Mechanized Welding Systems for Gas and Water Pipelines
Welding cross country oil and gas pipelines along with water pipelines is one of the most demanding tasks in mechanized welding. Magnatech's welding systems are in daily use in desert conditions in Saudi Arabia, where blowing winds are a constant and temperatures reach 120˚F (49˚C) and higher. They are also used in harsh winter conditions in Canada, where temperatures drop to -40˚F (-40˚C). Because only one pipe length can be added at a time to the existing line, equipment reliability is paramount in joints-per-day productivity.
Magnatech offers welder training anywhere in the world, assistance in developing weld procedures, and long term support when required. Magnatech has a proven track record of successful pipeline welding projects.
Pipeline welding calls for the very best mechanized welding systems and support, and Magnatech is up to the task.
Oman has significant quantities of "sour" oil and gas, containing dangerous and corrosive hydrogen sulfide (H2S) and carbon dioxide (CO2). It is necessary to use carbon pipe lined with a corrosion resistant alloy (CRA) to withstand the rapid corrosion that would occur to unprotected pipe.
The root pass must smoothly join the CRA cladding without dilution by the base carbon pipe material. The GTAW process is specified; slower but producing consistent welds to the highest quality standards. The main contractor, Petrofac, worked with Tekfen Construction and Installation.
Welding was done using 13 Magnatech T-Head/Pipemaster systems. Factors contributing to this decision included lack of skilled labor, high weld quality requirements, and the project timetable. Tekfen used portable metal huts as a wind barrier for the field welding, with two systems mounted in each hut.
Completed welds underwent Visual Examination (outside and inside) and both radiographic and ultrasonic Testing to API 1104.
"Although Tekfen has significant experience in cross country pipeline projects in the Middle East, the Harweel project being the first on-shore CRA-clad construction in the world was a challenge for all disciplines and parties. Magnatech, along with their knowledge and technical personnel, partnered with us in solving the problems that arose during the project, and contributed to the project success", states Cem Ozbay, Engineering Manager. The project was successfully completed in 2010.
A pipeline contractor, Raymond International, was awarded a contract to weld 10km (300,000 tons) of X-60 pipe with a 15mm wall thickness. The project consisted of welding mortar-lined water transmission pipelines from the power and desalinization plant at Hidd, Bahrain to multiple storage and pumping stations for transmission throughout Bahrain. Pipe sizes included 42", 45", and 72" diameter. Welding had to be done in a 7m deep pipeline trench which was below the water table, presenting a harsh environment.
Welders put the root bead in using semiautomatic wire feeders with solid wire. This process eliminates the need for a second hot pass (which would normally be required using manual SMAW) before the FCAW fill passes could be initiated. Two Pipeliner mechanized FCAW systems were used for fill and cap passes. The client's specification required 100% radiography of the welds if welding was to be done using manual SMAW. This was relaxed to 20% when it was decided that mechanized welding was to be utilized, providing substantial savings. The overall repair rate was less than 2% with a majority of indications in the semiautomatic root pass.
The Haradh Gas Program consists of 87 upstream gas wells and flow lines, a gathering manifold, processing facility and downstream pipeline networks. The Haradh manifold, 12 km from the processing facility, collects both sweet gas in 30" lines and sour gas through two 24" lines. Pipe material is API 5L X65. Saudi Aramco raised their quality standards and specified that the procedures be qualified not only to the pipeline industry standard API 1104, but also the more demanding ASME B31.3. This required the use of new equipment and techniques to achieve the mandated quality and meet project deadlines.
The contractor utilized 20 Pipeliner systems, which use the Flux Core Arc Welding (FCAW) process. This forgiving process allows operation by lower-skilled welders. The project defect rate was zero percent, and contributed to the early completion of the manifold project in 31 versus the scheduled 37 months.
An energy company, Dong A/S, required a number of pipelines to transport natural gas from producing fields in the North Sea to the European gas infrastructure. A construction contract was awarded to Aarsleff-Freytag JV, who decided to evaluate mechanized pipeline welding for the 1800 welds required to be made.
Ole Munch Andersen, Project Manager, states "Joint Venture Aarsleff-Freytag J/V had the construction contract of the on-shore part of the South Arne-Nybro pipeline in Denmark.
The project comprised of construction 18.7 km, 24", 15.1 wt pipeline in the southern part of Jutland, Denmark. The pipe class was X65.
For the welding of the pipeline the Joint Venture used manual cellulose stick welding for root and hot passes. The fill and cap passes were done using the Magnatech welding system. This welding system was used for mainline welding, [using] a standard 30 degree bevel.
The project was satisfactory completed on time with an acceptable fault rate, and the quality of the welds were high. The welding method and welding system proved to be reliable for the job and can be recommended for other jobs of similar character."
Saudi Aramco built a major gas plant to process 4 billion standard cubic feet per day (scfd) of gas to 310,000 barrels of ethane and natural gas liquids (NGL). Suedrohrbau Saudi Arabia Ltd was selected as the pipeline contractor.
Mr. Riad Bazzi, Projects Director: "We are pleased to state that we are using Magnatech Pipeliner II Systems on our new Saudi Aramco […] Hawiyah NGL Recovery Plant Upstream & Downstream Gas Pipelines for construction of 48" and 56" pipelines, and using the Magnatech Pipeliner II Systems we were able to achieve a very high quality of welding
Pipeline descriptions and number of joints involved are as follows:
48" X 0.605" & 0.871" wall thickness = 53 km length
No. of joints welded = 1145 joints
56" X 0.649" & 0.893" wall thickness = 10.4 km length
No. of joints welded = 188 joints
The cumulative weld repair rate on linear basis was 0.011%.
We take this opportunity to place on record our appreciation of the efficacy and efficiency of the Magnatech Pipeliner II Systems and, going by our experience, would not hesitate to recommend them to other construction contractors with pipeline projects in hand."
A Bolivian power company required 5 kilometers (3.1 miles) of penstock to be fabricated in the field as part of a hydroelectric power facility. Short sections of 1.2 to 2.4 meters (47 to 94 inches) diameter had to be welded on slopes with a 35-degree inclination. A pressure balancing surge tank, consisting of a vertical pipe 150 meters (492 feet high) and 1.6 meters (63 inches) in diameter also required welding on site.
The company awarded the contract to Carlos Caballeros, who used a T-Head Model 419 (GTAW) for root pass welding and an MPS 4000 Pipeliner System unit (FCAW) for fill passes. Welds had to be done both on the outer and inside diameters. Fix-Track was used with magnet attachments.