Monobloc Stopper Rod for Tundish Flow Control — Including Argon-Blowing Designs

Monobloc stopper rods are pressed as a single piece, and that single fact explains most of their advantage. An assembled stopper has a mechanical joint between body and head; a monobloc does not. Since that joint is the most common site for gas ingress, leaks and breakage, removing it removes the dominant failure mode.

Body and Head Do Different Jobs

A stopper is not a uniform component. The body sits in the steel and needs thermal shock resistance and chemical compatibility. The head takes direct steel impingement, seats against the nozzle, and controls flow — a much harder mechanical duty.

Every XZK grade reflects that: the body runs at 2.30 g/cm³ with cold modulus of rupture ≥5.5 MPa, while the head runs at 2.60–2.70 g/cm³ with MOR ≥7.0 MPa and higher alumina (50–68%). A stopper with a uniform composition is either over-built in the body or under-built at the head.

Argon Blowing: The Clogging Answer

On aluminium-killed and low-carbon steels, alumina deposits inside the bore and restricts flow — the classic clogging problem. Injecting argon through the stopper keeps the bore clear and is usually the first measure worth trying, because it addresses the cause rather than the symptom. If your problem is clogging rather than erosion, specify an argon-blowing design before changing the whole flow-control package.

Preheat-Free: Time and Risk

Preheat-free designs remove the preheat step entirely. The benefit is twofold: shorter turnaround, and elimination of the thermal shock event that preheating (or preheating badly) can cause. On plants with tight tundish turnaround or no dedicated preheat station, this is often worth more than the material cost difference.

Grade Selection

• XZK-ZSLT-A — body 40% Al₂O₃, head 68% Al₂O₃. Highest head alumina.
• XZK-ZSLT-B — body 42%, head 58% (Al₂O₃+MgO). Different head chemistry for specific grades.
• XZK-LS1 — body 42%, head 50% with 10% MgO. Where a magnesia-bearing head performs better.

All grades are rated at 5 thermal shock cycles at 1100 °C water quench with body porosity ≤19%.

Supply

Quoted per set, typically 200–500 pieces minimum, 20–35 days from drawing approval. Custom lengths, head profiles and argon channel configurations are produced to drawing with dimensions confirmed before production. Dimensional inspection reports and batch test data accompany every order.

Where This Grade Sits in the Lining System

Flow-control refractories are consumed on the caster's schedule, so the specification is as much about dimensional repeatability and interchangeability with your existing mechanism as it is about composition. A plate or shroud that fits but varies by a millimetre between lots costs more in breakouts than it saves in unit price.

XZK supplies monobloc stopper rod as one zone of a zoned package rather than as a standalone item: the grades normally zoned alongside it — among them slide gate plate — are documented on the continuous casting functional refractories page, and the vessel-level architecture — where each zone starts and ends, and which mechanism actually limits the campaign — is set out on the tundish flow control page.

The Colakoglu Metalurji slab caster flow control programme reference documents how this class of material performed in full service, with the measured campaign figures rather than datasheet values.