Introduction about Pipeline Hot Tapping

What is Hot Tapping ?

Hot Tapping is the drilling under pressure, in other words, more specifically, hot tapping mean that a pipe or other pressure vessel is drilled through, while the system remains in service (under pressure) .

There are many reasons to do this, and by the same token, there are many good reasons to not do this, if a system can be shut down, in order to perform the drilling operation.  A good example of a need to perform a hot tap, is to connect a service (for example a new homeowner needs water service connected to a system serving many others).  Other people would be inconvenienced if the system were to be shut down, depressurized, connected, sanitized?, brought back online, all to connect one service.  For this reason, it is very common to perform a hot tap.  (A hot tap is commonly assumed to mean drilling into a pipe that is live, it may, or may not actually be “hot”).


Why we want to do Hot Tapping ?

It is really a lot of trouble to perform a hot tap, but these operations provide us a tool to be used, to avoid shutting down a pipe system. In order to shut down a pipe system, it may be necessary to depressurize, purge, clean, inert etc.  To bring the system back up, may take just as much work.  For example, in an industrial process unit, shutting the unit down might take days, or longer, result in hundreds of thousands of dollars in lost production, and would impact other operations in the facility.  For this reason, continuous operating systems, such as chemical process units, refineries, power plants, etc., shut down very rarely, for them, a hot tap, or line stop, is the only economical option.  By the same token, if a city water system is shut down, as it loses pressure, contaminants could enter the system from groundwater, therefore, municipal water systems are also on and pressurized 24/7.  In all of these cases, it is very desirable to remain in service, under pressure, and operating. 

Please note, Hot tapping is science, and art, the state of the industry is such, that there are as many unanswered questions, and items to still be determined, as there are hard fast answers.  For example, at 1 ft/second, flow velocity, the coupon (section of pipe that is cut out), will generally not be pulled off of the pilot bit, with u-wires, to retain it.  On the other hand, at 1000 ft/second, nothing that is currently available in the industry, would keep the coupon (or pilot bit for that matter), in place.  For this reason, often the client will ask, is this flowrate too high, or can I go higher.  There are also higher pressures, larger sizes, and many other areas to be developed in the art, sizes greater than 48” diameter for line stops, and 72” diameter for hot taps, become very rare,


Hot tapping involve the use of specialized equipment and highly trained technicians, in order to cut a hole in a pipe, without taking the pipe out of service, or lowering the pressure.  This is most often done in Chemical Plants, Refineries, Power Plants, Manufacturing Plants, Nuclear Power Plants, or any other location, where loss of service, is not acceptable.  This paper is intended to be a primer of the hot tap and line stop operation, primarily intended for those who have little if any prior knowledge of the process. This work is highly technical, requires years of training, highly specialized equipment, and should not be attempted without proper training and instruction. 

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