Omission of Intermediate Postweld Heat Treatment (PWHT) by Utilizing Low-Temperature PWHT for Welds in Pressure Vessels

2009 ◽  
pp. 418-418-33 ◽  
Author(s):  
E Takahashi ◽  
K Iwai
Keyword(s):  
Heat Treatment ◽  
Low Temperature ◽  
Postweld Heat Treatment ◽  
Pressure Vessels ◽  
Postweld Heat

A Thermal Stress Mitigation Technique for Local Postweld Heat Treatment of Welds in Pressure Vessels

2015 ◽  
Vol 137 (5) ◽  
Author(s):  
Chunge Nie ◽  
Pingsha Dong
Keyword(s):  
Heat Treatment ◽  
Thermal Stresses ◽  
Postweld Heat Treatment ◽  
Pressure Vessels ◽  
Cylindrical Vessel ◽  
Spherical Vessel ◽  
Novel Method ◽  
Bull's Eye ◽  
Recommended Guidelines ◽  
Postweld Heat

This paper introduces a novel method for effectively mitigating high thermal stresses caused during local postweld heat treatment (PWHT) of welds in pressure vessels on which traditional heating method such as bull's eye heating arrangement has been proven difficult in meeting Code requirements for avoiding “harmful” temperature gradients. The method involves the use of a secondary heat band (SHB) that strategically positioned at some distance away from primary PWHT heat band (HB) in terms of vessel characteristic length parameter Rt, where R is vessel radius and t wall thickness. The basic principles associated with the SHB based technique are first demonstrated on a simple straight pipe girth weld configuration. Then, applications for treating nozzle welds in more complex spherical vessel, cylindrical vessel, and at end of cylindrical vessel are presented. Finally, a set of recommended guidelines are provided for defining both the SHB size and location for performing local PWHT on welds in three major nozzle/vessel weld configurations.

scholarly journals Analysis on the Operation Methods of Rail Welding and Postweld Heat Treatment in the Track Change Overhaul of Existing Railway Lines

2022 ◽  
Vol 2152 (1) ◽  
pp. 012018
Author(s):  
Qi Feng ◽  
Hongtu Song
Keyword(s):  
Heat Treatment ◽  
Low Temperature ◽  
Treatment Process ◽  
Operation Mode ◽  
Postweld Heat Treatment ◽  
Heat Treatment Process ◽  
Existing Problems ◽  
On Line ◽  
Quality Risk ◽  
Postweld Heat

Abstract Based on the analysis of operation methods of rail welding and postweld heat treatment in the track change overhaul of existing railway lines at home and abroad, this paper puts forward the existing problems in the operation methods of off-line welding and on-line welding in China, and puts forward the solutions to the existing problems. When this operation mode is used for on-line welding, it can reduce the quality risk in the heat treatment process of low-temperature locking joint; in case of broken track and urgent repair of broken track, this method can eliminate secondary shunting and facilitate the recovery of the line as soon as possible.

A Guide for Determining Postweld Heat Treatment Requirements for ASME Code Section VIII Pressure Vessels

1984 ◽  
Vol 106 (1) ◽  
pp. 115-123
Author(s):  
D. D. Carpenter
Keyword(s):  
Heat Treatment ◽  
Decision Trees ◽  
Postweld Heat Treatment ◽  
Pressure Vessels ◽  
Quick Method ◽  
Asme Code ◽  
Section Viii ◽  
Postweld Heat

This paper discusses some uncertainties that occasionally arise when considering postweld heat treatment and presents, by the use of decision trees, a quick method for determining whether or not postweld heat treatment is required.

