Glossary

Aggressive Water Corrosive water. A term'generally applied to water determined to be corrosive by Langelier and Ryznar indices. Characterized by low calcium, total dissolved solids and alkalinity. Also, water having a high CO2 content.

Annealing Treating metal by carefully controlled heating and cooling to remove internal stresses and bring about the desired microstructure.

Ball Impression Test A quality control test in which a steel sphere is pressed under load into the interior surface of the spigot of each ductile iron pipe length. A suitable resulting indentation is an indication of proper ductility.

Carbidic A term applied to iron carbide (also called cementite), a hard brittle constituent of ductile cast iron before annealing.

Cantilever A beam securely fixed at one end and unsupported at the other end.

Cathodic Protection A system of protecting a metal structure from corrosion by using it as the cathode of a cell along with sacrificial or impressed current anodes.

Ductility The ability of a material to be plastically deformed by elongation, without fracture.

Elongation The amount of permanent extension in the vicinity of the fracture in a tensile test. Expressed as a percentage of original gauge length.

Ferritic A term applied to the microstructure of ductile iron. Ferrite is the micro-constituent that surrounds the carbon (graphite) spheroids in ductile iron. It contains up to 2.4% silicon which improves strength and wear resistance of ductile iron.

Holidays Discontinuities in coatings or linings, including pinholes, pits, or voids.

Hydrostatic Test A quality control test in which each pipe is subjected to an internal water pressure and observed for leaks or the inability to withstand the pressure.

Leaching Test A quality control test for seal-coated, cement-mortar lining in which the lined pipe is exposed to distilled or demineralized water for three successive 24-hour periods. At the end of each period, the water is tested and no more than 25 ppm of hardness or alkalinity may he imparted to the water

Long-Line Current The accumulation of direct current on a long, electrically continuous pipeline due to differences in the electrical potential of soils along the pipe.

Mil One one-thousandth inch (.001 in.)

Negative Pressure A way of expressing a vacuum or partial vacuum.

Notched Charpy Impact Test A quality control test (ASTM-E23) in which a notched metal strip from the wall of ductile iron pipe (0.5" x 0.4") is impacted with an anvil (at a temperature of 70° F ± 10°) and must have an impact resistance of at least 7 ft.-lbs.

Pearlitic Iron A lamellar aggregate of ferrite and cementite (iron carbide) in the microstructure of iron. This is an intermediate condition of ductile iron in the annealing process. When compared with ferritic ductile iron, pearlitic iron has higher yield and ultimate tensile strengths but lower elongation and impact resistance.

Permeability (Perm) The ability of a membrane or other material to permit a substance or gas to pass through it. Perm is a unit indicating the degree of permeability.

Spheroidal/Spherulitic The spherical form of crystallized graphite in ductile iron.

Stray Direct Current Direct electrical current emanating from sources such as cathodic protecting systems or d.c. powered industrial or transportation equipment and traveling through the earth. Under certain conditions, it can enter and depart from underground metallic structures, thereby causing corrosion.

Tensile Test A quality control test for ductile iron pipe. A specimen machined from the mid-section of the pipe wall is placed under tensile load (ASTM E8 procedure). Yield and ultimate strengths are recorded along with percent elongation.

Torque Rotation moment or force as applied by a wrench to a nut in tightening the nut on a bolt.

Tuberculation/Red Water Results of corrosion of iron or steel pipe by aggressive water. Tuberculation is a collection of corrosion products that stifles the free flow of water through the pipe. Red water may be caused by rust (oxidized iron), also a result of corrosion.

Ultimate Tensile Strength The stress on a tensile test specimen at the time of fracture.

Water Hammer Pressure rise in a pipeline caused by a sudden change in flow velocity.

Yield Strength The stress at which a tensile strength test specimen exhibits a specific deviation from the normal stress-strain proportion.

Suggested Sample Specifications For Ductile Iron Pipe & Fittings For Water And Other Liquids

Ductile iron pipe shall he designed in accordance with the latest revision of ANSI/AWWA C150/A2 t.50 for a minimum 150 psi (or project requirements, whichever is greater) rated working pressure plus a 100 psi surge allowance (if anticipated surge pressures are other than 100 psi, the actual anticipated pressure should be used); a 2 to 1 factor of safety on the sum of working pressure plus surge pressure; Type       laving condition and a depth of cover of       feet.

Ductile iron pipe shall be manufactured in the U.S.A. in accordance with the latest revision of ANSI/AWWA C 151/A21.51. Each pipe shall be subjected to a hydrostatic pressure test of at least 500 psi at the point of manufacture.

Pipe shall have standard asphaltic coating on the exterior. Pipe shall also have cement-mortar lining on the interior in accordance with ANSI/AWWA C104/A21.4, of latest revision.

The class or nominal thickness, net weight without lining, and casting period shall be clearly marked on each length of pipe. Additionally, the manufacturer's mark, country where cast, year in which the pipe was produced, and the letters 'DI" or "Ductile" shall be cast or stamped on the pipe.

All pipe shall be furnished with Push-on Type joints, such as Tyton® or Fastite®. Joints shall be in accordance with ANSI/AWWA C111/A21.11, of latest revision, and be furnished complete with all necessary accessories.

Fittings shall be ductile iron. Ductile iron fittings shall conform to the latest revisions of either ANSI/AWWA C111 10/A21.10 or ANSI/AWWA C153/A21.53. Fittings shall have a standard asphaltic coating on the exterior. Fittings shall also have a cement-mortar lining on the interior in accordance with ANSI/AWWA C104/A2L.4, of latest revision.

Fittings and accessories shall be furnished with either Push-on or Mechanical Type joints in accordance with ANSI/AWWA C111 111 111/A21.11, of latest revision.

All pipe, fittings and accessories shall be installed and tested in accordance with the latest revision of ANSI/AWWA C600. Newly installed ductile iron water mains shall be disinfected in accordance with the latest revision of ANSI/AWWA C651 prior to placing in service.


<< Previous