Document: NRC Regulatory Guide
Document ID: e9f2f7f8-8345-4591-a596-70b7ac0be7cf
Document Type: regulatory_guide
Title: Control of Electroslag Weld Properties + HISTORY - HISTORY DG-1223 , Proposed Revision 1, published 06/2009 (Rev. 1)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML0907/ML090750626.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.34
CFR Part: 
CFR Title: 

Content:
ocument displays a currently valid OMB control number. B. DISCUSSION Background The American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code, Section III, “Nuclear Power Plant Components,”1 specifies certain requirements associated with manufacturing Class 1 and 2 components. Procedure Qualifications Section III requires adherence to ASME Boiler and Pressure Vessel Code, Section IX, “Welding Qualifications,” which includes the requirements for the procedure qualification for welds. Review of the requirements of the procedure qualification stated in Section IX indicates that supplementary requirements are desirable to provide assurance of adequate weld metal properties when the electroslag welding process is used. The assurance of satisfactory electroslag welds for low-alloy steel and stainless steel can be increased by maintaining a weld metal solidification (dendritic) pattern with a strong intergranular bond in the center of the weld. A number of electroslag welding process variables, such as slag pool depth, electrode feed rate and oscillation, current, voltage, and slag conductivity, have been shown to influence the weld metal solidification pattern. If the combination of process variables results in a deep pool of molten weld metal, the crystalline (dendritic) growth direction from the pool sides will join at an obtuse angle in the center of the weld, and cracks may develop because of the weaker centerline bond between dendrites. Section I-I in Figure A of this guide illustrates the dendritic growth pattern. A combination of process variables resulting in a shallow pool of molten weld metal will promote a dendritic growth pattern with an acute joining angle and will result in a strong centerline bond. Acceptable welds should show a dendritic freezing pattern with a joining angle of less than 90 degrees in the weld center. Tests should be made to ensure that the acceptable weld metal solidification pattern specified above is