North American Oil & Gas Pipelines

OCT 2018

North American Oil & Gas Pipelines covers the news shaping the business of oil and gas pipeline construction and maintenance in North America, including pipeline installation methods, integrity management innovations and managerial strategies.

Issue link:

Contents of this Issue


Page 31 of 43

32 North American Oil & Gas Pipelines | OCTOBER 2 018 The Powermax125 can pierce 1-in. thick material and cut 1.5-in. thick materials at a speed of 18 inches per minute. The availability of several torch options gives the crew further versatility, to either cut by hand or use a machine torch like Wingo. This type of speed and versatility plays an impor- tant role in keeping pipeline work efficient. On the line, crews have found that using plasma cutting for tie-ins can be completed in 7.5 minutes. With oxy- fuel, the same job takes nearly 20 minutes longer — assuming everything goes smoothly, there are no de- lays in preheating, and the oxygen doesn't run out. Oxyfuel is a process that uses a fuel gas and oxygen to burn through metal. Though reliable, it has sev- eral drawbacks. One of the largest drawbacks is how slow it is. Part of the reason for the delay is the required pre- heating, which is when an operator has to heat up the pipe and burn back the coating before cutting. Another reason is the cutting process itself, which combines fuel, gas and oxygen. The oxygen is held in containers, which are heavy, pressurized and haz- ardous. As a result, only one or two containers can be transported at a time. When the oxygen inevitably runs out, welders must go back to the main staging yards for more. Pipeline crews must wait through both of these processes, and may end up stalled anywhere from thirty minutes to more than an hour. As one worker explained, "A pipeline is like an assembly line. One slowdown affects everyone on the line." With the help of plasma cutting, such stalls are becoming in- creasingly rare. Weld Repairs Pipeline contractors are also using the plasma to cut pipe to size and gouge out welds that need repair. Wingo says he used his Freedom units to cut pad eyes, making it a great investment. Before, three different processes — oxyfuel, air carbon arc gouging and grinding — were needed to do the same work. Weld repair is often considered the toughest job. When a weld doesn't pass inspection because of a defect found during radiographic or ultrasonic test- ing, a welder has to remove the old weld and re- place it with a new and stronger weld. During this process, there is a risk of burning a hole in the pipe. If this happens, the pipe is unusable and has to be replaced completely. Before, welders were using carbon arc gouging for repairs. An electric arc at the end of a carbon rod melts the metal, while a continuous blast of com- pressed air blows the excess metal away. Because of the brightness of the arc and the powerful nature of the air, which often pushed the metal towards a welder rather than away, workers had a difficult time seeing the pipe clearly. In addition to this, air carbon arc gouging can produce flames up to 15 ft away from the source — further, if it's windy. This endangered the pipeline's structural integrity and the safety of the crew. However, with the new plasma units, workers can carefully gouge out the old weld. Metal is pushed away more easily, less metal vaporizes, and there are fewer sparks. As a result, the welder has better visibil- ity and control. While the speed of the cuts is important, the quali- ty of those cuts is also essential to good pipework. The cuts have to be formed with just the right amount of bevel so a welder can come in and properly join the pipe to the line. The Powermax plasma found on the Freedom unit is created to do just that, ensuring accu- rate and smooth cuts that eliminate secondary work. It's easy to understand why pipeline and gas com- panies are increasingly embracing plasma for repair and rehab work. The safety features, ease of use, cut- ting speed, and cut quality in addition to a reduction of heat input by half, make plasma an exciting option for companies that not only value quality work, but the welfare of their employees too. Michelle Avila, is communications manager at Hyper t herm Inc . Plasma arc cutting oers an ecient and cost-eective alternative to oxy-acetylene cutting and carbon arc gouging. Pipeline and gas companies are increasingly embracing plasma for repair and rehabilitation work.

Articles in this issue

Archives of this issue

view archives of North American Oil & Gas Pipelines - OCT 2018