TAPPING DUCTILE IRON PIPE

Transcription

1 TECHNICAL BULLETIN FOR WATER & WASTEWATER, FIRE PROTECTION

2 P 2 Table of Contents Pipe Thickness Required for Different Tap Sizes 3 Tapping Test Details 5 Test Procedure 6 Observations and Comments 7 U.S. Pipe Products for Water, Wastewater and Fire Protection 8 BRO-035

3 P 3 Pipe Thickness Required for Different Tap Sizes Pipe Size inches No. of Threads Tap Size inches 1/2 3/ /4 1 1/ / / NOTE: Pipe thickness required for different tap sizes as per ANSI/ASME (American Society of Mechanical Engineers, 345 E. 47th St., New York, NY 10017) B for standard taper pipe threads with two, three and four full threads. To convert inches to millimeters, multiply by BRO-035

4 P 4 Pipe Thickness Required for Different Tap Sizes (cont.) Pipe Size inches No. of Threads Tap Size inches 1/2 3/ /4 1 1/ / / NOTE: Pipe thickness required for different tap sizes as per ANSI/ASME (American Society of Mechanical Engineers, 345 E. 47th St., New York, NY 10017) B for standard taper pipe threads with two, three and four full threads. To convert inches to millimeters, multiply by BRO-035

5 P 5 Tapping Test Details Tests performed by the Ductile Iron Pipe Research Association prove that.25" wall Ductile Iron pipe can be tapped with 3/4" or 1" service taps without using tapping saddles. Tapping tests that were performed and the results of these tests are outlined below. Test Details Pipe Specimens: Two test specimens of nominal 6" diameter Ductile Iron pipe, each 4 feet in length, were cut from a full length piece of pipe (18 feet). Average wall thickness of the pipe was 0.257". The pipe was cement-mortar-lined with an average thickness for the lining of 0.164". Each 4' length was capped at both ends and installed in a test press. Provisions in the end caps permitted filling the pipe specimen with water, release of entrapped air and connections to a high pressure pump and pressure gauge for subsequent pressurization to desired levels. Corporations & Tapping Six 3/4" corporation stops were installed in one pipe specimen while six 1" corporation stops were installed in the other 4' pipe specimen. The corporation stops were Mueller #H-9971 and all were new. A Mueller B-100 tapping machine was used to install the corporations in accordance with the recommended procedure. Mueller # and # combination drills and taps were used in the tapping machine to drill and thread the holes for installation of the corporations. Both combination drills and taps were new. Special Corporations Two each 3/4" and 1" corporations (all new) Mueller #H15050 were obtained for installation in the pipe specimens as substitution for some of the #H-9971 corporations. The #H15050 corporation has a compression ring or collar and a compression nut which was tightened following the usual installation of the corporation in the tapped hole. The compression of the ring or collar by the nut is designed to prevent leakage at the threads of the corporation inlet and the pipe wall. Corporation Selection Thread Engagement Water utilities frequently install 3/4" and 1" corporations in nominal 6" diameter pipe. It is usual for the utilities to standardize on one size, such as 5/8", 3/4" or 1" for 6" pipe to reduce inventory or to avoid confusion. The test used 3/4" and 1" corporations since a difference in the number of threads per inch on the inlets occurs between these two sizes of corporations. The 3/4" corporation has 14 threads per inch while the 1" has 12 threads per inch. Corporations smaller than 3/4" also have 14 threads per inch while those larger than 1" (1-1/4", 1-1/2" and 2") have 11-1/2 threads per inch. Thread engagement for 3/4" corporations (14 t.p.i.) in a 0.257" pipe wall is equivalent to approximately 3.6 threads. Thread engagement for 1" corporation (12 t.p.i.) in the same pipe is equivalent to approximately 3.08 threads. The number of full threads engaged increases as pipe diameter increases. BRO-035

