Proper Steel Water Pipe Installation
Excavating The Pipe Trench
The pipe trench should be excavated as per the plans and specifications for the project. The bottom of the trench should be prepared which typically requires up to 6 inches of select bedding material. The bedding material, as required, should be spread evenly so that it will provide support for the pipe along its entire length. Bell holes should be formed in the trench bottom. The backfill material in the pipe zone is to be free from organic material, boulders, and rock or stones in excess of 3 inches and any other unsuitable materials as described in the specifications for the project.
Lowering The Pipe
Pipe should be lowered into the trench with the proper machinery using slings and guide ropes that will prevent damage to the pipe and its coatings. Care should be exercised to prevent the pipe from dropping or landing hard in the bottom of the trench. Foreign materials should be removed from the pipe, bells and spigots and care should be exercised to prevent material from entering the pipe while it is laid in the trench. To avoid debris entering the pipe from the excavation, trenches should be dewatered for proper installation. Pipe should be lowered bell first which will allow the edge of the bell to overlap the spigot. Bell and spigot should be insertion to the proper depth which is indentified by a “stab mark”. After the joint has been engaged, ensure that the gap is distributed evenly around the pipe. Assure that the joint is at or within the proper deflection limits. Generally speaking, lap weld joints 16 inches and larger shall not be deflected in excess of ¾ of an inch in any direction (horizontally or vertically).
Bedding And Backfill
Bedding and backfill should be placed around the pipe making sure that it has been densified equally around the pipe up to the point specified in the plans for the project. The backfill should be placed around the pipe in lifts that are suitable for compaction. The density of the soil surrounding the pipe shall be as specified in the specifications for the project. Density values are usually specified as 85 to 95 percent standard proctor density. When installing pipe 36 inches and larger, a probing rod should be used to provide adequate compaction in the area between the spring line and the pipe invert elevation. Material should be placed in a manner that prevents the pipe from being displaced or altered in elevation. Generally speaking backfill around the pipe should be placed by hand, shovel sliced, and pneumatically tamped and carefully compacted.
Backfill the trench above the bedding zone with the material specified. Compact to the minimum density required by the specification.
Once the trench has been backfilled it should be checked for initial deflection. This can be accomplished by cutting a rod to the proper length and inserting it vertically in each pipe in at least 3 areas. Any pipe found to be over deflected, should be exposed and backfilled again until it is within the specified limits.
Please call your Jindal Field Technician, Project Manager, or Sales Representative for any additional information or assistance you may have concerning proper pipe installation.