Category:725 Metal Pipe and Pipe-Arch Culverts
725.1 Construction Inspection for Sec 725
|Metal and Concrete Pipe|
|See also: Research Publications|
725.1.1 Shop Elongation
Strutting or shop elongation is used to provide slight vertical distortion of metal pipe. This improves resistance to vertical loads imposed by embankment. If field strutting is employed, inspection personnel should be very cautions and stay well clear during installation and removal of vertical struts. Loading is heavy and operations are dangerous. For this reason most pipe is now ordered shop elongated.
Pipe shall not be dragged over gravel or rock and shall be prevented from striking rock or other hard objects during placement on bedding. Pipe with protective coatings shall be handled with special care to avoid damage. Pipes on which such coatings have been damaged shall, unless repaired to the satisfaction of the engineer, be rejected. During backfilling, keep stones or broken concrete well away from the pipe. It is important that backfill be kept near the same elevation on both sides of the pipe to prevent distortion or displacement. This becomes more critical as pipe diameters increase and is particularly critical on pipes which have been vertically elongated.
Final measurements are not required except for authorized changes which will be added to or deducted from plan quantity. The inspector should note in the diary when the culverts were built and note that they were built according to plan or approved changes.
An inspection of all new installed pipe should be made. It should be tested for the criteria set forth in the Inspection heading in the spec. book for the applicable pipe. The inspector should make sure the pipe is from an approved source and is properly marked. The inspector should not accept any pipe that does not have a MoDOT pipe identification number listed on the bill of lading. Please note, each type, size, class, etc. of pipe on the bill of lading should have a unique MoDOT identification number. Concrete and metal pipe are inspected at the plant by District Construction and Materials. Plastic pipe is sampled at the project. District Construction and Materials should be contacted when the material arrives on site. Care should be made so that sampling does not leave the contractor short of certain sizes and length of pipe. Both concrete and plastic pipe should have an industry quality control stamp ie. ACPA or PPI. There will not be a MoDOT OK stamp. Tape measures or other devices can be used for a preliminary measurements for diameter deflection. If the results are in question the mandrel test will serve as the definitive test for deflection. Always make sure that when testing the right measurement unit is used. Pipe can be produced in either English or Metric units. Make sure the measurements are taken in the same units as the pipe was produced. The Qualified List for each type of pipe will indicate the manufacturer's identification mark and the units (English or metric) that was used to fabricate the pipe.
725.2 Material Inspection and Laboratory Testing for Sec 725