CLA-2-84:OT:RR:NC:N1:104
Kevin Doucette
C.H. Robinson International, Inc.
14701 Charlson Rd
Eden Prairie, MN 55347
RE: The tariff classification of anaerobic digester reactors from Austria
Dear Mr. Doucette:
In your letter dated December 3, 2025, you requested a tariff classification ruling on behalf of your client,
CST Industries, Inc.
The products in question are five types of anaerobic digester reactors, referred to as RNG1 Tank Farm AD
Reactors (reactors). These reactors will be imported unassembled for installation into a biogas production
plant in Kentucky, with each reactor imported separately in a single entry under multiple conveyances.
The five reactor types are the primary reactor, secondary reactor, stillage reactor, filtrate reactor, and feed
reactor. In their condition as imported, the reactors share certain common components and features. All are
above-ground units with double-contained steel vessels (tanks). Each reactor includes a double-membrane
gas holder roof, air support blowers, mixing apparatus, pressure release valves, methane gas warning system,
safety valves, operating controls, viewing ports, inlet nozzles, central support column, and lightening
protection. The five reactor types are designed to carry out specific steps in the anaerobic digestion process,
as follows.
The feed reactor is the first stage of the anaerobic digestion process and is smaller in size than the other
reactors. The feed reactor receives organic digestate, grinds or macerates the material to increase the surface
area and homogenizes it into a slurry that is heated, beginning anaerobic digestion hydrolysis process. From
the feed reactor, the stillage is pumped through sealed, above-ground steel pipes to the other reactors, where
it is broken down to produce renewable natural gas, renewable carbon dioxide, and sustainable soil
conditioner products. The stillage reactor’s tank is highly specific to distillery stillage residue from ethanol or
alcohol distillation. This vessel is the second stage of the anaerobic digestion process where blending and
dosing to neutralize the pH occurs. Its function is to ensure the active digestion stillage is fed into the primary
reactors slowly and consistently to keep the anerobic digestion process progressing in the acid phase. The
filtrate reactor is the last step in completing anaerobic digestion as it receives the digestate from the
secondary digester reactor and separates the liquid centrate from the dewatered solids and returns the liquid
to the headworks, thus stopping the anaerobic digestion process.
The applicable subheading for the anaerobic digester reactors, each imported unassembled under a single
entry and otherwise in accordance with 19 CFR 141.58 (as applicable), will be 8479.89.9599, which provides
for “Machines and mechanical appliances having individual functions, not specified or included elsewhere in
this chapter; parts thereof: Other machines and mechanical appliances: Other: Other: Other.” The general rate
of duty will be 2.5% ad valorem.
The duties cited above are current as of this ruling’s issuance. Duty rates are provided for your convenience
and are subject to change. The text of the most recent HTSUS and the accompanying duty rates are provided
at https://hts.usitc.gov/.
This ruling does not address the applicability of any additional duties, taxes, fees, exactions and/or other
charges, which may apply to the goods discussed herein. This includes, but is not limited to, tariffs and other
duties as provided for in Subchapter III to Chapter 99, HTSUS. Thus, for example, in addition to the
classification stated above, the merchandise covered by this ruling may also need to be reported with either
the Chapter 99 provision under which an additional tariff applies or one of the Chapter 99 provisions
covering exceptions to such tariffs.
For further information to assist with the importation process, please refer to the frequently updated Cargo
Systems Messaging Service (CSMS) messages at
https://www.cbp.gov/trade/automated/cargo-systems-messaging-service and Frequently Asked Questions on
the Trade Remedy/IEEPA page at
https://www.cbp.gov/trade/programs-administration/trade-remedies/IEEPA-FAQ.
The holding set forth above applies only to the specific factual situation and merchandise description as
identified in the ruling request. This position is clearly set forth in Title 19, Code of Federal Regulations
(CFR), Section 177.9(b)(1). This section states that a ruling letter is issued on the assumption that all of the
information furnished in the ruling letter, whether directly, by reference, or by implication, is accurate and
complete in every material respect. In the event that the facts are modified in any way, or if the goods do not
conform to these facts at time of importation, you should bring this to the attention of U.S. Customs and
Border Protection (CBP) and submit a request for a new ruling in accordance with 19 CFR 177.2.
Additionally, we note that the material facts described in the foregoing ruling may be subject to periodic
verification by CBP.
This ruling is being issued under the provisions of Part 177 of the Customs and Border Protection
Regulations (19 C.F.R. 177).
A copy of the ruling or the control number indicated above should be provided with the entry documents
filed at the time this merchandise is imported. If you have any questions regarding the ruling, please contact
National Import Specialist Arthur Purcell at [email protected].
Sincerely,
(for)
Evan Conceicao
Designated Official Performing the Duties of the Division Director
National Commodity Specialist Division