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This paper describes an experimental analysis of residual stresses conducted on thick and high constraint low alloy Cr-Mo-V welded joints, by the method called hole drill test. Data was collected on test specimens with nozzle geometry, welded with SAW process. The results were analyzed by comparison with manufacture requirements of pressure vessels for critical applications. In light of data collected, it was discussed the need of an Intermediate Stress Relief (ISR) heat treatment for this joint, required by applicable regulations and standards. [ABSTRACT FROM AUTHOR]

Owing to restricted energy resources and the worldwide ambitions to reduce CO2emissions, renewable energy sources, such as wind energy, are gaining economical interest and promise great growth potential. This is closely connected with the increase of plant unit sizes. The wall thickness of the tower construction is rising accordingly and leads to increasing costs for the joining technology. The rising number of weld passes for submerged arc welding (SAW) leads to rising process times and high filler material consumption. The employment of non-vacuum electron beam welding (NVEBW) can significantly reduce the number of passes, the welding time, and the filler consumption. A substantial aspect of the control of the welding process is the formation of solidification cracks. Formation mechanisms and preventions methods such as preheating, alloying, and full penetration welding will be presented and experimentally backed up. The subsequent application of the SAW and NVEBW processes will be compared to standard multi-pass SAW for an exemplary weld of 30 mm thick high-strength steel. An additional aim of current research is the overall reduction of the wall thickness of wind turbine towers applying high-strength steels. Here, it is of chief concern to preserve the advantages of the material. [ABSTRACT FROM AUTHOR]

EST Plant (Eni Slurry Technology) consists of about 300 pressure vessels in the following principal units and section: * EST unit (unit 90); * Hydrogen production plant (Unit 95); * SWS sulphur recovery and tail gas treatment (Unit 92 and 94). More than 100 "critical" equipments exist in the EST complex, divided in units and sections on the basis of their type of service. In detail, the considered critical items include: carbon steel and low alloy steels heavy wall pressure vessels for high temperature, high-pressure hydrogen service; carbon steel pressure vessels in sour (wet H^S service) and amine service. For fabrication of such "critical" items special base materials and filler metals were adopted according to specific material requirement, special welding processes and fabrication sequences (including advanced automatic systems for non destrucutive testing) were used. This paper shows an overview on some critical aspects and experience of fabrication of main "critical" equipments of EST Plant. [ABSTRACT FROM AUTHOR]

The American designation T/P92 used for tubes and pipe, respectively, indicates a creep enhanced ferritic steel (CSEF) that was originally developed by Nippon Steel under the name NF616 as an alternative to Grade 91. This grade is also referred to as Grade 92 and is available under the European designation XIOCrWMoVNb9-2 (included in EN 10216-2) as well as American designations such as ASTM A213 T92, A335 P92, A387 Gr92, A182 F92 andA369 FP92. In general, welding of P92 and similar CSEF grades is considered rather straightforward, provided that the correct welding procedures, filler metal and heating cycles are applied by welder with suitable skills. A review of published data on requirements to be considered when developing welding procedures for Grade 92 is presented in Sections 1 and 2 and summarised in Table 2. With regard to filler metals, commercially available matching grades are tabulated in Table 1. In addition, welding parameter ranges, extracted from various welding procedure specifications (WPSs) applied in industry for Grade 92 and similar, are summarised in Table 3. [ABSTRACT FROM AUTHOR]

In volumetrie NDE inspection applied on welds of high thickness hydrocracking reactors, the detection of small transverse reflectors is a priority. For this scope, manual ultrasonic test and TOFD (Time of Flight Diffraction) techniques have been strongly improved on shell circumferential butt joint welds in order to reach a high level of sensitivity and confidence in signals interpretation. On butt joint nozzle welds, due to the geometry that doesn't allow the location of TOFD probes on both sides of the weld, a combination of manual ultrasonic test and Phased Array is applied. For different reasons, these two techniques are not completely satisfactory. To increase the inspection quality, in addition to the techniques applied up to now, we have studied an application of TOFD in B-scan configuration in order to improve sensitivity and record transverse reflectors. This will determine a combination of manual UT, Phased Array (recording of longitudinal indications) and TOFD B-scan (recording of transverse indication) to completely inspect a butt joint nozzle weld. [ABSTRACT FROM AUTHOR]

This article is extract from the publication "Practical Guidelines for the Fabrication of Duplex Stainless Steels", first edition 2011, published by the International Molybdenum Association (IMOA). More in detail, the focus is on the Chapter 12 "Welding Duplex Stainless Steels", where the Authors present an updated overview concerning the most relevant issues, such as the differences existing in welding between the conventional austenitic stainless steels and the duplex ones, the selection and the fine tuning of the welding processes and the related procedures, the suggested joint preparations, the proper interpass temperature and heat input to set-up for getting a proper final phase balance, the selection of the filler material as a function of the base material and the expected weld performances. The article gives also a detailed analysis on the applicable non-arc welding and joining processes, without forgetting the post fabrication clean-up procedures, which are often critical for the performance of the welded product in service conditions, such as the corrosion resistence. The staff of Rivista Italiana della Saldatura is grateful to IMOA for the permission given to the publication of the Italian translation of this extract. [ABSTRACT FROM AUTHOR]

This paper has the target to summarize which are the fillers to be used in the pressure vessels cladding processes. We evaluate the most common requests in the customer's specifications and how to meet them while checking the results during construction. We gave great emphasis to the applications with austenitic stainless steels (series 300), without neglecting other applications such as Ni-based alloys. We evaluated the different processes to be used and the role of "b ferrite" which, besides being often a specific requirement of the customer, is also the key factor to control the cladding during the construction. We examined the various processes used in terms of thickness and dilution. The dilution is a key output, which depends on the process used and the parameters reported in the WPS. The accurate assessment of the dilution allows to choose the most suitable filler material and to avoid problems. The power source must be reliable and allow the repeatability of the process, as well as having a "duty cycle" adapted to production demands. It is important to underline that often being the surface to be plated several hundred square meters, the correct selection of the power sources reduce the cycle times and the delivery times. In fact, very often the cladding is on the production critical path. We presented some real cases, demonstrating how it is possible to meet the specification requirements with a careful analysis of a few experimental data. We dedicated a chapter to cladding repair defects subject. Cladding repairing defects need to be evaluated on a case by case basis, but in this presentation we propose some key guidelines that can be used to develop the repair specifications avoiding common problems. [ABSTRACT FROM AUTHOR]

This article deals with a criterion to extrapolate the frac-ture mechanic test results (CTOD) obtained with medium thickness welded specimens towards thicker joints. The criterion was developed by Italian Institute of Welding (IIS) starting from the available literature correlations between CTOD and J integral and taking into account the results of previous extensive fracture mechanics tests per-formed by IIS on several thicknesses. The criterion was developed within the Stura di Demon-te bridge project (Asti - Cuneo highway) in order to eva-luate the toughness of very thick (140 mm) welds joining the doubling plates of the bridge beams. In particular the extrapolation method allowed to assess the actual joints fracture toughness on the basis of CTOD tests performed on 70 mm thick specimens. [ABSTRACT FROM AUTHOR]