Ceramic Valves for Steel Pickling Lines

Elevated-Temperature Corrosion

Acidic media become increasingly corrosive at elevated operating temperatures, accelerating the deterioration of valve bodies, internal components, and sealing surfaces

Abrasion from Solid Particles

Mill scale and iron-oxide sludge suspended in the acidic liquor cause continuous erosion and abrasive wear of valve internals

Frequent Cycling and Continuous Operation

Valves are subjected to frequent throttling and on/off cycles while operating in continuous counter-current acid circulation

Stringent Sealing Requirements

Acid-mist emissions and the risk of hazardous acid leakage demand reliable shutoff performance and effective fugitive-emission control

Harsh Conditions in Auxiliary Systems

Waste-acid transfer, rinse-water and wastewater handling, and acid-regeneration auxiliary loops face the same severe corrosion and abrasion challenges

Conventional Valve Types and Materials

Butterfly valves are the predominant valve type used in steel-pickling circuits

• Initial solution: Triple-offset metal-seated butterfly valves
• Modified solution: Soft-seated butterfly valves, introduced to address the short service life of metal-seated designs
• Control service: ARCA control valves are used for throttling and flow regulation

Problems with Conventional Valves

Butterfly valves are widely used in both hot-rolled and cold-rolled strip pickling lines. Triple-offset metal-seated butterfly valves were initially installed but proved unreliable. Soft-seated butterfly valves were subsequently introduced; however, their sealing elements are frequently damaged by mill scale and iron-oxide particles, resulting in internal leakage

Replacement Intervals and Service Life

• Domestic butterfly valves: Approximately 7 days to several weeks
• Imported butterfly valves, GEMÜ, EBRO, and Bray: Typically several months; maximum recorded service life approximately 8 months, with none exceeding one year
• Imported ARCA control valves: High acquisition cost but still limited service life, with no significant improvement over imported isolation butterfly valves

Losses Caused by Maintenance Shutdowns

Conventional metal valves suffer rapid chemical attack, pitting corrosion, and erosive wear, resulting in short service life, frequent maintenance, and unplanned pickling-line shutdowns

Industry Pain Points and Improvement Opportunities

Steel pickling commonly uses hydrochloric acid (HCl) or sulfuric acid (H₂SO₄). Stainless-steel pickling generally uses a mixed nitric and hydrofluoric acid solution (HNO₃ + HF)

The process medium is highly corrosive and contains dissolved iron salts together with suspended mill scale and iron-oxide sludge, exposing valves to simultaneous corrosion, erosion, solids buildup, and sealing damage

Excellent Corrosion Resistance

Structural ceramics resist dilute hydrochloric acid (HCl), sulfuric acid (H₂SO₄), and mixed pickling acids, greatly reducing pitting corrosion and media penetration

Superior Abrasion and Erosion Resistance

High-hardness ceramic sealing surfaces withstand erosion and abrasion caused by suspended mill scale and iron-oxide sludge, significantly extending service life compared with stainless-steel and alloy valves

Reliable Sealing Performance

The ceramic-to-ceramic sealing structure maintains tight shutoff after prolonged exposure to abrasive particles, reducing acid leakage and acid-mist emissions

Lower Total Cost of Ownership

Longer service life reduces spare-parts consumption, maintenance frequency, and production shutdowns. Ceramic valves are suitable for pickling-acid circulation, spent pickling liquor transfer, and rinse-water service