Standard Guide for Evaluating Polymeric Lining Systems for Water Immersion in Coating Service Level III Safety-Related Applications on Metal Substrates

Importancia y uso:

5.1 Safety-related service water system (SWS) components are designed to provide adequate cooling to equipment essential to the safe operation and shutdown of the plant. Linings in these systems are installed to maintain the integrity of the system components by preventing corrosion and erosion of the metal materials of construction. Linings on SWS surfaces upstream of components, including heat exchangers, orifice plates, strainers, and valves, the detachment of which may affect safe-plant operation or shutdown, may be considered safety-related, depending on plant-specific licensing commitments and design bases.

5.2 The testing presented in this guide is used to provide reasonable assurance that the linings, when properly applied, will be suitable for the intended service by preventing corrosion and erosion for some extended period of time. Additionally, the test data derived allows development of schedules, methods, and techniques for assessing the condition of the lining materials (see Guide D7167). The ultimate objective of the testing is to avoid lining failures that could result in blockage of equipment, such as piping or heat transfer components, preventing the system or component from performing its intended safety function.

5.3 It is expected that this guide will be used by:

5.3.1 Lining manufacturers for comparing specific products and systems and to establish a qualification basis for recommended linings and

5.3.2 End users seeking a consistent design basis for candidate coating systems.

5.4 In the event of conflict, users of this guide must recognize that the licensee's plant-specific quality assurance program and licensing commitments shall prevail with respect to the selection process for and qualification of CSL III lining materials.

5.5 Operating experience has shown that the most severe operating conditions with respect to heat exchanger linings occur on pass partitions. A phenomenon known as the “cold wall effect” accelerates moisture permeation through a coating applied to the warmer side of a partition that separates fluids at two different temperatures. The thickness and permeability of the lining are key variables affecting the ability of a lining to withstand cold wall blistering.

5.5.1 This effect is particularly pronounced when the separated fluids are water, though the effect will occur when only air is on the other side, for example, an outdoor tank filled with warm liquid. A heat exchanger pass partition represents geometry uniquely vulnerable to the water-to-water maximized temperature differentials (ΔTs) that drive the cold wall effect.

5.5.2 Pass partitions separate relatively cold incoming cooling water from the discharge water warmed by the heat exchanger's thermal duty. Improperly designed coatings will exhibit moisture permeation to the substrate accelerated by the cold-wall effect. Many instances of premature pass partition warm-side blistering have been noted in the nuclear industry. Such degradation has also been seen on lined cover plate and channel barrel segments that reflect water-to-air configurations.

5.6 Large water-to-water ΔTs are known to be the most severe design condition. The test device used to replicate ΔT configurations is known as an “Atlas cell.” Atlas cell testing is governed by industry standard test methodologies (Test Method C868 and NACE TM0174). A lining proven suitable for the most severe hypothesized ΔT would also be suitable for service on other waterside surfaces.

5.7 Plant cooling water varies in composition and temperature seasonally. For purposes of standardization, demineralized water is used in Atlas cell exposures rather than raw plant water. It is generally accepted in polymeric coatings technology that low-conductivity water (deionized or demineralized) is more aggressive with respect to its ability to permeate linings than raw water. Thus, stipulating use of low-conductivity water as the test medium is considered conservative.

Subcomité:

D33.02

Referida por:

D3912-10R23, D7167-12R18, D5144-08R21

Volúmen:

06.02

Número ICS:

23.040.01 (Pipeline components in general. Pipelines)

Palabras clave:

Coating Service Level III; CSL III; cold-wall effect; lining systems; metal substrates; nuclear; polymeric material; safety-related service water; service water systems;