TPT May 2016

AR T I C L E

SMS Group

Machinery and plants for the production of oilfield tubulars By Dr Ing Hansjörg Hoppe and Dr Ing Hans Pelster, SMS Group

produced on SMS group cold pilger mills. The SMS group also offers complete hot and cold processing lines as a package solution. These include, in addition to the core machines such as extrusion press lines or cold pilger mills, machines for billet preparation, pickling and degreasing facilities, finishing and testing equipment – in some cases from subcontractors. Production of high-alloy oilfield tubulars Stainless steels or nickel-based alloys are melted in an electric arc furnace melting process or in induction furnaces under the exclusion of air, and are further processed in downline plants by argon-oxygen decarburisation (AOD) or vacuum-oxygen decarburisation (VOD). If the batch size allows, continuous cast starting material is used; otherwise chilled cast material is used. Simple austenitic steels can be extruded directly without prior hot forming. Higher alloy materials must first be forged or hot- rolled in order to break down the linear casting structure and achieve a homogeneous microstructure. The product portfolio of the SMS group includes all the plants for primary and secondary metallurgy for the melting of high- purity stainless steels and nickel-based alloys as well as the necessary casting plants. After casting, the round ingots are rolled to the required billet size or forged on radial forging machines from the SMS group. In the final work step, the rolled or forged bars have to be peeled in order to create the surface quality necessary for the extrusion process. Peeling is performed on special machines from the SMS group.

xx The rising worldwide demand for oil and gas is leading to ever deeper well depths. Well depths of 25,000ft (7,620m) and more are no longer unusual. Generally speaking, increasing depths mean increasing temperatures and pressures. Many high-pressure and high-temperature (HPHT) wells with temperatures up to 400°F (204°C) and pressures up to 20,000psi (138MPa) have already been drilled. At the bottom of the well, the conditions become even tougher. The real challenges for the materials from which the oilfield tubulars are produced arise during the oil and gas extraction. Depending on the temperature, pressure, flow velocity and corrosive constituents in the gas stream, such as H 2 S and CO 2 , the use of low-alloy steel, high- alloy stainless steel, nickel-based alloys or titanium alloys is necessary. The use of oilfield tubulars made from high-alloy materials is always necessary when one of the following concentrations is exceeded in the oil or gas stream: • pCO 2 concentration > 1,500psi • Cl- concentration > 250mg/l • pH 2 S concentration > 10psi • Temperature > 390°F Commonly used high-alloy and corrosion-resistant materials are duplex steels (22Cr-5Ni), super-duplex steels (25Cr-7Ni-N), super-austenitic steels such as alloy 28 (28Cr-32Ni), nickel- based alloys such as alloy 825 (42Cr-21Cr-3Mo) or titanium alloys such as Ti Grade 5 (Ti-6Al-4V). The material to be chosen for a particular application depends on the corrosion conditions. Currently most manufacturers are limited in the production of large-diameter, high-alloy oilfield tubulars that have to be cold worked in order to achieve the strengths necessary for such deep wells. There is a growing demand for tubings and casings up to outside diameters of 10 3 / 4 " (273.1mm) and appropriate lengths from 30 to 40ft (9 to 12m). The SMS group as a system supplier offers its customers tailor-made solutions. Hot-finished, high-alloy oilfield tubulars or mother tubes that still have to be cold-formed can be produced in the diameter range 33.4 to 323.9mm (nominal 1 to 12") on extrusion press lines from the SMS group. Cold- rolled tubes in the diameter range from 5 to 280mm can be

Figure 1: Layout of extrusion press line

1 Rotary gas furnace 2 Induction furnaces 3 Glass lubrication 4 Piercing press 5 Hydraulic station

6 Final heating 7 Glass lubrication 8 Extrusion press 9 Water quenching 10 Cooling table

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M AY 2016