Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Seawater duplex steels

Materials such as metals, alloys, steels and plastics form the theme of the fourth chapter. The behavior and use of cast irons, low alloy carbon steels and their application in atmospheric corrosion, fresh waters, seawater and soils are presented. This is followed by a discussion of stainless steels, martensitic steels and duplex steels and their behavior in various media. Aluminum and its alloys and their corrosion behavior in acids, fresh water, seawater, outdoor atmospheres and soils, copper and its alloys and their corrosion resistance in various media, nickel and its alloys and their corrosion behavior in various industrial environments, titanium and its alloys and their performance in various chemical environments, cobalt alloys and their applications, corrosion behavior of lead and its alloys, magnesium and its alloys together with their corrosion behavior, zinc and its alloys, along with their corrosion behavior, zirconium, its alloys and their corrosion behavior, tin and tin plate with their applications in atmospheric corrosion are discussed. The final part of the chapter concerns refractories and ceramics and polymeric materials and their application in various corrosive media. [Pg.582]

In recent deeades, also relatively high alloy ferritic-austenitic steels (duplex steels) have been developed. Earlier, these steels were considered immune to chloride SCC. However, both laboratory experiments and experience of fracture on installations in the North Sea have shown that SCC can occur on duplex steels under unfavourable eonditions developed beneath the thermal insulation on hot steel surfaces. The insulation is used to reduce heat loss and to protect people. If seawater penetrates the insulation and reaches the steel surface, the water will evaporate and this causes chloride enrichment. Maximum unfavourable conditions can be established high chloride content, efficient oxygen access (there is a thin water film at the most critical sites), and temperatures above 100°C. Ferritic-austenitic stainless steels should not be used under these conditions. [Pg.167]

The use of stainless steel in oil production has increased, and is of particular significance for production in deep waters. This applies both to production and process equipment carrying oil and gas and to seawater systems. For seawater systems the experience from nuclear power plants has been useful. In these plants, some high-alloy steels have performed well in equipments such as seawater pumps and heat exchangers. But the performance depends on service conditions, design and combination of materials. On the oil/gas side, good experience has been obtained with 13% Cr steel in production tubing, in components at the wellhead and in well valves. The same can be said about the use of other stainless steels in process systems offshore, but there have been some exceptions. For instance, SCC has occurred on duplex steel (22-5-3) under external heat insulation (compare Section 7.12) [10.11]. [Pg.249]

For applications in seawater, the main steels used are X2CrNiMoN22-5-3 (2205, 1.4462), X3CrNiMoN27-5-2 (SAE 329, 1.4460) and the cast material GX8CrNiN26-7 (1.4347) [23]. The chemical compositions and the mechanical properties of these steels are in DIN EN 10088-1 to -3 [101,127] and, for the cast material, in SEW 410 [128]. The content of alloying elements is formulated in duplex steels so that the two structural components - the ferrite and austenite phases, are present in the struc-... [Pg.235]

The ferritic-austenitic steels are passive in seawater due to their high chromium content and do not suffer from general corrosion. Their resistance to pitting and crevice corrosion is raised by the molybdenum and nitrogen components. The duplex steels have therefore proved their worth well in a wide range of marine engineering apphcations [131-134]. [Pg.236]

Wallen, B. (1997), Corrosion of duplex stainless steels in seawater. Duplex Stainless Steels 5th World Conference, Maastricht, The Netherlands, 21-23 October 1997, 59-71. [Pg.621]

Appendix A contains a materials selection guide for aerated freshwater systems. As indicated in Note 27 of Appendix A, in freshwater systems, admiralty brass should be limited to a maximum pH value of 7.2 from ammonia and copper-nickel alloys and should not be used in waters containing more sulfides than 0.007 mg/L The materials selection guide is also satisfactory for seawater, although pump cases and impellers should be a suitable duplex stainless steel or nickel-aluminum-bronze (properly heat treated). Neoprene-lined water boxes should be considered. For piping, fiber-reinforced plastic (up to 150 psi [1,035 kPa] operating pressure) and neoprene-lined steel should also be considered. Titanium and high-molybdenum SS tubes should be considered where low maintenance is required or the cost can be justified by life expectancy. [Pg.19]

Selection of material. As dealt with in previous sections, conventional stainless steels, with martensitic, ferritic, austenitic or ferritic-austenitic (duplex) structure, are sensitive to crevice corrosion (Table 7.4). Newer high-alloy steels with high Mo content show by far better crevice corrosion properties in seawater and other Cl-containing environments (see Section 10.1). [Pg.121]

