Yes, Ductile Iron products can be successfully Glass lined. Glass lined pipe and fittings have been specified and utilized as a deterrent to interior build-up and clogging of problematic sludge and scum piping systems in wastewater and sewage treatment facilities for over 40 years. Not only is the excellent non-stick characteristic effective in combating the build-up of grease, sludge, and scum, but has been found to be the only deterrent to Struvite and Vivionite build-up as well.

While other manufacturers are licensed to manufacture the TYTON JOINT® through 24" diameter, only TYTON JOINTS® conforming to current joint configurations which allow 5 degree joint deflection are applicable with FIELD LOK 350® gaskets.

U.S. Pipe does not recommend the use of a FIELD LOK® Gaskets with a TYTON® Plugs. Due to the fact that you cannot get the gasket out unless you cut the pipe bell off because of the flange on the end of the plug. If the plug is pushed in too deep then the set screw holes can be in the gasket bulb causing it to leak. Since the installation was performed with a FIELD LOK Gasket, you cannot pull it out and the fitting or pipe bell would have to be scrapped.

Yes, you can. Ductile Iron pipe and fittings can be direct tapped for air release valves, sampling ports, service connections, etc. You do want to ensure that there is adequate thread engagement to provide both strength and a leak-free seal. Testing has shown that, with the use of a good thread sealant, as little as one full thread engagement will provide a leak-free tap. Following the conservative nature of our industry, we recommend that you choose at least two full threads of engagement.

The limiting factor in achieving adequate thread engagement for a given metal thickness is the relative curvature of the parent body as the size of the tap increases. There are tables in AWWA/ANSI C151/A21.51 which show the maximum size of tap that can be used on a given size of pipe, and thickness to achieve 2, 3, or 4 thread engagement.

Also, you can order fittings with a boss cast at the location of the desired tap. The flat surface of the boss, along with the increased metal thickness, provides for multiple thread engagement of tap sizes larger than could be accommodated on the curved surface of the fitting.

Yes. The TR FLEX® joint is easily disassembled by following the assembly instruction found in our TR FLEX® Pipe and Fittings brochure. The FIELD LOK 350® gasket requires a disassembly kit that can be purchased through your U.S. Pipe Representative.

FIELD LOK 350® gaskets cannot be used for bridge crossings. The FIELD LOK 350® gasket is a friction restrained joint and due to the fact that bridges are subject to vibration from vehicles traveling over the bridge, there is a possibility that the gasket could work itself lose. U.S. Pipe's recommendation for bridge crossings is TR FLEX® pipe.

Appendix A of ANSI/AWWA C151/A21.51, Ductile Iron Pipe, Centrifugally Cast, for Water, contains the minimum metal wall thickness required for 2, 3, and 4 threads for different diameter threaded outlets and different diameter pipe. Information is given for both threads conforming to Standard ANSI/ASME B1.20.1 (a.k.a. National Pipe Thread (NPT), Iron Pipe Thread (IP), or Standard Taper Pipe Thread) and AWWA C800 (a.k.a. Mueller Thread, cc thread, Corp Stop Thread). To assure adequate metal thickness for a particular pipe diameter and Pressure or Thickness Class, it is necessary to subtract the casting tolerance found in the Table in Section 4.4.2 from the Nominal Metal Wall thickness found in Table 1 of ANSI/AWWA C151/A21.51.

Concerning the security of a two engaged threads engagement, the Ductile Iron Pipe Research Association (DIPRA) conducted a study of ¾-inch and 1-inch corporation stops direct tapped into 6" Pressure Class 350 pipe. The tests were conducted on pipe sections with less than nominal metal wall thickness. After multiple corporation stops were installed in each piece of pipe under city line pressure, the installations were observed for leakage through the threads.  The water pressure was then raised to 1,000 psi in an effort to fail the 6" pipe and threaded connection. Leakage was not observed at the threaded connection. These tests were conducted with and without 3-mil thread sealing tape applied to the threads of the corporation stop. The installed corporation stops were then subjected to pull-out and cantilever load tests.  In the pull-out tests, the corporation stop failed at loads in excess of 6,500 pounds of force. The pipe threads were undamaged in each of the three tests. In the cantilever load tests, the corporation stops failed at bending moments in excess of 385 foot-pounds of force. Again the threads in the ductile iron pipe wall were undamaged. 

It can be clearly seen that work crews can direct tap service connections into Pressure Class Ductile Iron pipe under pressure, effecting structurally secure, watertight seals. It is recommended that two layers of 3-mil thread sealant tape be applied to the corporation stop threads to achieve a watertight service connection using a minimal tightening torque.

The results of this study have been published by the Ductile Iron Pipe Research Association under the title Direct Tapping of 6-inch Pressure Class 350 Ductile Iron Pipe and is available through the Web Site http://www.dipra.org.

Yes. PROTECTO 401™ Joint Compound is the material approved for patching the ends of field cut pipe or for repairing any damage detected prior to installation. A touch-up kit is available for contractors and fabricators.

Because buried Ductile Iron pipelines are electrically discontinuous and are essentially grounded for their entire length, overhead AC power lines normally don't impose corrosion or safety concerns.

A consequence of AC power lines and buried pipelines sharing rights-of-way is that AC voltages and currents can be induced by magnetic induction on the pipelines. The magnitude of the induced voltage and current on the pipeline is a function of a number of variables, including the length of pipeline paralleling the AC power line, the longitudinal resistance of the pipeline, and the resistance of the pipeline coating.

Ductile Iron pipe is manufactured in nominal 18- and 20-foot lengths and employs a rubber-gasketed jointing system. These rubber-gasketed joints offer electrical resistance that may vary from a fraction of an ohm to several ohms, but nevertheless is sufficient for Ductile Iron pipelines to be considered electrically discontinuous. In effect, the rubber-gasketed joints segment the pipe and prevent magnetic induction from being a problem. Also, in most cases, Ductile Iron pipelines are installed bare and are therefore essentially grounded for their entire length, which further prevents magnetic induction on the pipeline.

During construction of Ductile Iron pipelines in the vicinity of overhead AC power lines, certain safety precautions should be followed, e.g., "limit of approach" regulations governing construction equipment, grounding straps, or chains attached to rubber tired vehicles to provide a ground, etc.

External
The corrosion rate of Ductile Iron in sea water will normally vary between 2 and 20 mils per year depending on such factors as: whether the pipe is buried beneath the ocean floor, whether the sea water is continuously flowing or moving, depth beneath the surface (which influences oxygen concentration), whether the pipe is continuously submerged or at tidal levels, and a number of other factors. Polyethylene encasement has been used for pipe buried beneath the ocean floor. For applications where the 2 to 20 mil corrosion rate is unacceptable, or where polyethylene encasement cannot be used, contact your U.S. Pipe Sales Representative for specific recommendations.

Internal
As stated above, the corrosion rate of Ductile Iron in sea water is relatively low (between approximately 2 and 20 mils per year depending upon operating conditions). For extra protection in sea water, a 4 to 10 mil thick coating of epoxy is normally recommended for exposed iron in the joints (i.e., on the extreme spigot end of the pipe and in portions of the bell). Type V sulfate resistant cement, double thickness, in accordance with AWWA C104 Standard is also recommended for this type of service.