Chapter 6903 — Customs Tariff Headings

Carbon Crucible for Aluminum Die Casting

A large graphite crucible engineered for melting aluminum alloys in die casting operations. It contains more than 50% free carbon by weight and is fired after shaping, qualifying as a refractory ceramic good under this tariff item. Designed to withstand temperatures up to 1400°C in non-ferrous foundry environments.

Carbon Graphite Nozzle for Continuous Casting

A refractory graphite nozzle used in steel continuous casting to regulate molten metal flow. Composed of more than 50% free carbon by weight and fired at high temperatures, it meets the definition of a refractory ceramic good. Essential for controlling metal flow in industrial steel production.

Graphite Crucible for Metal Melting

A high-density graphite crucible designed for melting precious metals such as gold and silver in foundry operations. It contains over 50% free carbon by weight and is fired after shaping from inorganic non-metallic materials including graphite. Suitable for high-temperature metal processing applications.

Graphite Immersion Heater Tube

A protective graphite sheath tube for immersion heaters used in molten metal baths. Its high free carbon content, exceeding 50% by weight, provides corrosion resistance in aggressive environments. Fired after shaping, it qualifies as a refractory ceramic good under this tariff item.

Graphite Slide Gate Refractory for Steel Ladles

Slide gate plates made from high-carbon graphite for controlling molten steel flow in ladles. They exceed 50% free carbon content and are fired ceramic refractory goods designed for extreme temperatures. Critical components in steelmaking operations for precise flow control.

Graphite Stopper Rod for Molten Metal Pouring

A refractory graphite stopper rod used to control molten steel pouring from ladles. With high free carbon content exceeding 50%, it offers thermal shock resistance after the ceramic firing process. Standard equipment in foundries for precise metal flow regulation.

High-Carbon Graphite Retort for Laboratory Use

A sealed graphite retort vessel for high-temperature chemical reactions and distillation processes. It contains over 50% free carbon and is fired after shaping, meeting Chapter 69 requirements. Used in analytical and research laboratories for demanding thermal applications.

High-Purity Graphite Cupel for Fire Assay

Specialized graphite cupels used in fire assay for precious metal analysis. They contain over 50% free carbon and are fired after shaping for analytical laboratory use. These cupels absorb the lead button during precious metal parting, ensuring accurate results.

Alumina Ceramic Retort for Chemical Processing

Fired alumina retort containing over 80% alumina (Al2O3) by weight, used for high-temperature chemical reactions and distillation processes. This refractory vessel withstands corrosive environments and thermal shock, meeting the criteria for refractory ceramic goods under tariff item 6903.20.00.

Alumina Ceramic Support for Catalyst Bed

High-alumina ceramic support structures containing over 65% alumina (Al2O3) by weight, fired after shaping at temperatures exceeding 800°C. These refractory goods are used in industrial catalyst beds within petrochemical processing, providing structural integrity at elevated temperatures.

Alumina Crucible for Laboratory Use

High-purity alumina crucible containing over 90% alumina (Al2O3) by weight, designed for melting and holding metals or chemicals in laboratory furnaces. Fired after shaping at temperatures exceeding 800°C, it qualifies as a refractory ceramic good under tariff item 6903.20.00.

Alumina-Silica Kiln Furniture Shelf

Refractory kiln furniture shelf made from a 60% alumina-40% silica mixture, used for supporting ware in ceramic kilns. This high-temperature fired ceramic is designed for repeated thermal cycling, qualifying under tariff item 6903.20.00 as a refractory ceramic good.

Alumina Thermocouple Protection Tube

Fired alumina ceramic tube containing 99% alumina (Al2O3), used to protect thermocouples in high-temperature furnaces and kilns. This essential refractory component for temperature measurement in industrial processes falls under tariff item 6903.20.00.

