Hydrogen Induced Cracking of a Dissimilar Weld in a Hydrogen Manufacturing Plant

2019 ◽  
Author(s):  
Neil Park ◽  
Jorge Penso
Keyword(s):  
Dew Point ◽  
Co2 Corrosion ◽  
Manufacturing Plant ◽  
Boundary Zone ◽  
Cold Wall ◽  
Fusion Boundary ◽  
Co Chemisorption ◽  
Dissimilar Weld ◽  
Failure Investigation ◽  
Hydrogen Induced Cracking

Abstract A hydrogen manufacturing plant experienced circumferential cracking at the dissimilar weld on the outlet header. The outlet header was a cold wall design and the dissimilar weld was between HP40 modified and carbon ½ Mo steels. The resultant failure investigation found the cause to be hydrogen induced cracking of the dissimilar weld at the fusion boundary zone. The hydrogen was generated from the CO2 corrosion which occurred due to operating the tubes below the dew point and the hydrogen was trapped in the steel by the CO chemisorption onto the steel. The following paper outlines the failure investigation and the fitness for service conducted to maintain the running of the plant.

scholarly journals USING WIRE BEAM ELECTRODE (WBE) TO EVALUATE THE CORROSION BEHAVIOR OF ND STEEL IN ACID MEDIUM

2020 ◽  
Vol 1 (2) ◽  
pp. 27-30
Author(s):  
Bo Zhao ◽  
Yuxin Yu ◽  
Jing Guo ◽  
Tianyu Zhou ◽  
Shiwen Zou ◽  
...  
Keyword(s):  
Partial Pressure ◽  
Corrosion Behavior ◽  
Ring Structure ◽  
Corrosion Products ◽  
Dew Point ◽  
Co2 Corrosion ◽  
Uniform Corrosion ◽  
Corrosion Morphology ◽  
Co2 Partial Pressure ◽  
Wire Beam Electrode

In this article, wire beam electrode (WBE) was used to evaluate the corrosion behavior of ND steel in environmental acid atmosphere with different partial pressure of CO2. Meanwhile, corrosion products and surface morphology analysis also used to support this research. The results showed that the corrosion behavior began from the edge of droplet in dew point corrosion, and gradually spread to the center of it. The spread speed would be increasing with CO2 partial pressure enhance, which was 24h in 5% CO2 and 4h in 50% CO2. Corrosion current density in the edge of droplet can form the “cathode-anode-cathode ring” structure and disappears gradually as the corrosion time was going. Corrosion morphology observation results showed three ring shapes region and different elemental composition of different corrosion products, which is correspondence with the “cathode-anode We-cathode ring” structure measured in WBE experiments. The results showed that the reaction gradually transferred to the uniform corrosion on electrode surface when the dew point corrosion reaction reaching the late stage. It comes from the dissolution, diffusion and reaction of gaseous corrosion medium of CO2 and O2.

A Study of Thermal Aging Effects on Microstructures of Dissimilar Metal Weldment

2013 ◽  
Author(s):  
Kyoung Joon Choi ◽  
Jong Jin Kim ◽  
Ji Hyun Kim
Keyword(s):  
Weld Metal ◽  
Alloy Steel ◽  
Thermal Aging ◽  
Base Alloy ◽  
Boundary Region ◽  
Low Alloy Steel ◽  
Aging Effects ◽  
Fusion Boundary ◽  
Dissimilar Weld ◽  
Dissimilar Metal

Characterizations of microstructure and mechanical property were conducted to investigate the effect of long-term thermal aging on the microstructural evolution in the fusion boundary region between weld metal and low alloy steel in dissimilar metal welds. A representative dissimilar weld mock-up made of Alloy 690-Alloy 152-A533 Gr. B was fabricated and aged at 450°C for 5,500 hours. It was observed that the region near the fusion boundary was generally divided into several regions including dilution zone in the Ni-base alloy weld metal, fusion boundary, and heat-affected zone in the low alloy steel. A steep gradient was shown in the chemical composition profile across the interface between A533 Gr. B and Alloy 152. The precipitation of carbides was also observed along and near the fusion boundary of aged dissimilar metal joints. It was also found that the precipitation of Cr carbides was enhanced by the thermal aging near the fusion boundary.

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