Type 304 and 316 stainless steel are used in the high-pressure pipes and pipe fittings in RO plants. The 300 series SS are also sensitive to chlorides at a pH of 6.5—8 and at temperatures below 60°C. Type 316 SS tolerates chlorides up to 1000 ppm, but concentrations can reach 26,000 ppm in dry zones (for MgCl2), resulting in failure. In seawater RO desahnation plants, duplex (2205) or super-duplex (2507) steels are used instead of 316 SS. The compositions of these steels are detailed below [25] ... [Pg.401]

S] Gardand, P. O., Steinsmo, U., Dmgli, J. M., and Solheim, P., High, Alloyed Stainless Steels for Chlorinated Seawater Applications A Summary of Test Results for Eleven Austenitic and Duplex Materials, Paper 646 NACE CORROSION/93, NACE Nashville, TN, 1993. [Pg.232]

Philips, L. M. Oldfield, J. W. Electrochemical tests to assess resistance to crevice corrosion in seawater of some duplex stainless steels... [Pg.282]

The effect of sigma phase precipitation at 800 °C on the corrosion resistance in seawater of a high-alloyed duplex stainless steel... [Pg.283]

The metallurgy selected for construction of a firewater pump is dependent on the properties of the water to be used. For fireshwater sources (i.e., public water mains), cast iron has normally been adequate, although bronze internals may be optional. Brackish or seawater utilization will require the use of highly corrosive resistant materials and possibly coatings. Typically specified metals include ally bronze, monel, ni-resistant, or duplex stainless steels sometimes combined with a corrosion resistant paint or specialized coating. [Pg.322]

Chlorides in the water can cause corrosion, particularly in the case of stainless steels. Typically 304 is satisfactory up to about 200 ppm chlorides, while 316 can withstand around 1000 ppm and 4.5 percent molybdenum austenitic stainless steels and duplex stainless steels are known to have suffered from crevice attack at 2000 to 3000 ppm beneath fouling. Titanium and the six percent molybdenum stainless steels have been shown to resist crevice attack in seawater (1900 ppm chlorides) under deposits. [Pg.294]

Almost all types of engineering materials have been reported to experience MIC by SRB copper, nickel, zinc, aluminium, titanium and their alloys [96, 97, 98], mild steel [72, 99, 100], and stainless steels [68, 80, 101, 28] are just some examples. Among duplex stainless steels, SAF 2205 has been reported for its vulnerability to MIC [44, 102, 103]. According to these studies, SAF 2205 can corrode and have pitting initiated due to the presence of SRB after immersion in seawater for more than one year (18 months) [102]. Corrosion rates of lOmm/year [5] in oil treatment plants and 0.7 mm/year to 7.4mm ear due to the action of SRB and/or acid-producing bacteria in soil environments [8] have been reported. [Pg.54]

Besides the reports of MIC described above that are mainly related to water with relatively low salt content such as fresh water, an increase in the corrosion potential has also been reported for stainless steels exposed to natural seawater. The ennoblement of the corrosion potential has been observed for various stainless steel compositions (i.e., austenitic, ferritic, duplex, and superaustenitic stainless steels) exposed in natural seawater with different salinities and at different temperatures Copyright 2002 Marcel Dekker, Inc. [Pg.586]

Piping for seawater duty should normahy be of 90/10 Cu/Ni conforming to the piping specification. High molybdenum austenitic and 25% Cr duplex stainless steels may offer cost and weight advantages over Cu/Ni, and should be evaluated for specific projects. [Pg.81]

Pumps handling seawater or brine above 40 °C contaminated with oil and HjS should be fabricated in one of the super duplex stainless steels or a more corrosion-resistant material. When a wet gas stream is corrosive, the first stage of wet gas compressors should be fabricated in a corrosion-resistant material such as 13% Cr steel. [Pg.82]


See other pages where Seawater duplex steels is mentioned: [Pg.557]    [Pg.1344]    [Pg.590]    [Pg.1377]    [Pg.229]    [Pg.244]    [Pg.416]    [Pg.316]    [Pg.290]    [Pg.291]    [Pg.341]    [Pg.519]    [Pg.138]    [Pg.514]    [Pg.760]    [Pg.64]   
See also in sourсe #XX -- [ Pg.15 ]




SEARCH



DUPLEX

Duplex steels

Duplexe

Duplexer

© 2024 chempedia.info