Monel is a nickel-copper alloy with high tensile strength and resistance to corrosion. The nickel content is as high as 67 percent. The balance of Monel is made up of iron, carbon, silicon and manganese. Monel is used to make pipes, valves and piping supports which are used in trenchless construction.
Trenchlesspedia Explains Monel
Monel is stronger than pure nickel and, because of the materials with which the nickel is alloyed, it readily resists the flow of saltwater, called scour. The alloy products in Monel also help prevent galvanic corrosion in a saltwater environment with the use of external sacrificial anodes.
Monel’s primary drawback is its cost when used for large-scale applications. In terms of its trenchless technology applications, Monel can cost more than three times what a pipeline made from steel costs which means its uses may be limited. Its chemically resistant properties make it a good choice for applications in the chemical and refining industries where it can withstand the corrosive environment of fluorides.
While Monel readily resists the effects of saltwater scour and saltwater product flows, it shouldn’t be used in saltwater applications adjacent to steel in saltwater applications. Galvanic corrosion will destroy Monel used next to or attached to steel unless zinc sacrificial anodes are attached to the Monel and replaced before half the anode dissolves.
One of the many uses of Monel in drilling is to ensure a drill string isn’t affected by the Earth’s magnetic field. Monel collars are used to isolate drill string instruments from the electromagnet pull of drill bits rotating as they bore a hole. If the tool is deflected by one or two degrees because of the natural magnetic field, the intended track of the bore can miss its intended target by several feet or yards, a potentially embarrassing and costly situation.