RH Snorkel Overview: Up-Leg & Down-Leg Immersion Tubes for RH Degassing
The snorkel is the critical consumable component that directly contacts circulating molten steel in RH vacuum degassing — twice, once ascending through the up-leg under argon lift-gas injection, and once descending through the down-leg at full circulation velocity. Its construction relies on three integrated sections working in harmony, rather than a single continuous pour: an erosion-resistant magnesia-chrome brick body, a rigid mid-wall steel structural can that ensures handling and installation integrity, and an independently cast corundum-grade castable nose section engineered to withstand extreme deep-immersion thermal gradients. We engineer each snorkel assembly against your precise vessel geometry, circulation rate, and lift-gas flow rates — eliminating generic catalog sizing and premature operational failure.
Why Up-Leg and Down-Leg Wear on Different Schedules
Up-Leg: Gas-Erosion Dominant
Argon lift gas injected through tuyeres at the base of the up-leg reduces apparent liquid density to drive vacuum circulation. That gas injection band and the high-turbulence multiphase column above it face severe gas-side shear erosion and rapid bubble collapse, making the injection zone the primary failure bottleneck.
Down-Leg: Velocity and Slag Contact Dominant
Degassed steel returns through the down-leg at maximum exit velocity, carrying dynamic secondary slag carryover. This wear pattern is governed by kinetic fluid shear and chemical slag dissolution rather than gas impingement, generating a distinctly different wear envelope.
What This Means for Refractory Spares Planning
Treating the up-leg and down-leg as identical interchangeable spare parts overlooks their opposing failure mechanisms. Leading global steelmakers track and manage the two snorkels on independent maintenance cycles, often specifying reinforced refractory grades for the up-leg to balance campaign life.
Snorkel Construction: Three Integrated Functional Sections
Magnesia-Chrome Working Lining (Brick Body)
Direct contact with circulating molten steel, lift gas, and slag carryover occurs along the high-fired brick body. High-purity magnesia-chrome provides essential refractoriness and oxidation-reduction stability, custom-formulated according to your steel cleanliness standards and circulation intensity.
Steel Can (Structural Mid-Wall Shell)
The mid-wall structural steel casing provides vital mechanical rigidity. It allows the heavy segmented refractory assembly to be safely transported, craned, and bolted to the RH bottom shell while maintaining precise geometric tolerances under thermal cycling.
Cast Nose Section (RH Castable) — a Separate Piece, Not a Continuous Pour
The lower tip of the snorkel — subjected to the deepest immersion and sharpest thermal shock gradients — is cast independently as a precast monolithic unit. Keeping the nose section modular enables fast tip refurbishment without scrapping or dismantling the upper brick body.
Supply Scope: Turnkey Assemblies or Standalone Materials
Different meltshops require different supply models depending on in-house maintenance capabilities. We support three flexible procurement formats:
Complete Snorkel Assembly (Turnkey Unit)
Fully integrated magnesia-chrome brick lining, structural steel can, and precast castable nose section delivered as a ready-to-install drop-in assembly, 100% inspected against your vessel drawings.
Corundum-Grade RH Castable — Supplied Separately
High-purity low-cement corundum-spinel castable available in bulk bags for plants that cast and cure their own snorkel nose sections or maintain RH vessel bottom linings in-house.
Magnesia-Chrome RH Gunning Mix (Spray Repair Material) — Supplied Separately
Specialized magnesia-chrome spray repair mix engineered for hot maintenance between heats. Delivers high adhesion and rapid setting to patch localized wear around snorkel throats without taking the vessel off-line.
Snorkel Dimensions — Matched to Your Vessel and Lift-Gas System
Snorkel inner diameter (ID), wall thickness, and immersion length must strictly align with your vessel circulation targets and lift-gas parameters. Off-the-shelf sizing compromises circulation speed and accelerates refractory wash. Our engineers verify all bore and mounting tolerances directly against your plant drawings before casting.
Cross-sectional assembly diagram: magnesia-chrome brick body, mid-wall structural steel can, and modular castable nose tip.
Technical Data Sheets: Snorkel and Related RH Materials (TDS)
Magnesia-Chrome Brick (Snorkel Working Lining, Brick Body)
| Property | Typical Specification |
|---|---|
| MgO Content (%) | ≥ 60 |
| Cr₂O₃ Content (%) | 8 – 18 |
| Fe₂O₃ Content (%) | ≤ 8 |
| Bulk Density (g/cm³) | ≥ 3.10 |
| Apparent Porosity (%) | ≤ 17 |
| Cold Crushing Strength (MPa) | ≥ 50 |
| Refractoriness Under Load, T₀.₆ (°C) | ≥ 1700 |
| Thermal Shock Resistance (1100°C ↔ water) | ≥ 10 cycles |
Corundum Castable (Cast Nose Section / RH Outer Layer)
| Property | Typical Specification |
|---|---|
| Al₂O₃ Content (%) | ≥ 85 |
| SiO₂ Content (%) | ≤ 8 |
| CaO Content (%) | ≤ 2.0 (Ultra-low cement) |
| Bulk Density, 110°C dried (g/cm³) | ≥ 2.95 |
| Bulk Density, 1500°C fired (g/cm³) | ≥ 3.05 |
| Cold Crushing Strength, 110°C (MPa) | ≥ 60 |
| Cold Crushing Strength, 1500°C (MPa) | ≥ 100 |
| Apparent Porosity, 1500°C (%) | ≤ 18 |
| Permanent Linear Change, 1500°C × 3h (%) | ± 0.5 |
| Max Service Temperature (°C) | 1700 |
RH Gunning Mix (Spray Repair Material, Magnesia-Chrome Based)
| Property | Typical Specification |
|---|---|
| MgO Content (%) | ≥ 65 |
| Cr₂O₃ Content (%) | 5 – 10 |
| Bulk Density, cured (g/cm³) | ≥ 2.85 |
| Cold Crushing Strength, 110°C (MPa) | ≥ 15 |
| Setting Time (min) | 5 – 15 (Rapid hot setting) |
| Adhesion to Substrate Lining | Pass (Zero spalling on cycling) |
| Max Service Temperature (°C) | 1650 |
*Reference laboratory data under standard test regimes. Mill test certificates (MTC) and lot-specific inspection reports provided with each dispatch.
