Testing and Inspection

             There are various types of tests used for the installed cast iron soil pipe and fittings. These are water or hydrostatic, air, smoke and peppermint. Proper safety procedures and protective equipment should be employed during all testing procedures. Installers should always consider local conditions, codes, manufacturer installation instructions, and architect/engineer instructions in any installation. 

             A water test, also called a hydrostatic test is made of all parts of the drainage system before the pipe is concealed or fixtures are in place. This test is the most representative of operating conditions of the system. Tests of this type may be made in sections on large projects. After all air is expelled, all parts of the system are subjected to 10 feet of hydrostatic pressure (4.3 PSI) and checked for leaks. Air test :

             Air tests are sometimes used instead of the water or hydrostatic tests of completed installations. Cast Iron Soil Pipe and Fittings joined with rubber compression joints or hubless mechanical couplings are expected to have a reduction in air pressure during a 15 minute test. This drop in air pressure does not indicate a failure of the system or an indication the system will leak water. Because molecules of air are much smaller than water molecules a cast iron system is expected to have a reduction in air pressure during the 15 minute test period. 

            Caution: Materials under pressure can explode causing serious personal injury or death. Extreme care should be exercised in conducting any air test. Persons conducting an air test must exercise care to avoid application of pressure above 6 psig to the system under test by using appropriate pressure regulation and relief devices. Persons conducting the test are cautioned to inspect for tightness of all system components prior to beginning the test and to avoid adjustment of the system while under pressure. Proper protective equipment should be worn by individuals in any area where air test is being conducted.

Test Procedures:

             Water Test - A water or hydrostatic test is the most common of all tests used to inspect a completed cast iron soil pipe installation. The purpose of the test is to locate any leaks at the joints and correct these prior to putting the system in service. Since it is important to be able to visually inspect the joints, water tests should be conducted prior to the "closing in" of the piping or back fill of the underground piping. 

             As water fills a vertical cylinder or vertical pipe it creates hydrostatic pressure. The pressure increases as the height of water in the vertical pipe increases. The Cast Iron Soil Pipe Institute recommends 10 feet of hydrostatic pressure (4.3 pounds per square inch). This is the recommended test by most plumbing codes. To isolate each floor or section being tested, test plugs are inserted through test tees installed in the stacks. All other openings should be plugged or capped with test plugs or test caps. 

             Prior to the beginning of the test, all bends, changes of direction and ends of runs should be properly restrained. During the test, thrust forces are exerted at these locations. Thrust is equal to the hydrostatic pressure multiplied by area. Thrust pressures, if not restrained, will result in joint movement or separation causing failure of the test. All air entrapped in the system should be expelled prior to beginning the tests. 

             Once the stack is filled to ten feet, an inspector makes a visual inspection of the section being tested to check for joint leaks. In most cases, where these leaks are found, hubless couplings have not been torqued to the recommended 60 in. pounds. Proper torquing will correct the problem. If leaks occur during testing of hub and spigot materials the joint should be disassembled and checked for proper installation. 

             Fifteen minutes is a suitable time for the water test. Once the system has been successfully tested it should be drained and the next section should be prepared for test. 

             Smoke Test - When a smoke test is required by engineers, architects, or plumbing codes, it is applied to all the parts of the drainage and venting systems after all fixtures have been permanently connected and all traps filled with water. A thick, penetrating smoke produced by one or more smoke machines, not by a chemical mixture, is introduced into the system through a suitable opening. As smoke appears at the stack opening on the roof, the opening is closed off and the introduction of smoke is continued until a pressure of 1 inch of water has been built up and maintained for 15 minutes or longer as required for the system. Under this pressure, smoke should not be visible at any point, connection or fixture. All windows in the building should be closed until the test is completed. 

             Peppermint Test - Some engineers, architects, and plumbing codes require a peppermint test to be applied to all parts of the drainage and venting system after all fixtures have been permanently connected and all trap seals filled with water. A mixture of 2 ounces of oil of peppermint and 1 gallon of hot water is poured into the roof opening of the system, which is then tightly closed. There should be no odor of peppermint within the building at any point, connection, or fixture as a result of the peppermint mixture having been introduced into the system. Operators who pour the peppermint mixture must not enter the building to do the testing. The peppermint test is usually used in old installations to detect faulty plumbing. 

Thrust Forces:

             Thrust or displacement forces are encountered as the pipe or cylinder is filled with water. The higher the fill the greater the force acting to separate a joint. Table 1 shows the pounds of force tending to cause joint separation when using pipe from 1 1/2" to 10" and a head of water from 10' to 120'.