ISO/TC 156/WG 9 - Corrosion testing of materials for power generation

The document specifies a method for undertaking uniaxial constant load testing of the susceptibility of a metal, or an alloy, to stress corrosion cracking (SCC) in high-purity water environments at high temperature (above the boiling point of water at normal pressures) and pressure. The test method is particularly applicable to simulated primary water environments of light water reactors (LWRs). The test method enables assessment of the relative resistance to SCC of a material in different environments and the comparative resistance of different materials (using the same environment, specimen dimensions and loading). The terms “metal” and “alloy”, as used in the document, include weld metals and weld heat affected zones.

This document specifies: a) the determination of mass gain; b) the surface inspection of products of zirconium and its alloys when corrosion is tested in water at 360 °C or in steam at or above 400 °C; c) the performance of tests in steam at 10,3 MPa. This document is applicable to wrought products, castings, powder metallurgy products and weld metals. This method has been widely used in the development of new alloys, heat-treating practices and for the evaluation of welding techniques. It is applicable for use in its entirety to the extent specified for a product acceptance test, rather than merely a means of assessing performance in service.

This document specifies a test method for determining the stress corrosion crack (SCC) growth rate of steels and alloys under static-load conditions in high-temperature water, such as the simulated water environment of light water reactors. The crack length of the specimen is monitored by a potential drop method (PDM) during the test in an autoclave. The test method is applicable to stainless steels, nickel base alloys, low alloy steels, carbon steels and other alloys.

This document specifies procedures for designing, preparing and using reversed U-bend (RUB) test specimens for investigating the susceptibility of the metal to stress corrosion cracking. The term "metal" as used in this document includes alloys.

ISO 19280:2017 specifies a methodology for ranking the crevice corrosion resistance of stainless steels and related alloys when exposed to oxidizing chloride solution. This document allows the measurement of critical crevice temperatures of tube/rod type specimens equal to those of plate type ones made up of the same material by chemical initiation of crevice corrosion, but not by the electrochemical method of ISO 18070. The test method in this document defines the apparatus and the procedure used to measure the temperature of crevice corrosion initiated in pipes and tubes using cylindrical specimens. This method has also been proved to apply to plate type specimens.

ISO 17918:2015 specifies procedures of on-site detection and evaluation in order to determine the effects of material deterioration such as material loss from the components and structures that are sensitive to selective corrosion in industrial facilities, including nuclear power plants. The methodology involves visual inspection and hardness measurements in situ complemented by sample removal. These procedures include (a) representative sampling of components sensitive to selective corrosion, (b) the visual inspection, and (c) the hardness test, respectively. For an exact analysis, additional laboratory testing is recommended. The methodology is most applicable to grey cast iron and copper alloy with more than 15 % zinc. Extension to other alloys requires supportive evidence of validation. Assessment criteria orientated to the nuclear power plant application during the past five years before the end of extended operation define the necessity for further engineering evaluation and action like, for example, further sampling, higher frequency of inspection, and component repair or exchange. This specification is not applicable for components used where the representative sampling of surfaces in contact to the fluid is not detectable optically or detected with the portable hardness tester. Also, in case of non-representative component selection like in HVAC or building service application, this specification is not applicable. For components not used in nuclear power plant, the assessment criteria have to be agreed by the parties. Assessment criteria of hardness test alone is not applicable to the evaluation of structural integrity of Al-bronze, NAB, and Cu-Ni.

ISO 12732:2006 specifies the method for measuring the degree of sensitization (DOS) in stainless steel and nickel-based alloys using the Double Loop Electrochemical Potentiokinetic Reactivation (DL-EPR) test (based on Cihal's method). The method may be used for the quantitative assessment of deleterious thermal effects resulting in the formation of alloy-element-depleted zones at grain boundaries or in the matrix. However, attention should be paid when testing heat-affected weld zones, due to possible non-uniform distribution of sensitized zones along the fusion lines. The results of the test can be used as an index to identify the potential susceptibility of stainless steel and nickel-based alloys to intergranular corrosion, pitting corrosion, and intergranular-stress corrosion cracking, but prediction of these corrosion modes depends on complementary specific testing. ISO 12732:2006 describes the general methodology and gives examples of suitable test exposure conditions for specific alloys.

ISO 7539-10:2013 covers procedures for designing, preparing and using reversed U-bend (RUB) test specimens for investigating the susceptibility of the metal to stress corrosion cracking. The term "metal" as used in this standard includes alloys.

Specifies methods for the determination of mass gain and for the surface inspection of products of zirconium and its alloys when corrosion tested in water at 360 °C or in steam at or above 400 °C. Applicable to wrought products, castings and powder metallurgical products.