KR-20260064507-A - Copper shoe for high heat input welding in LPG or ammonia carriers and EGW or ESW welding carriage including the same

Abstract

A copper dipping plate for high heat input welding for LPG or ammonia carriers and an EGW or ESW welding carriage including the same are disclosed. The copper dipping plate for high heat input welding for LPG or ammonia carriers according to the present invention comprises a body portion forming an outer shape and a cooling channel formed to penetrate the interior of the body portion and for transporting cooling water to cool a fusion line (FL) and a heat-affected zone (HAZ).

Inventors

• 이현준
• 김병철
• 장길수
• 백성진

Assignees

• 에이치디한국조선해양 주식회사
• 에이치디현대중공업 주식회사
• 에이치디현대삼호 주식회사

Dates

Publication Date

20260507

Application Date

20250910

Priority Date

20241031

Claims (7)

1. A body part forming the outer shape; and, It includes a cooling channel formed to penetrate the interior of the body portion and for transporting cooling water to cool the fusion line (FL) and the heat-affected zone (HAZ); Copper condenser for high heat input welding for LPG or ammonia carriers, characterized by the above cooling channel independently cooling each of the fusion lines on both sides of the weld.
2. In paragraph 1, The above cooling channel is, A first cooling channel provided to cool a fusion line on one side, and Copper condenser for high heat input welding for LPG or ammonia carriers, characterized by including a second cooling channel that is independently arranged at a certain distance from the first cooling channel and is provided to cool the other fusion line.
3. In paragraph 2, Based on the surface gap (C) of the improved surface, the distance (A) between fusion lines is C+2mm or more and C+10mm or less, and Copper condenser for high heat input welding for LPG or ammonia carriers, characterized in that the separation distance (D) between the first cooling channel and the second cooling channel is set to a range of A-6mm or more and A+2mm or less.
4. In paragraph 1, The above body part is, Copper lining for high heat input welding for LPG or ammonia carriers, characterized by having a length of 80 mm or more in the direction of welding.
5. In paragraph 1, The above cooling channel is, Copper condenser for high heat input welding for LPG or ammonia carriers, characterized by including a flow control valve for each flow path to independently control the flow rate of the cooling water.
6. An EGW welding carriage comprising a copper lining for high heat input welding for an LPG or ammonia carrier according to any one of claims 1 to 4.
7. An ESW welding carriage comprising a copper lining for high heat input welding for an LPG or ammonia carrier according to any one of claims 1 to 4.

Description

Copper shoe for high heat input welding in LPG or ammonia carriers and EGW or ESW welding carriage including the same The present invention relates to a copper rig for high heat input welding for LPG or ammonia carriers and an EGW or ESW welding carriage including the same, and more specifically, to a copper rig with an independent cooling channel spaced apart to selectively cool the area in order to improve the impact toughness of the fusion line and the heat-affected zone, and a welding carriage including the same. Generally, since the hull and tank structures of LPG or ammonia carriers must maintain stability even in cryogenic environments, high-quality welding is essential for joining these components. Various welding methods are used for these vessels, including Flux Cored Arc Welding (FCAW), Submerged Arc Welding (SAW), Electro Gas Welding (EGW), and Electro Slag Welding (ESW). In particular, at shipbuilding sites, the use of automated high-heat input welding processes such as SAW and EGW, which can be automated, is gradually expanding to ensure work efficiency and quality. However, high-heat input automated welding processes present a problem in that the large heat input makes it difficult to control the heat of the fusion line and the surrounding heat-affected zone (HAZ) formed during welding. In particular, if the arc heat source is excessively concentrated on the base metal or if molten metal remains uncooled, the microstructure may coarsen, leading to a decrease in impact toughness. This problem can result in rejection at the 5mm or 10mm position during impact tests conducted according to classification society standards, and poses a greater burden on quality assurance, especially for LPG or ammonia carriers that require cryogenic environments below -60℃. Therefore, there is a need for a technical alternative that can stably secure impact toughness of the weld through localized heat and cooling control while maintaining the productivity and efficiency of high-heat input automated welding. To address these issues, various technical approaches are required to ensure cryogenic impact toughness even when applying automated high-heat input welding processes. For example, in the EGW process, by applying Direct Current Electrode Negative (DCEN) polarity to ensure that arc electrons are transferred toward the welding wire rather than the base metal, excessive penetration of welding heat into the base metal can be prevented, and heat input can be concentrated on the wire. Additionally, by optimizing the feed rate and welding waveform to control heat input and ensure arc stability, microstructure coarsening in the fusion line and heat-affected zone can be suppressed, thereby improving impact toughness. In the case of the ESW process, by controlling the ratio between the feed speed and the welding current within an appropriate range, excessive heat input can be prevented and the thermal impact on the weld area minimized. Furthermore, the system can be configured to enable stable feed through a digital feeder and dual roller drive. This enables the realization of an automated process applicable to vertical welding of extremely thick materials, while simultaneously ensuring uniformity in welding quality and productivity. In addition, copper quenching technology that selectively cools the relevant areas is required as a method to fundamentally resolve the problem of impact toughness degradation in the fusion line and heat-affected zone. In particular, by arranging independent cooling channels centered on both sides of the fusion line formed during welding and optimizing the spacing between cooling channels by considering the beveled surface opening width and the distance between fusion lines, rapid cooling near the HAZ after welding can be induced and microstructure formation promoted. Through this, it is possible to secure toughness exceeding classification society standards in the F/L to F/L+1mm section, where impact toughness is most vulnerable, and effective thermal control can be achieved while preventing unnecessary cooling of the molten metal. Therefore, there is an urgent need to develop high-heat input welding technology that can ensure welding quality suitable for cryogenic environments while simultaneously satisfying the productivity of automated processes. FIG. 1 is a configuration diagram of a high heat input EGW welding system for an LPG or ammonia carrier according to one embodiment of the present invention. FIG. 2 is a conceptual diagram comparing cases where the welding power applied to the EGW is set to the polarity of the conventional DCEP and the DCEN of the present invention, respectively. Figure 3 is a graph comparing the switching frequency of a conventional welding power supply applied to an EGW and the switching frequency of the welding power supply of the present invention. Figure 4 is a graph comparing the ratio of the conventional feed rate and welding current applied to EGW with th