Reading Snorkel Wear — What Procurement Should Ask Operations Before Reordering
Even Erosion Along the Circulation Band
Normal hydrodynamic wear profile. Review whether the current brick grade's wear rate per 100 heats is matching expected targets or whether operating circulation rates have increased.
Localized Wear at the Gas Injection Band (Up-Leg Specific)
Points to lift-gas flow anomalies, gas injector nozzle erosion, or excessive argon backpressure, rather than poor brick chemistry. Check the gas delivery circuit before changing brick specs.
Chrome-Oxidation Discoloration / Spinel Buildup
Indicates active reaction between the magnesia-chrome refractory and aggressive FeO/MnO-rich carryover slag under deep vacuum. Signal to review upstream slag cutoff control in the steel ladle.
What a Procurement Spec Should Include — Beyond "Magnesia-Chrome Snorkel"
Key Technical Specification Parameters
Engineering Dimension Inputs:
Standard Quality Review Checkpoints:
- Bore ID and Wall Thickness: Exact up-leg and down-leg internal bore tolerances confirmed against RH circulation models.
- Steel Can Structural Interface: Flange bolt-circle pattern, lift-gas inlet ports, and vessel bottom shell mechanical interlock details.
- Refractory Chemistry Range: Target Cr₂O₃ percentage (8–18%), MgO purity, and bulk density limits rather than generic brand names.
- Raw Material Consistency: Dedicated supply from high-purity dead-burned or fused magnesia sources to guarantee repeatable campaign life across batches.
Frequently Asked Questions: RH Snorkels (FAQ)
What is the difference between an up-leg and down-leg snorkel?
The up-leg carries lift-gas-driven steel upward into the vacuum vessel and experiences maximum wear at the gas injection band; the down-leg discharges degassed molten metal back into the ladle at full velocity and wears primarily from hydrodynamic shear and slag contact.
Why is the cast nose section separate from the brick body instead of one continuous piece?
The nose undergoes the deepest bath immersion and sharpest thermal shock gradients. Casting it as an independent modular piece allows fast tip re-profiling or refurbishment without tearing down or scrapping the entire upper brick body.
Why does the snorkel include a steel can in the middle of the wall?
The steel can provides structural rigidity, enabling the heavy segmented refractory unit to be handled by crane and mounted securely to the vessel shell while resisting mechanical bending during vacuum operation.
Can up-leg and down-leg snorkels use the same magnesia-chrome grade?
Often yes, but because their wear mechanisms differ, high-tonnage meltshops frequently specify a higher Cr₂O₃ fused-grain grade on the up-leg to balance campaign replacement intervals across both legs.
Can we buy RH castable or gunning mix without the full snorkel assembly?
Yes. Both our high-purity corundum castables and magnesia-chrome spray gunning mixes are available as standalone bulk shipments for plants managing their own in-house casting and hot spray repair programs.
Can you match our snorkel to our current supplier's dimensions?
Yes. Submit your vessel drawings or dimensional measurements from a decommissioned snorkel; our engineering team verifies bore ID, wall thickness, and mounting flanges prior to fabrication.
Related Secondary Refining Refractory Solutions
- RH Vacuum Degasser Refractory Solutions — Complete zoned lining design for RH vessel dome, throat, and lower chamber.
- AOD & VOD Refractory Supplier — Magnesia-chrome and magnesia-calcium brick linings for stainless steel refining.
- Ladle Furnace (LF) Refractory Solutions — Slag line MgO-C brick and delta roof high-alumina castables.
- Steel Ladle Refractory Solutions — Working lining, safety lining, porous purging plugs, and slide gate systems.
- Ladle Well Block Supplier — Pre-cast nozzle seat blocks in MgO-C, Mg-Cr, and corundum formulations.
- Complete Steel Plant Refractory Solutions — Integrated refractory engineering and consumable supply across modern meltshops.
Request Snorkel Specifications & Engineering RFQ
Send your RH vessel capacity, lift-gas flow rate, and current snorkel dimensions or wear pattern — our engineering team confirms grade, construction, and supply format (full assembly or standalone materials) within 24–48 hours.
Direct Engineering Email: sales@ykchanshine.com | Plant Line: +86-139-9807-2158