High-Alumina Ceramic Nozzle for Continuous Casting

Refractory nozzle made from an alumina-silica mixture containing over 70% alumina (Al2O3), used in steel continuous casting to control molten metal flow. This fired ceramic construction withstands extreme temperatures and qualifies under tariff item 6903.20.00.

High-Alumina Plug for Steel Ladle

Refractory alumina plug containing 75% alumina (Al2O3), used in steel ladle stopper assemblies for molten metal control. This precision-engineered, high-fired ceramic component qualifies under tariff item 6903.20.00 as a refractory ceramic good.

High-Purity Alumina Ceramic Rod for Kilns

High-purity alumina ceramic rod made from 99.5% alumina (Al2O3), used as support in high-temperature kilns and sintering furnaces. This fired refractory good provides structural support under extreme thermal conditions, meeting the criteria for tariff item 6903.20.00.

Precision Alumina Ceramic Tube for Thermowells

High-precision alumina ceramic tube made from 96% alumina (Al2O3), used for protecting temperature sensors in harsh industrial environments. This refractory fired construction is designed for continuous high-temperature service, qualifying under tariff item 6903.20.00.

Refractory Alumina Slide Gate Plate

High-alumina ceramic plate containing 85% alumina (Al2O3), used in steel ladle slide gate systems to control molten steel flow. This precision-fired refractory component is essential for steelmaking and falls under tariff item 6903.20.00.

Alumina Ceramic Retort

A high-alumina ceramic retort designed for laboratory pyrolysis and gas synthesis reactions at temperatures exceeding 1600°C. This product is a refractory ceramic good, explicitly named in tariff item 6903.90.00, and is fired after shaping to achieve its high-temperature stability.

Alumina Crucible

A high-purity alumina ceramic crucible used for melting metals or chemicals at high temperatures in laboratories and foundries. This refractory ceramic good is designed to withstand extreme thermal and chemical stress, qualifying under tariff item 6903.90.00.

Ceramic Bushing Support

Recrystallized alumina supports holding heating element bushings in high-temperature electric furnaces. These are fired ceramic goods shaped from alumina and fired above 800°C, qualifying as refractory ceramic supports. Supports are explicitly named in heading 69.03, and the non-clay composition places them under this tariff item.

Ceramic Ladle Plunger

A zirconia-graphite ceramic plunger used for stirring molten steel in secondary refining ladles. This refractory ceramic good is high-fired for extreme corrosion resistance and falls under tariff item 6903.90.00 as an 'other' refractory product.

Ceramic Pug Mill Nozzle

A silicon carbide nozzle for high-pressure ceramic pug mills extruding clay products. This refractory nozzle resists abrasive clay slips and is classified under tariff item 6903.90.00 as an 'other' refractory ceramic good.

Ceramic Retort Tube

Fired mullite ceramic retort tube for gas purification processes at elevated temperatures in industrial chemical applications. This is shaped from mullite and fired above 800°C, making it a fired refractory ceramic good. Retort tubes are explicitly named in heading 69.03, and the non-clay composition places it under this tariff item.

Clay Cupel for Assay

A small clay cupel used in precious metal fire assaying to collect beads of gold or silver. It is shaped from refractory clay and fired above 800°C, making it a fired ceramic product. Cupels are explicitly named in heading 69.03 as refractory ceramic goods, and the clay composition places it under this tariff item.

Clay Refractory Crucible

A high-temperature clay crucible used for melting metals in foundries and laboratories. It is shaped from refractory clay and fired above 800°C, qualifying as a fired refractory ceramic good. Crucibles are explicitly named in heading 69.03, and the clay composition places it under this tariff item.

Clay Refractory Kiln Shelf

Heavy-duty clay shelves for supporting pottery in industrial kilns during firing. These are shaped from refractory clay and fired above 800°C, making them fired ceramic supports. Supports are explicitly named in heading 69.03, and the clay composition places them under this tariff item.

