Anchor Systems in Castable or Brick Lining in Different Vessels

 

 

 

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Introduction

Anchoring plays a crucial role in the stability and longevity of refractory linings in industrial vessels. This post explores different types of anchor systems, their materials, layout, welding techniques, and the effects of corrosion, embrittlement, and insulation on anchorage.

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1. Anchor Types

Metallic – Fixed

• Standard REVA-W anchoring
• Other types upon customer agreement

Metallic – Flexible

• Metallic wave anchoring (REVA-W)
• RHA anchors bridge insulation
• Preassembly using Lasche

Ceramic Anchors

• Prefabricated components, including concrete anchoring and expansion joints

Special Anchors

• Used for brick anchoring in vertical walls, bullnose applications, etc.

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2. Anchor Materials and Selection Criteria

When selecting anchor materials, consider:

• Expected thermal and mechanical loads
• Chemical exposure
• Professional installation and welding quality

Material Temperature Resistance:

Anchor Cap Color Codes for Alloy Identification:

• White – 1.4301
• Red – 1.4828
• Brown – 1.4835 / 253MA
• Blue – 1.4837 / 1.4841 / 1.4845
• Green – 1.4876 / 2.4633
• Orange – 2.4856

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3. Anchor Layout & Distance

Roof Anchors

• 90° angle to each other
• Anchor distance:
  • <150mm lining thickness → 200mm (25 pieces/m²)

  • 150mm lining thickness → 250mm (16 pieces/m²)

Wall Anchors

• 90° angle to each other
• Anchor distance:
  • <150mm lining thickness → 200mm (25 pieces/m²)

  • 150mm lining thickness → 250mm (16 pieces/m²)

Zyclon Cone / Bottom Anchors

• 90° angle to each other
• Anchor distance: 330mm (9 pieces/m²)

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4. Welding Electrode Selection

Factors to consider:

• Chemical exposure
• Professional welding techniques (manual electrode, stud/bolt welding)

Material Combinations for Welding Electrodes:

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5. Corrosion in Anchor Systems

Electrochemical Corrosion

Occurs due to reactions with surrounding substances, leading to material degradation.

High-Temperature Corrosion (Scaling)

• Caused by molten salts, gases, and electrolytic reactions.

Types of Corrosion:

• Surface corrosion: Can increase volume and create internal tension in refractory linings.
• Internal corrosion: Weakens metal structure, reducing creep rupture strength.
• Stress corrosion: Occurs at grain boundaries due to chemical exposure and mechanical stress.
• Chemical corrosion (Laboratory Tests):
  • KCl (800°C, oxidizing)
  • K₂SO₄ (1100°C, oxidizing)
  • K₂SO₄ (1100°C, reducing)

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6. Embrittlement of Anchor Materials

Factors Causing Embrittlement:

• Chi-Phase (475°C Embrittlement):
  • Forms at 400-550°C in steels with >15% chromium.
• Sigma-Phase Embrittlement:
  • Occurs at 600-900°C, reducing chromium and molybdenum in metal structure.
  • Cold deformation accelerates sigma-phase formation.
  • Nitrogen and carbon can reduce sigma-phase formation.

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7. Effect of External Insulation on Anchorage

• Best practice: Maximum internal insulation to prevent external corrosion.
• Case study:
  • Märker Zement – Mascoat Usage (July 2021): Applied to calciner falling ducts.
• Risks of external insulation:
  • Clinker dust buildup
  • Insulation deterioration and failure

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Conclusion

Proper selection of anchor types, materials, layout, welding, and insulation methods ensures the longevity and performance of refractory linings in industrial vessels. Considering factors like temperature, corrosion, and embrittlement can help optimize anchor system efficiency.

 

 

 

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