Proprietary technology: Super duplex stainless steels

Development and commercialization of pump casings using a type of super duplex stainless steel

Background to the development of super duplex stainless steels

Duplex stainless steels are superior in strength to conventional products, and, in particular, they have excellent pitting corrosion resistance, crevice corrosion resistance, and stress corrosion cracking resistance in environments exposed to chlorides. They have long been used for chemical plants, marine equipment, and other purposes involving corrosive substances; however, since in recent years stainless steel has been used in extremely harsh corrosive environments, the demand for duplex stainless steels of even higher performance has increased. In response to such demand, super duplex stainless steels with improved pitting corrosion resistance and strength were developed. In addition to having very strong durability and pitting corrosion resistance, super duplex stainless steels (which have lower nickel content than austenitic stainless steels) are highly cost effective.

Production of pump casings made of a type of super duplex stainless steel

Due to soaring crude oil prices in recent years, it has become necessary to redevelop low-grade oil fields and gas fields, development of which had previously been difficult. This required high pressure pumps; however, conventional products made by casting had limitations in terms of strength. Oilrig components, which were previously made using castings, now had to be made using steel forgings, which are superior in strength. Super duplex stainless steels, containing a high level of nitrogen, are difficult to hot-work. They are also susceptible to sigma phase precipitation during processing, and therefore were difficult to forge. Based on many years of accumulated experience, we at Pacific Steel Mfg., attempted to make thick-walled pump casings by forging, and succeeded in making a product compliant with the ASTM-F55 specification as a result of much trial and error.

Integrated production to respond to specific needs

As Pacific Steel Mfg. handles the entire process from melting and refining to machining, it is possible to make improvements based on customer requests. We have conducted research on optimal composition and forging methods for various purposes. Our mission is to exceed our customers’ needs and expectations, leveraging the technology and experience accumulated over 75 years since our foundation, through experiments, simulations, and other approaches using the latest equipment.