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 a 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. σ ⩽ 5 vol.%), no evidence of fracture was found in any of the pipe fittings, whereas at higher sigma-phase levels (σ > 5 vol.%), fracture occurred in all tests. At the highest sigma-phase level (σ ≈ 15 vol.%), extensive fracture and crack growth took place independent of the loading rate.


    Access

    Access via TIB

    Check availability in my library

    Order at Subito €


    Export, share and cite



    Title :

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



    Published in:

    Publication date :

    2016




    Type of media :

    Article (Journal)


    Type of material :

    Print


    Language :

    English



    Classification :

    BKL:    50.92 / 50.92 Meerestechnik / 55.40 / 55.40 Schiffstechnik, Schiffbau



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

    Børvik, T. / Marken, L.A. / Langseth, M. et al. | Taylor & Francis Verlag | 2016



    Steel member hoisting clamp for pipe fittings

    CHENG GONGZHENG | European Patent Office | 2020

    Free access


    AUTOMOTIVE PIPE FITTINGS

    SAE Technical Papers | 1993