Carbon Raschig Ring

Carbon Raschig Ring

Carbon Raschig ring is a hollow-cylinder tower packing made from impervious graphite — colloidal graphite bonded with phenolic resin and heat-treated — for the most corrosive duties of all. Its stand-out property is that it resists hydrofluoric acid, up to about 48 percent, along with nitric, sulphuric and hydrochloric acids, strong alkalis, salts and organic solvents, a span of chemistry that would attack ceramic, metal or ordinary plastic. It also conducts heat well, far better than ceramic or plastic, so it shrugs off thermal shock, and it runs to about 200°C. The trade-offs are that it is dearer than ceramic and, like all carbon, brittle. It is the packing for hydrofluoric and mixed-acid service. We make it in a range of sizes.

Impervious graphite (carbon) — resists nearly every corrosive chemical.
Handles hydrofluoric acid to about 48 percent, where ceramic, metal and plastic fail.
High thermal conductivity and low expansion — strong resistance to thermal shock.
Continuous service to about 200°C, with excellent liquid wetting for good mass transfer.
The choice for HF, hot HCl and mixed-acid towers, acidic gas absorption and desulphurisation.

Technial Parameters

Size (mm)	Specific surface area (m²/m³, approx.)	Void fraction (approx.)
25	≈190	≈60%
38	≈150	≈62%
50	≈120	≈64%
76	≈75	≈66%

Figures are typical; graphite walls are relatively thick, so void is moderate. Exact values depend on grade and wall thickness.

Property	Value
Product Type	Carbon random packing (Raschig ring)
Material	Impervious graphite / carbon (graphite powder + phenolic resin, heat-treated)
Standard Sizes	25, 38, 50, 76 mm (custom available)
Colour	Dark grey / black
Shape	Plain hollow cylinder, height ≈ diameter
Max Service Temperature	About 200 °C (resin-bonded impervious grade)
Chemical Resistance	HF (to ~48%), HCl, H2SO4, HNO3, NaOH/KOH, salts, organic solvents
Thermal	High thermal conductivity, low thermal expansion, strong thermal-shock resistance
Strengths	Uniquely resists HF and mixed acids; heat-conducting; excellent wetting and mass transfer
Limitations	Brittle; dearer than ceramic; oxidises slowly in hot air above its rating
Applications	HF and HCl towers, sulphuric-acid units, acidic-gas absorption / desorption, desulphurisation
Trademark	RONGJIAN
Origin	China
HS Code	8419909000
Transport Package	Carton box / ton bag / steel drum

FAQs

What is a carbon Raschig ring used for?

Carbon Raschig ring is used where the chemistry is too aggressive for other packings. Its home ground is hydrofluoric acid service and hot or mixed acids — sulphuric, hydrochloric, nitric — in gas absorption, acidic-gas desorption, scrubbing and desulphurisation towers, and in fertiliser, petrochemical and reforming plants. It appears in propane strippers, acid-gas absorbers, and the purification, absorption, condensation and distillation of strongly corrosive streams. Because graphite conducts heat and resists thermal shock, it also suits duties where the temperature swings or heat has to be carried away. Where ceramic would be eaten by HF, metal would corrode, and plastic would soften, the carbon Raschig ring keeps working.

What is a carbon Raschig ring made of, and what makes it special?

A carbon Raschig ring is made from graphite: fine graphite powder bonded with phenolic resin, pressed to shape and heat-treated, then, in the impervious grade, sealed so liquids and gases cannot soak in. Two things make it special. First, its chemical reach — graphite resists practically everything, most notably hydrofluoric acid, which is the one common acid that destroys ceramic packing, so carbon covers the gap ceramic cannot. Second, it conducts heat, many times better than ceramic or plastic, which means it barely expands with temperature and stands up to sudden thermal shock instead of cracking. It also wets well with almost any liquid, giving efficient mass transfer. In short, it combines near-universal corrosion resistance with heat-conducting toughness.

What chemicals and temperatures can a carbon Raschig ring handle?

On chemistry, a carbon Raschig ring resists hydrofluoric acid up to around 48 percent, along with sulphuric, nitric and hydrochloric acids, sodium and potassium hydroxide, most salts, and organic solvents — a range matched only by the fluoroplastics. On temperature, the impervious resin-bonded grade runs continuously to about 200 degrees; graphite itself is stable far higher, but the binder sets the working limit, and in hot air carbon slowly oxidises, so very hot oxidising service needs care. Its high thermal conductivity and low expansion give it excellent resistance to thermal shock, unlike brittle ceramic. For hydrofluoric, mixed-acid or thermally demanding corrosive duty, few materials match it.

When is carbon worth choosing over ceramic, metal or plastic?

Carbon is the specialist, chosen when the other three materials fall short. Reach for it above all when hydrofluoric acid is present, since ceramic is attacked by HF, or when hot hydrochloric and mixed acids would corrode stainless steel and force an expensive alloy instead. It also wins where thermal shock or heat conduction matters, because it does not crack like ceramic. Against that, it costs more than ceramic and is more brittle than metal, so for ordinary acid duty ceramic is cheaper, for high pressure and efficiency metal is stronger, and for cool corrosive service plastic is lighter and cheaper still. When the duty is genuinely HF or mixed-acid, though, carbon is often the only sensible choice. Tell us the acids and the temperature and we will confirm the fit.

The Raschig ring is the simplest packing shape — a plain hollow cylinder with no cut openings — and made in carbon it becomes a specialist for the harshest chemistry. The material is impervious graphite: graphite powder bound with phenolic resin, formed and fired, then sealed against liquids and gases. Unlike the more familiar packing materials, graphite is chosen not for cost or capacity but for two properties they cannot match. It resists almost every corrosive chemical, hydrofluoric acid included, and it conducts heat, so it withstands thermal shock rather than cracking under it. It also wets readily with any liquid, which keeps mass transfer high. Its limits are that it is brittle, like ceramic, and costs more, and that in hot air it will slowly oxidise.

Its case is clearest in the duties that defeat the other materials:

The challenge	Carbon / graphite	The usual alternative
Hydrofluoric acid (to ~48%)	Resists it	Ceramic is attacked
Hot HCl and mixed acids	Resists, no special alloy	Stainless steel corrodes
Thermal shock	Conducts heat, low expansion — resists	Ceramic cracks
Continuous heat	To about 200°C	Most plastics stop lower

Read together, these mark out carbon's niche: hydrofluoric-acid towers, hot hydrochloric and sulphuric acid units, acidic-gas absorption and desulphurisation, propane strippers, and the distillation and scrubbing of strongly corrosive streams. It is the packing that replaces exotic metal and defeated ceramic in the most punishing acid service. For everyday acid duty, ceramic stays cheaper; for high pressure or top efficiency, metal is stronger; for cool corrosive scrubbing, plastic is lighter and less costly. But when hydrofluoric acid, mixed acids or severe thermal shock are in play, the carbon Raschig ring is in a class of its own. Tell us the chemistry and the temperature and we will size it for you.