Pipe fittings in duplex stainless steel with deviation in quality caused by sigma phase precipitation

Børvik, Tore; Lange, Hans I.; Marken, Lene Anita; Langseth, Magnus; Hopperstad, Odd Sture; Aursand, M.; Rørvik, Gisle

doi:10.1016/j.msea.2010.06.087

Cited by 21 publications

(21 citation statements)

References 22 publications

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“…The procedure for the manual point count is described in more detail in Børvik et al (2010), while both estimated and counted sigma phase levels are given in Table 2. The agreement between the assumed and measured sigma phase levels was judged to be acceptable.…”

Section: Astm E662 "Standard Test Methods For Determining Volume Fractmentioning

confidence: 99%

“…Measured Cauchy stress versus logarithmic strain curves to failure are shown in Fig. 2 for the duplex stainless steel with different levels of sigma phase (Børvik et al 2010). The influence of the hard and brittle sigma phase into the originally ductile material is a slightly higher tensile stress level and a marked reduction in the strain to failure.…”

Section: Materials and Test Samplesmentioning

confidence: 99%

“…A thermal conductivity measuring cell operates as a hydrogen detector, and the hydrogen content is registered. The details in the procedure are described in Børvik et al (2010), while the results from the measurements are given in Table 2. The total hydrogen content in the sigma-free fittings were found to be about 4 times higher than in the fittings with 8 vol.% sigma, even though the procedure for hydrogen charging was identical.…”

Section: Measuring Of Hydrogen Contentmentioning

confidence: 99%

“…In a recent study by Børvik et al (2010), the mechanical properties of pipe fittings in duplex stainless steel (DSS) with deviation in quality caused by sigma phase precipitation were investigated. Such fittings are used both top-side and subsea in large amounts by the offshore industry, and may be exposed to accidental loads such as impacts from dropped objects while in service.…”

Section: Introductionmentioning

confidence: 99%

“…Approximately 20.000 fittings were produced before the mistake was discovered by chance. Fittings with deviation in quality were detected both in stock and in service by Statoil, and three typical levels of sigma phase In Børvik et al (2010), the effect of sigma phase on the mechanical behaviour of DSS pipe fittings was studied at the material level. This was done by conducting quasi-static and dynamic tensile tests at room ( 20 C  ) and low ( 46 C, 10 C     ) temperatures.…”

Section: Introductionmentioning

confidence: 99%

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Influence of sigma-phase precipitation on the impact behaviour of duplex stainless steel pipe fittings

Marken

Langseth

Rørvik

et al. 2014

Ships and Offshore Structures

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In this study, the effect of sigma phase precipitation in duplex stainless steel (grade 2205) pipe fittings collected from top-side process systems offshore was investigated under realistic loading conditions. This was done by conducting quasi-static and dynamic impact tests on 3" fittings with nominal outside diameter of 88.9 mm, nominal wall thickness of 3.05 mm and D/t-ratio of nearly 30. The fittings had a sigma phase level between 0 and 15 vol.%, and were loaded by a massive steel indenter with a hemispherical nose of 25 mm radius. In the quasi-static tests, the loading rate was 2 mm/min, while in the dynamic tests the impact velocity was varied between 5 and 10 m/s.A few dynamic impact tests on 2" fittings with an increased wall thickness and low sigma phase levels were carried out for comparison, while some 3" fittings were pre-charged with hydrogen before dynamic testing to examine the effect of sigma phase on cathodic protected subsea components. When the sigma phase level was low (i.e., 5 vol.%   ), no evidence of fracture was found in any of the pipe fittings, whereas at higher sigma phase levels

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Section: Astm E662 "Standard Test Methods For Determining Volume Fractmentioning

confidence: 99%

Section: Materials and Test Samplesmentioning

confidence: 99%

Section: Measuring Of Hydrogen Contentmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations