Substitution of Carbon Steels for ASME SA-533 Type E for Lightweight Equipment

International audienceThe use of MnMo(Ni) alloys ASME SA-533 type B or type C in lieu of carbon manganese steels (SA-516 Grade 65 or Grade 70) started about 30 years ago to produce lightweight pressure vessels. But the development of these low alloy steels for the fabrication of equipment for wet H2S service ("sour service") remains limited due to their weldability considered as challenging. This paper aims at introducing newly developed material ASME SA-533 type E class 2, and provides results obtained in base metal and welded joints, especially with respect to NACE standard MR0175 / ISO 15156-2. Finally, a case study on an absorber for amine gas treating units (AGRU) will be described to illustrate the mass savings that can be achieved with SA-533 type E class 2

Alternative metallurgies reduce the cost of amine gas treating units

International audienceProduction facilities, including platforms or FPSO, are becoming more and more complex structures. Reducing the weight of the process units is an important challenge, and represents a huge source of costs savings. IFPEN, PROSERNAT and INDUSTEEL have evaluated two alternative metallurgies with high mechanical properties to reduce the weight of equipment of amine gas treating units (AGRU). Duplex stainless steels are considered as an alternative to more conventional austenitic stainless steel grades. High strength alloy steel ASME SA-533 type E class 2, having an UTS above 90 ksi, can be an alternate to carbon steel ASME SA-516 Gr65 type (UTS 65 ksi). The compatibility of these steel grades with amine service was checked through autoclave corrosion tests in amine solutions. Various experiments were performed in conditions representative of the bottom part of absorber and of upper section of regenerator of AGRU, with variable loadings of CO 2 and H 2 S. Study used different specimens: weight-loss coupons, four-point-bend assemblies, and U-bends. For all these tests, alternative metallurgies proved to behave at least as well as the reference ones generally considered in amine plants with no significant corrosion nor cracking. In addition to experimental tests and presentation of steel properties, the paper describes a case study of AGRU where the mass gain and CAPEX benefits are elaborated for a 75 bar, 4.5 meters diameter absorber, and for a 4.8 meters diameter, low pressure, stripper