Document: NRC Regulatory Guide
Document ID: ff075502-711b-4416-bfc8-a2a645bfe130
Document Type: regulatory_guide
Title: Nonmetallic Thermal Insulation for Austenitic Stainless Steel + HISTORY - HISTORY DG-1312 , Proposed Revision 1, published 09/2014 (Rev. 1)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML1407/ML14079A671.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.36
CFR Part: 
CFR Title: 

Content:
ontaminants present in the thermal insulation may be leached by these liquids and deposited on the stainless steel surfaces. Extensive test programs by Dana (Ref. 2) demonstrated that stress-corrosion cracking of both unsensitized and sensitized austenitic stainless steel can be induced by chloride or fluoride ions leached from many representative thermal insulation materials. Whorlow, et. al. (Ref. 3) has further shown that leachable sodium and silicate ions have differing qualities for inhibiting the adverse effects of the chloride and fluoride ions. Controls should be exercised to assure that nonmetallic thermal insulations employed in nuclear power plants do not contribute significantly to stress corrosion of stainless steel. A quality assurance program should be implemented at all steps from manufacturing through installation to minimize pickup of contaminants from external sources. To provide reasonable assurance that nonmetallic thermal insulation will not contribute to stress- corrosion cracking of stainless steels, each type1 of insulating material should be evaluated in conditions similar to those routinely found in reactor operations, to meet the requirements of American Society for Testing and Materials (ASTM) C795, “Standard Specification for Thermal Insulation for Use in Contact with Austenitic Stainless Steel,” (Ref. 4). A Preproduction Corrosion Test in accordance with ASTM 1 Type means material of similar composition, form and class, of consistent quality, formulation and manufacturing process. DG-1312 Page 3 C692, “Standard Test Method for Evaluating the Influence of Thermal Insulation on External Stress Corrosion Cracking Tendency of Austenitic Stainless Steel,” (Ref. 5) and a chemical analysis acceptance test for the material in accordance with ASTM C871, “Test Method for Chemical Analysis of Thermal Insulation Materials for Leachable Chloride, Fluoride, Silicate and Sodium Ions” (Ref. 6) is required to meet ASTM C795 for