Steam Generator Grade P91 Steel Components Creep-Assessment By Test After Extended Service

2021 ◽  
Author(s):  
Ottaviano Grisolia ◽  
Lorenzo Scano ◽  
Francesco Piccini ◽  
Antonietta Lo Conte ◽  
Massimiliano De Agostinis ◽  
...  
Keyword(s):  
High Temperature ◽  
Weld Metal ◽  
Steam Generator ◽  
Microstructure Evolution ◽  
Creep Strength ◽  
Operation Temperature ◽  
Creep Analysis ◽  
Creep Cavitation ◽  
Weld Metal Microstructure ◽  
Metal Microstructure

Abstract Previous study carried out creep analysis for steam generator high-temperature-section two components, outflow tubing and manifold of the superheater harp: they may have been critical because of the long continued service (109,000 hours or twelve years) and loading conditions, including maximum operation temperature (565°C) and applied stress (65 MPa). Metallographic methods by replica had showed no evidence of the creep cavitation in all the positions considered for both tubing and manifold. In particular, they had not found any cavitation or phases affecting creep strength of the material in the base, HAZ and weld metal microstructure. Now, present study carries out investigation for the two components based on the next plant outage outcome, after further 20,000-hours service. Both metallographic methods and hardness measurements’ results would compare with previous ones providing microstructure evolution in the period.

Steam Generator Grade P91 Steel Components Creep-Assessment Through a Procedure for the Italian Code Application and Comparison With the ECCC Recommendations, American Standard

2017 ◽  
Author(s):  
Ottaviano Grisolia ◽  
Lorenzo Scano
Keyword(s):  
High Temperature ◽  
Steam Generator ◽  
Polynomial Function ◽  
Steam Generators ◽  
Steel Microstructure ◽  
Operation Temperature ◽  
Creep Analysis ◽  
Material Creep ◽  
Level 3 ◽  
American Standard

ASTM A 335-Grade P91 components of steam generators may be critical because of possible steel microstructure changes and/or embrittlement due to the FATT increase during service at high temperature: both phenomena may worsen the material creep behavior globally. Operation temperatures below 600°C such as in the worked case considered herein should be less critical; nevertheless, the worked case plan has included additional controls on microstructure also to have a reference for the future. Present study considers for the worked case steam generator the creep analysis of high-temperature-section (superheater / reheater) two components, outflow tubing and manifold: they may be critical because of the long continued service (110,000 hours or twelve years) and loading conditions (maximum operation temperature and applied stress at the intersection). Aim of the work is to compare life results from the Italian creep code with those predicted by the API 579-1; it also checks compatibility of results from the polynomial models in Italian, ECCC and API 579-1 procedures. Life results based on the Italian-code polynomial function are consistent with those based on the polynomial function proposed in ECCC: With preliminary stresses from pressure formulas, life estimates are a bit more conservative than the ECCC model’s. Finally, life results obtained through the API 579-1 Level 3 assessment appear consistent with those predicted by the Italian creep code, ECCC recommendations application.

Effect of Environment on Sn Whisker Growth during Welding of Electronic Wires

2015 ◽  
Vol 1110 ◽  
pp. 235-240 ◽  
Author(s):  
Tomomi Sakakida ◽  
Tatsuo Kubouchi ◽  
Yasuyuki Miyano ◽  
Mamoru Takahashi ◽  
Osamu Kamiya
Keyword(s):  
Energy Balance ◽  
Weld Metal ◽  
Whisker Growth ◽  
Weld Zone ◽  
Electrolytic Capacitor ◽  
Sn Whisker ◽  
Sn Whiskers ◽  
Weld Metal Microstructure ◽  
Short Circuits ◽  
Metal Microstructure

In Pb-free Al-Sn welding of electrolytic parts, single-crystal Sn whiskers easily form and can cause problems such as short circuits. Here we report that the growth of Sn whiskers in the weld zone of Al electrolytic condenser leads was suppressed in a vacuum environment. We examined the effect of the environment and weld metal microstructure in order to understand how to control and prevent whisker growth. In vacuum, the weld zone did not form whiskers after more than 100 h, whereas in air, whiskers grew within several hours. This suggests that whiskers require oxygen to form. The growth can be explained by the energy balance between the potential energy of the weld metal and the surface energy of the whisker. Our results will contribute to developing techniques for suppressing the formation of Sn whiskers during the percussion welding of Al electrolytic capacitor leads.

Effect of Ti on the Microstructures and Toughness of TMCP-600 Steel Weld Metals

2013 ◽  
Vol 746 ◽  
pp. 462-466
Author(s):  
Jin Hyun Koh ◽  
Bok Su Jang
Keyword(s):  
Weld Metal ◽  
Impact Energy ◽  
Acicular Ferrite ◽  
Gas Metal Arc Welding ◽  
Control Process ◽  
High Strength ◽  
Weld Metal Microstructure ◽  
Metal Microstructure ◽  
The Impact ◽  
Ti Content

The Ti addition effect on the characteristics of weld metal, such as impact energy, microstructure and nonmetallic inclusions, was investigated to develop a suitable gas metal arc welding wire for the high strength of TMCP (Thermo Mechanical Control Process)-600 steel. The fraction of acicular ferrite which was known to be a favorable weld metal microstructure for toughness was increased with Ti content from 0.002% to 0.025%, The impact energy of weld metal was increased whereas the ductile to brittle transition temperature was decreased with increasing Ti content. The size of nonmetallic inclusion was decreased while the density of inclusions was decreased with increasing Ti content. It was found that Ti content on the weld metal toughness had a plus effect by increasing the fraction of acicular ferrite in the weld metal microstructure.

A Decade of Progress in Underwater Wet Welding Using the SMAW Process (1990-2003)

2004 ◽  
Author(s):  
Stephen Liu
Keyword(s):  
Weld Metal ◽  
Nickel Content ◽  
Cost Savings ◽  
Significant Cost ◽  
Electrode Coating ◽  
Underwater Wet Welding ◽  
Recent Developments ◽  
Weld Metal Microstructure ◽  
Metal Microstructure ◽  
Repair Techniques

It is well established that underwater wet welding (UWW) offers significant cost savings over other repair techniques for submerged structures such as petroleum production platforms, ships, and piers. Due to the deleterious effect of increased pressure on weld quality, innovative consumables are required for the production of quality wet welds. Manganese was added to the electrode coating to replenish its loss from the weld pool. Titanium and boron were added to control the molten metal oxygen potential and refine the as-solidified and reheated weld metal microstructure. Rare-earth metals (REM) were added to control the weld metal oxygen content. Finally, weld metal nickel content was optimized to improve impact toughness. Selected results of these approaches are presented in this work. These recent developments clearly demonstrate that it is possible to achieve significant progresses in wet welding using shielded metal arc (SMA) consumables, if these are designed following sound metallurgical principles.

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