Clay Refractory Nozzle

A refractory clay nozzle for steel continuous casting, designed to endure extreme molten metal temperatures. It is fired from special refractory clays above 800°C, making it a fired ceramic good. Nozzles are explicitly named in heading 69.03, and the clay composition places it under this tariff item.

Clay Refractory Pipe

Heavy clay refractory pipes for high-temperature gas transport in furnaces and industrial heating systems. These are shaped from refractory clay and fired above 800°C, qualifying as fired ceramic goods. Pipes are explicitly named in heading 69.03, and the clay composition places them under this tariff item.

Clay Refractory Plug

Refractory clay plugs for sealing furnace ports and ladle openings in high-temperature industrial applications. These are shaped from refractory clay and fired above 800°C, making them fired ceramic goods. Plugs are explicitly named in heading 69.03, and the clay composition places them under this tariff item.

Clay Refractory Rod

Fired clay rods used as stirring tools and supports in high-temperature furnaces and kilns. These are shaped from refractory clay and fired above 800°C, qualifying as fired ceramic goods. Rods are explicitly named in heading 69.03, and the clay composition places them under this tariff item.

Clay Refractory Tube

High-temperature clay tubes for kiln furniture and thermocouple sheaths in industrial furnaces. These are shaped from refractory clay and fired above 800°C, making them fired ceramic goods. Tubes are explicitly named in heading 69.03, and the clay composition places them under this tariff item.

Clay Retort for Laboratory

Traditional clay retorts used in chemical distillation processes at high temperatures in laboratories and industry. These are shaped from refractory clay and fired above 800°C, qualifying as fired ceramic goods. Retorts are explicitly named in heading 69.03, and the clay composition places them under this tariff item.

Clay Slide Gate Refractory

Slide gate plates made of refractory clay for controlling molten steel flow in ladles during continuous casting. These are shaped from refractory clay and fired above 800°C, making them fired ceramic goods. Slide gates are explicitly named in heading 69.03, and the clay composition places them under this tariff item.

Cordierite Kiln Support Shelf

A cordierite ceramic shelf supporting pottery ware during high-temperature kiln firing. This refractory support has low thermal expansion and is classified under tariff item 6903.90.00 as a refractory ceramic good.

Cupel for Fire Assay

A magnesia ceramic cupel used for absorbing lead in precious metal fire assay analysis. This refractory good is specifically named in tariff item 6903.90.00 and is fired to withstand high temperatures.

Cupel Refractory Dish

Bone ash cupel for precious metal assaying in cupellation furnaces, designed to absorb base metals during the assay process. This is fired above 800°C, making it a fired refractory ceramic good. Cupels are explicitly named in heading 69.03, and the non-clay composition places it under this tariff item.

Graphite Crucible with Clay Bond

A clay-bonded graphite crucible for non-ferrous metal melting in jewelry and investment casting. This refractory crucible is made of fired ceramic materials including graphite-carbon composites, qualifying under tariff item 6903.90.00.

Graphite Oxide Nozzle Insert

Carbon-graphite ceramic nozzle insert for non-ferrous metal die casting, designed to withstand high temperatures and thermal shock. This is fired above 800°C, making it a fired refractory ceramic good. Nozzles are explicitly named in heading 69.03, and the graphite-based composition places it under this tariff item.

Kiln Furniture Shelf

Cordierite kiln shelf supporting ceramic ware during bisque and glaze firing cycles in pottery kilns. This is shaped from cordierite and fired above 800°C, making it a fired refractory ceramic good. Supports are explicitly named in heading 69.03, and the non-clay composition places it under this tariff item.

Magnesia Slide Gate Plate

A magnesia-carbon ceramic slide gate plate for controlling molten steel flow in ladle casting. This refractory slide gate is specifically named in tariff item 6903.90.00 and withstands temperatures above 1700°C.