Effect of postweld heat treatment on interface microstructure and metallurgical properties of explosively welded bronze—carbon steel

2018 ◽  
Vol 25 (8) ◽  
pp. 1849-1861 ◽  
Author(s):  
Mohammad Reza Khanzadeh Gharahshiran ◽  
Ali Khoshakhlagh ◽  
Gholamreza Khalaj ◽  
Hamid Bakhtiari ◽  
Ali Reza Banihashemi
Keyword(s):  
Heat Treatment ◽  
Carbon Steel ◽  
Postweld Heat Treatment ◽  
Interface Microstructure ◽  
Metallurgical Properties ◽  
Postweld Heat

scholarly journals Examining Stress Relaxation in a Dissimilar Metal Weld Subjected to Postweld Heat Treatment

2018 ◽  
Vol 7 (4) ◽  
pp. 20180018
Author(s):  
K. Abburi Venkata ◽  
S. Khayatzadeh ◽  
A. Achouri ◽  
J. Araujo de Oliveira ◽  
A. N. Forsey ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Stress Relaxation ◽  
Postweld Heat Treatment ◽  
Dissimilar Metal ◽  
Dissimilar Metal Weld ◽  
Postweld Heat ◽  
Metal Weld

A Method for Applying Automatic Temperature Control to the Transient Finite Element Analysis of a Pressure Vessel Undergoing Postweld Heat Treatment

2004 ◽  
Author(s):  
Michael Sciascia
Keyword(s):  
Heat Treatment ◽  
Finite Element ◽  
Boundary Conditions ◽  
Temperature Profile ◽  
Pressure Vessel ◽  
Postweld Heat Treatment ◽  
Transient Temperature ◽  
Element Analysis ◽  
Heater Power ◽  
Postweld Heat

For complex finite element problems it is often desirable to prescribe boundary conditions that are difficult to quantify. The analysis of a pressure vessel undergoing postweld heat treatment (PWHT) is an example of such a problem. The PWHT process is governed by Code rules, but the temperature and gradient requirements they impose are not sufficient to precisely describe the complete vessel temperature profile. The imposition of such a profile in the analysis results in uncertainty and errors. A suitable but difficult approach is to specify heater power instead of temperatures, letting the solver determine the temperature profile. Unfortunately, the individual heater power levels necessary to meet the Code requirements are usually not known in advance. Determining the power levels necessary is particularly difficult if a transient solution is required. A means of actively controlling the heaters during the FEA solution is requirement for this approach. A simple and adaptive control algorithm was incorporated into the FEA solver via its scripting capability. Heat flux boundary conditions (heater power) were applied instead of transient temperature boundary conditions. Heater power levels were optimized to achieve predetermined time/temperature goals as the solution proceeded. The algorithm described was successfully applied to a pressure vessel PWHT with 14 zones of control. The approach may be adapted to other problems and boundary conditions.

Effect of Postweld Heat Treatment Conditions on Microstructure of 9Cr-1Mo-V Steel Welds for Pressure Vessel

2017 ◽  
Author(s):  
Hidenori Terasaki ◽  
Tomohiro Tanaka ◽  
Masamitsu Abe ◽  
Mitsuyoshi Nakatani
Keyword(s):  
Electron Microscopy ◽  
Heat Treatment ◽  
Weld Metal ◽  
Postweld Heat Treatment ◽  
Pressure Vessels ◽  
Dislocation Network ◽  
Precipitation Behavior ◽  
Treatment Conditions ◽  
Scanning Transmission ◽  
The Difference

We investigated the effects of post-weld heat treatment conditions on the microstructure of the multi-pass submerged arc weld metal of 9Cr-1Mo-V steel used in pressure vessels. The microstructural properties were analyzed under three conditions (as-weld, Larson-Miller parameter (LMP) = 21.38 × 103, and LMP = 21.99 × 103). The precipitation behavior was observed using scanning electron microscopy, and the difference in precipitation behavior in the “as-welded” and “reheated” regions of the prepared multi-pass weld metal was clarified at the different LMP values. The precipitate was analyzed using scanning transmission electron microscopy. An oxide and two types of precipitates were identified, and a dislocation network pinned by MX-type carbides was visualized under the low-LMP condition. The effects of LMP on the effective grain size and dislocation amount were also evaluated using electron back-scattering diffraction. All microstructural change along the LMP had a positive effect on the toughness of weld metal.

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