Integrity Assessment of the Welded Nozzle-Header Joint of the Steam Superheater.

Saved in:

Bibliographic Details
Title:	Integrity Assessment of the Welded Nozzle-Header Joint of the Steam Superheater.
Authors:	DUNĐER, Ivan¹ idunder@unisb.hr, KONJATIĆ, Pejo¹ pkonjatic@unisb.hr, KATNIĆ, Marko¹ mkatinic@unisb.hr, GELO, Ivan¹ igelo@unisb.hr
Source:	Technical Gazette / Tehnički Vjesnik. 2025, Vol. 32 Issue 4, p1324-1329. 6p.
Subjects:	Welded joints, Manufacturing defects, Structural failures, Safety, Finite element method, Structural reliability, Failure analysis, Superheaters
Abstract:	Manufacturing flaw in pressure vessels and pipelines, especially in welded joints, poses a major challenge to structural integrity and operational safety. This paper examines the effects of such flaws, focussing on a specific case study of inclusions observed at the root of welded head-nozzle joints in a steam superheater. Finite Element Analysis (FEA) is used to investigate how these flaws affect the load capacity of the pressure vessel. To simulate the behaviour of the welds under operating conditions, two scenarios are considered: one with a sharp elliptical crack between two welded nozzles and another with a full torus-shaped flaw along the entire circumference of the weld root. During the analysis, stress distributions, plastic limit loads, stress intensity factors, fracture toughness and structural integrity are assessed using the Failure Assessment Diagram (FAD) and the SINTAP method. The results show that although the presence of a sharp elliptical crack with the considered dimensions between the nozzles does not significantly affect the static strength of the structure, plastic collapse must be considered as a potential failure mechanism, especially for highly plastic materials. The FAD analysis shows that the structure can withstand the operating pressure without failing, but failure due to plastic collapse can occur at higher pressures. The study emphasises the importance of considering both fracture mechanics and the plastic failure criterion when assessing the integrity of welded components in pressure vessels. [ABSTRACT FROM AUTHOR]
	Copyright of Technical Gazette / Tehnički Vjesnik is the property of Tehnicki Vjesnik and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
Database:	Engineering Source

Description
Abstract:	Manufacturing flaw in pressure vessels and pipelines, especially in welded joints, poses a major challenge to structural integrity and operational safety. This paper examines the effects of such flaws, focussing on a specific case study of inclusions observed at the root of welded head-nozzle joints in a steam superheater. Finite Element Analysis (FEA) is used to investigate how these flaws affect the load capacity of the pressure vessel. To simulate the behaviour of the welds under operating conditions, two scenarios are considered: one with a sharp elliptical crack between two welded nozzles and another with a full torus-shaped flaw along the entire circumference of the weld root. During the analysis, stress distributions, plastic limit loads, stress intensity factors, fracture toughness and structural integrity are assessed using the Failure Assessment Diagram (FAD) and the SINTAP method. The results show that although the presence of a sharp elliptical crack with the considered dimensions between the nozzles does not significantly affect the static strength of the structure, plastic collapse must be considered as a potential failure mechanism, especially for highly plastic materials. The FAD analysis shows that the structure can withstand the operating pressure without failing, but failure due to plastic collapse can occur at higher pressures. The study emphasises the importance of considering both fracture mechanics and the plastic failure criterion when assessing the integrity of welded components in pressure vessels. [ABSTRACT FROM AUTHOR]
ISSN:	13303651
DOI:	10.17559/TV-20240521001636