Magnesium Oxide Crucible

A magnesium oxide (MgO) ceramic crucible designed for melting rare earth metals, offering superior corrosion resistance at high temperatures. This fired refractory oxide vessel is shaped at room temperature and then fired, meeting the requirements of Chapter 69. It is classified as an 'other refractory ceramic good' under tariff item 6903.90.00, distinct from basic brick forms.

Muffle Furnace Liner

A high-temperature ceramic muffle liner used to protect furnace chambers from contamination during firing processes. This refractory muffle is fired after shaping from inorganic, non-metallic materials, qualifying under Chapter 69. It is classified as an 'other refractory ceramic good' under tariff item 6903.90.00, as muffles are explicitly listed.

Reaction-Bonded Silicon Carbide Nozzle

A reaction-bonded silicon carbide ceramic nozzle for powder metallurgy spray drying applications. This refractory nozzle survives abrasive high-velocity flows and is classified under tariff item 6903.90.00 as an 'other' refractory good.

Refractory Ceramic Bushing

A zirconia ceramic bushing guiding wires through high-temperature galvanizing furnaces. This refractory tube/rod withstands extreme thermal cycling and is classified under tariff item 6903.90.00.

Refractory Ceramic Furnace Muffle

A high-alumina ceramic muffle protecting furnace heating elements from process atmosphere. This refractory muffle is a named example in tariff item 6903.90.00 and is fired after shaping.

Refractory Ceramic Pipe

A reaction-bonded silicon carbide ceramic pipe used to convey corrosive gases in petrochemical plants. This refractory pipe is fired after shaping from siliceous materials, meeting the Chapter 69 definition of ceramic products. It is classified as an 'other refractory ceramic good' under tariff item 6903.90.00, with pipes explicitly mentioned in the heading.

Refractory Ceramic Rod for Kiln Cars

A high-alumina ceramic leveling rod for kiln car ware supports in sanitaryware firing. This refractory rod is engineered for service above 1400°C and falls under tariff item 6903.90.00.

Refractory Ceramic Slide Gate

High-alumina slide gate plates used to control molten steel flow in ladle casting operations. These fired refractory ceramic goods are shaped at room temperature and fired, meeting Chapter 69 requirements. They are classified under tariff item 6903.90.00, as slide gates are explicitly listed in the heading.

Refractory Ceramic Stopper Rod

An alumina-carbon stopper rod used to control molten steel pour from ladles in steelmaking. This fired composite ceramic rod is shaped at room temperature and fired, qualifying as a refractory ceramic good. It is classified under tariff item 6903.90.00, with rods explicitly mentioned in the heading.

Refractory Kiln Plug

A cordierite ceramic plug used to seal peepholes in pottery kilns, designed to withstand thermal cycling. This fired refractory plug is shaped from clay-silica mixes and fired, meeting Chapter 69 requirements. It is classified under tariff item 6903.90.00, as plugs are explicitly listed in the heading.

Silicon Carbide Thermocouple Tube

A silicon carbide ceramic tube sheathing thermocouples in high-temperature furnaces up to 1600°C. This refractory tube is classified under tariff item 6903.90.00 as a protective sheath for industrial thermal applications.

Silicon Nitride Rod

A dense silicon nitride ceramic rod used for thermocouple supports in molten aluminum holding furnaces. This fired refractory good is made from nitride materials, qualifying under Chapter 69. It is classified under tariff item 6903.90.00, with rods explicitly mentioned, and excludes electrical uses.

Silicon Nitride Thermowell

A silicon nitride ceramic thermowell protecting temperature sensors in petrochemical furnaces. This refractory tube/sheath is fired per Chapter 69 requirements and falls under tariff item 6903.90.00.

Zirconia Nozzle

A zirconium oxide ceramic nozzle used for continuous casting in steel mills, resisting molten metal erosion. This fired refractory ceramic good is shaped at room temperature and fired, meeting Chapter 69 requirements. It is classified under tariff item 6903.90.00, as nozzles are explicitly listed in the heading.