the joint. The pipe consists of an inner and an outer reinforcement separated by a sheet steel tube and all embedded in a 1-2 mortar. Both inner and outer reinforcements consists of longitudinal bins of cruciform (+) section wound by a spiral bar of the same section wired to them at every intersection. Only the outer reinforcement and the steel tube are considered in calculating the strength of the pipe, the inner reinforcement being considered as simply supporting the mortar.
Fabrication of Reinforcement.—The steel tube is made of 1 mm. (0.04 in.) thick sheets of steel bent to a cylinder and jointed longitudinally by welded butt joints, welded by a blow pipe using acetylene and oxygen. Tests of this welded joint by R. H. Wyrill, Waterworks Engineer, Swansea, showed it to be quite as strong as the unwelded steel cut from the shell. The circumferential joints of the tube were made by turning up the edges of the sheets and welding them; this gives a flexible watertight joint. The tube was made in lengths of 9 ft. 9½ ins. and its ends were turned up all around; just back from the turned-up ends a vertical sheet steel collar was welded to the tube to form a strip end for the external coating. These details are shown in Fig. 270. When the tube for a length of pipe is completed the inside shell reinforcement previously made is slipped into it and the outside shell reinforcement is formed on it as a mandril, as shown by Fig. 271.
Fig. 271.—Applying External Reinforcement to Bordenave Pipe.