Corrosion Protection of Water Treatment Equipment Pipelines and Fittings

Literature Overview

The paper by Hu Rongquan (1989), published in Electric Power Construction (Vol. 10, No. 7, pp. 28-32), provides a comprehensive overview of corrosion protection methods for water treatment equipment, pipelines, and fittings in thermal power plant applications. Authored by an engineer at Jiangxi Provincial Electric Power Design Institute, this work represents early systematic documentation of corrosion protection practices in the Chinese power generation industry. While dated, the fundamental principles remain highly relevant to modern engineering practice.

Core Technical Content

The paper addresses corrosion protection through mortar lining (砌衬) and construction techniques for water treatment systems in thermal power plants. It covers the application scope of various lining materials and provides guidance on construction methods.

Corrosion Protection Methods Covered

Construction Techniques

The paper describes the following key construction techniques for lining installation:

1. Surface preparation: Thorough cleaning, rust removal, and roughening of the steel substrate to ensure proper adhesion of the lining material.
2. Lining application: Layer-by-layer application with proper overlap and curing intervals between layers.
3. Quality inspection: Holiday detection (spark testing) for non-conductive linings, thickness measurement, and visual inspection for voids or defects.
4. Curing and seasoning: Controlled temperature and humidity conditions during the curing period to ensure proper material development.

Application Scope of Lining Materials

The paper provides guidance on material selection based on the following criteria:

• Chemical compatibility: The lining material must be resistant to the specific chemicals present in the water treatment process (acids, alkalis, reducing agents, oxidizing agents).
• Temperature resistance: Water treatment processes may involve hot solutions (e.g., demineralization water at 80-90°C), requiring linings with adequate thermal stability.
• Mechanical durability: Resistance to abrasion from suspended solids, impact from maintenance activities, and thermal cycling.
• Electrical properties: For certain applications, the lining must provide electrical insulation to prevent electrochemical corrosion of the underlying steel.

Technical Interpretation and Engineering Insights

Evolution of Corrosion Protection in Power Plant Water Systems

While this 1989 paper reflects the state of practice at that time, several important developments have occurred since then:

1. Advanced coating technologies: Modern powder-coated linings (epoxy-polyurethane, PTFE, PVDF) have largely replaced traditional mortar linings for many applications, offering superior performance with easier application.
2. Material upgrades: Duplex stainless steels (2205), super duplex (2507), and nickel-aluminum-bronze (C70600) are now commonly used for water treatment components, reducing the need for linings.
3. Cathodic protection: For buried or submerged sections of water treatment piping, cathodic protection is now routinely applied in conjunction with coatings.
4. Digital monitoring: Modern corrosion monitoring systems (ER probes, LPR probes, hydrogen flux sensors) provide real-time corrosion rate data, enabling predictive maintenance.

Relevance to Modern Pipe and Fitting Engineering

Despite its age, the paper's fundamental principles remain applicable:

• Material-medium compatibility is paramount: The core principle of selecting corrosion protection based on chemical compatibility is unchanged. Engineers must always verify material selection against the actual service environment, not just nominal design conditions.
• Construction quality determines longevity: Even the best lining material will fail if applied poorly. The emphasis on surface preparation, proper application technique, and thorough quality inspection is timeless.
• Systematic approach to corrosion protection: The paper's treatment of corrosion protection as a system (material selection + construction method + quality control + maintenance) rather than a single measure is an important engineering philosophy.

FMEA for Water Treatment Pipeline Corrosion Protection

Standards and Codes

Relevant standards for corrosion protection of water treatment systems include:

Key Questions and Reflections

Reading this paper in the context of modern practice raises several reflective points:

• Sustainability considerations: Many traditional lining materials (lead, certain epoxies) raise environmental and health concerns. Modern practice must balance corrosion protection performance with environmental sustainability and worker safety.
• Lifecycle cost analysis: The paper does not address lifecycle cost, but modern engineering practice requires comprehensive lifecycle cost analysis (LCCA) comparing the initial cost of different protection methods against their long-term maintenance and replacement costs.
• Digital transformation: Modern corrosion protection programs increasingly incorporate digital tools—corrosion monitoring networks, predictive analytics, and digital twins—to optimize protection system performance and maintenance scheduling.
• Training and skills: The quality of corrosion protection depends heavily on the skills of the personnel who apply and inspect linings. Investment in training and certification programs is essential but often underfunded.

Study Insights and Implications

This paper, though published in 1989, provides a valuable historical perspective on the evolution of corrosion protection practices in power plant water treatment systems. The fundamental engineering principles it describes—material-medium compatibility, proper construction techniques, and thorough quality inspection—remain the cornerstone of effective corrosion protection design.

For contemporary engineers, the paper serves as a reminder that corrosion protection is not merely a materials selection exercise but a comprehensive engineering discipline encompassing design, materials, construction, inspection, and maintenance. The transition from traditional mortar linings to modern advanced coatings and material upgrades reflects the broader evolution of the industry, but the underlying engineering philosophy remains constant: protect the asset by understanding the degradation mechanism, selecting appropriate countermeasures, ensuring proper implementation, and maintaining throughout the service life.

The paper also highlights an important but often overlooked aspect of corrosion protection: the interface between design and construction. A corrosion protection system designed on paper is only as good as its execution in the field. Engineers must therefore maintain close involvement throughout the construction phase, providing technical oversight and quality verification to ensure that the as-built protection system matches the design intent. This principle, articulated clearly in this early work, continues to guide best practices in pipeline and equipment corrosion protection today.