Weld Purging of Pipes for Oil and Gas Operations

Weld purging tubes and pipes for the oil and gas industry is crucial when joining metals such as stainless, duplex and chrome steels, as well as nickel alloys, titanium and zirconium. However, when welding larger pipe diameters it is not cost effective to completely fill tubes and pipes with expensive inert gas. Innovative QuickPurge® Systems from COB Industries, Inc. (Melbourne, FL) dramatically reduce the space that needs to be purged, thereby reducing purging time dramatically, making huge savings in both time and gas costs. Using QuickPurge means there is no longer a need to fill complete pipes with an inert gas. These systems are so efficient they pay for themselves in the first couple of welds in gas savings alone, whatever the pipe size. QuickPurge is simply inserted into a tube or pipe, inflated within the pipe, restricting the area that is to be welded, removing the oxygen down to 100 ppm (parts per million) within minutes.

For example, a 36 in diameter stainless steel pipe can be purged down to 100 ppm of oxygen in under 32 minutes. Compare this with weld purging using foam dams or other homemade devices that will outgas heavily into the welding zone and take many hours. Some features of QuickPurge include:

• An additional gas input line, allowing extra purge gas to be introduced for extra high speed purging down to the lowest oxygen levels, which is perfect for larger diameter pipes where quality welds are required. This extra cold argon gas input is perfect for mitigating the extra heat produced by the Plasma / TIG process.
• The advanced design of the QuickPurge System means that oxygen levels as low as 10 ppm can be reached every time, allowing zero color welds to be achieved with no loss of corrosion resistance caused by oxidation.
• IntaCal®, combined with the integrated PurgeGate® device, makes it possible to safely inflate the systems with argon gas, for sealing and then purging the space between the dams where the weld joint is located. With PurgeGate, any risk of over inflation is due to pressure or flow increase is eliminated.
• All systems are manufactured as standard with a hose for connecting a Weld Purge Monitor®, which can read oxygen levels down to as low as 1 ppm (accurate to 10 ppm).
• Materials used in the manufacture of QuickPurge are such that they are resistant to the higher weld temperatures present and they don’t outgas, thus preventing weld contamination.

For pre-heated chrome steel and high strength stainless steel pipe joints, HotPurge® Systems are available for a higher and longer temperature exposure. Effective plugging and sealing of pipes in heavy duty applications is essential, especially in refineries, offshore operations, plumbing operations as well as domestic and industrial water activities where the plug is likely to be immersed in chemicals or exposed to high temperatures. Heavy duty Aluminum Plugs from COB Industries allow for arduous duties, such as exposure to high temperatures and immersion in chemicals, in sizes 1.5 in to 36 in (38 mm to 900 mm). These plugs can be used to leak testing, isolation, sealing, stopping and weld purging of pipes. They are manufactured with a standard synthetic rubber seal, however, a variety of other sealing rings are available, including natural rubber, silicone, nitrile, neoprene and Viton to ensure they can be used for applications where greater resistance to a variety of materials is required.

Aluminum Plugs are available up to 36 in (900 mm), manufactured with a friction-free washer to ease tightening of the ring nut. All plugs conform to British Standards BS8005 and BS EN752-4 for low pressure testing and sealing of pipes. The Aluminum Plugs have a wide variety of other applications throughout sewage and drainage systems, ducting and conduit, swimming pools. They are also used to seal and protect tanks, vessels and containers during cleaning and transportation, particularly when they are pressurized with inert gas. Other plugs and stoppers include Mechanical Plugs for low, medium and high pressure stopping requirements, and Inflatable Stoppers that can be transported anywhere quickly and easily for a number of low pressure and medium pressure plugging and stopping applications.

In petrochemical and oil and gas operations, blocking pipes or other orifices to carry out routine maintenance and other applications can prove challenging where hydrocarbons are present in liquid and gas form. Hydrocarbon-resistant PetroChem® inflatable pipestoppers from COB Industries are manufactured by Huntingdon Fusion Techniques HFT® (Burry Port, Wales) in cylindrical and spherical formats from 1 in to 96 in (25 mm to 2,440 mm) diameter with a high grade latex, rubber internal inflatable bag covered with a petrochemical resistant layer that has a tough, woven impregnated nylon outer cover for use up to 90 deg C (194 deg F). These versatile inflatable stoppers are used to service a wide variety of industrial applications. As “overnight stoppers” they provide a strong barrier in pipeline activities to prevent foreign bodies entering the line during downtime. In machining applications, they can be inserted below a horizontal flange on a vertical pipe, to prevent machining fluid, swarf and tools from falling into expensive machinery, such as pumps and turbines etc.

PetroChem inflatable stoppers are particularly useful when one or more can be inserted into a small opening close to a work location, rather than at the end of the pipe, tank or vessel. No high pressure equipment is needed for inflation. These stoppers are available with optional heat-resistant covers to protect them against high temperatures of up to 300 deg C (572 deg F), ensuring the stopper is not damaged when exposed to high temperatures. The stoppers are light in weight, easy to manipulate, and can be shipped anywhere by next day courier at very low cost.

COB Industries, Inc., 6909 Vickie Circle, Melbourne, FL 32904, 321-723-3200, [email protected], cob-industries.com.