6 P 6 Test Procedure The corporations were installed using the equipment described with six 3/4" corporations being installed on one pipe specimen and six 1" corporations installed on the other. No thread lubricant or sealant was used on any of the corporations in the initial tests as this duplicates the practice frequently used in the field. The corporations were installed and tightened with a torque wrench to an initial 50 ft/lbs. Additional torquing to stop leakage at the inlet threads was made in the same manner and recorded. The six corporations installed in each of the two test specimens were placed in two rows, three to a row, with approximately 60 degrees between the rows. The corporations were separated longitudinally by approximately 10 inches. The two rows were offset longitudinally by about 3 inches to facilitate attachment of the tapping machine. After filling the test specimen with water and bleeding off entrapped air, the test pressure was increased in steps and held at each stop to permit close inspection of the corporations and the test pipe and/or the tightening of corporations to stop leakage if noted. Following the test run where no thread lubricant or sealant was used, the corporations were removed and reinstalled in the same holes after the threads received a double wrap of Teflon tape to act as a thread lubricant and sealant. The same step-by-step test procedure was repeated. The Teflon tape was used since it is non-toxic and does not contribute to taste and odor problems in the water. Other lubricants or sealants can be used but toxicity and possible contribution to taste and odor in the water would have to be determined. One of each size of the #H corporations were substituted for one of the #H-9971 corporations following the test series using the Teflon tape. The #H corporations, however, were installed without the use of the Teflon thread tape. The preceding tests were duplicated for both the 3/4" and 1" corporations. Copies of test details are available upon request. The final test involved pressurizing the specimen with 1" corporations, including the #H-15050, to 1,000 psi to determine if the corporations might blow out of the pipe or the pipe wall deform in the vicinity of the corporations. Leakage, as reported in the test results, was that amount of water escaping which exceeded one drop per minute. BRO-035

7 P 7 Observations and Comments 1. Under the conditions of the tests, leakage occurred at the inlet threads (pipe wall) of the corporation fittings in 50% of the total 3/4" corporations installed without thread lubricant or sealant at 45 psi and 50 ft.-lbs of torque. Five of the six 3/4" corporations were torqued at different pressure levels to 90 ft.-lbs to stop leakage. 2. Under the same test conditions, leakage occurred at the inlet threads (pipe wall) of the 1" corporation fittings in five of the six installed at 45 psi and 50 ft.-lbs of torque. These corporations were installed without thread lubricant or sealant. Five of the six 1" corporations were torqued to 100 to 130 ft.-lbs at different pressure levels to stop leakage. 3. The use of the inert Teflon tape as a thread lubricant and sealant prevented all leakage at the inlet threads in both sizes of corporation fittings at all test pressures with only 30 ft.-lbs of torque when initially installed. 4. Mueller #H corporations, sizes 3/4" and 1", were used. The #H corporation has a compression ring or collar and compression nut which is tightened following the usual installation of the corporation in the tapped hole. The compression of the ring or collar by the nut prevented leakage at the inlet threads through all test pressure levels. Conclusion In view of the excellent results obtained from applying Teflon tape to the male threads of the corporation stops, it is recommended that this procedure be adopted as standard practice and it is further recommended that Ductile Iron pipe with a.25" wall be tapped with a 3/4" or 1" service taps without tapping saddles. NOTE: Copy of test details available upon request. BRO-035

8 P 8 Products for Water, Wastewater and Fire Protection Ductile Iron Pipe SIZE RANGE TYTON JOINT Pipe Mechanical Joint Pipe 4"-12" Ductile Iron TR FLEX Pipe HP LOK Restrained Joint 30"-42" Flanged Pipe 3"-64" Ductile Iron USIFLEX Boltless Flexible Joint Pipe 4"-48" Ductile Iron for Subaqueous Installations Restrained Joints TR FLEX Pipe HP LOK Restrained Joint 30"-42" MJ FIELD LOK Gaskets 4"-24" FIELD LOK 350 Gaskets 4"-24" FIELD LOK Gasket 30" & 36" TR FLEX GRIPPER Rings 4"-36" Ductile Iron TR TELE FLEX Assemblies 4"-24" Ductile Iron Ductile Iron Fittings TYTON Fittings TRIM TYTON Fittings TR FLEX Fittings and TR FLEX Telescoping Sleeves Mechanical Joint Fittings TRIM TYTE MJ Fittings Flanged Fittings XTRA FLEX Couplings 1 4"-12" Ductile Iron 3"-48" Ductile Iron 3"-48" Ductile Iron 3"-64" Ductile Iron 4"-24" Ductile Iron Miscellaneous Products PROTECTO 401 Lined Ductile Iron Pipe for Domestic Sewage and Industrial Wastes FLANGE-TYTE Gaskets 4"-64" Saddle Outlets Various Ductile Iron Welded Outlets Various Ductile Iron Polyethylene Encasement 4"-64" Our products are manufactured in conformance with National Standards so that our customers may be assured of getting the performance and longevity they expect. Use of accessories or other appurtenances that do not comply with recognized standards may jeopardize the performance and longevity of the project. BRO-035

9 All U.S. Pipe brochures and/or products are subject to change without further notice. P.O. BOX BIRMINGHAM, AL DIP.PIPE ( ) FAX: