H334008 MFT CATEGORY:
Classification
Center Director, Machinery C.E.E.
Port of Charleston
U.S. Customs and Border Protection
200 East Bay Street
Charleston, S.C. 29401
ATTN: Jodie Basmajian, Supervisory Import Specialist; Thomas Trimeloni, Import Specialist
Re: Request for Internal Advice; Classification of Ceramic Filters for Hot Gas Filtration
Dear Center Director:
The following is our decision on a request for internal advice, which was filed on July 5,
2023, on behalf of Ceramic Filter Alliance, LLC (requestor). The request pertains to the
classification under the Harmonized Tariff Schedule of the United States (HTSUS) by U.S.
Customs and Border Protection (CBP) of certain ceramic filters for hot gas filtration. In reaching
the determination below, CBP has considered information submitted with the request and
provided following a virtual conference between the requestor and CBP held on March 5, 2024.
Ceramic Filter Alliance, LLC, requested that certain information submitted in connection
with this internal advice be treated as confidential. Inasmuch as this request conforms to the
requirements of 19 C.F.R. 177.2(b)(7), the importer's request for confidentiality is approved. The
information pertaining to aspects of the ceramic filters' manufacturing process and all
attachments to the internal advice request forwarded to our office will be withheld from
published versions of this decision.
FACTS:
The merchandise under consideration are ceramic filters for hot gas filtration. The subject
ceramic filters are the Cerafil XS and Cerafil TopKat (TK) models, both imported from China.
Certain industrial processes, including cement and glass manufacturing, can emit hot waste flue
gases carrying harmful pollutants including dust and other particulate matter, volatile organic
compounds (VOCs), dioxins, sulfur oxides, and nitrogen oxides. The purpose of the Cerafil XS
and Cerafil TK is to filter out these pollutants under high temperatures.
The Cerafil XS filter is composed of aluminosilicate fibers — measuring 49% alumina
and silica by weight — as well as organic and inorganic binders. The fibers on the filter
measure about 10 microns in diameter with varying lengths, and they give the filter a fibrous
appearance. The filter is shaped into cylindrical "candles" with closed, hemispherical end caps on
one side and a flange on the other. The flange allows the candles to be mounted in an array
within the flue housing. The filter is non-combustible, has a high thermal conductivity, and is
suitable for use up to 9000 C. The Cerafil TK model is identical to the Cerafil XS, with the
exception that a special catalyst is applied to the candles. This catalyst chemically converts
harmful pollutants that pass through the filter into safer alternatives — for example, nitrogen
oxides (NOx) into nitrogen gas (N2). In the case of nitrogen oxides, as the gases pass through the
TK filter, the oxide component chemically binds to the catalyst-coated ceramic fibers and is left
behind, thereby "freeing" the safer nitrogen components. The type of catalyst that gets applied to
the TK fibers, and consequently the chemical reaction that occurs, may differ depending on the
TK's end use.
The Cerafil XS and Cerafil TK are placed in the exhaust gas stream between the emission
source and the stack, which allows for large volumetric flow rates. The filters are mounted in a
"candle" array within the flue housing and are individually called "candles."
The requestor's submission includes information from its website describing the
application of the filters. Among these applications is the ability to "provide virtually 100%
reduction of particulate and dust in hot temperature applications" in "hot gas [and] syngas
filtration systems." I The website continues to advertise that "[flor many of today's newer
solutions, including carbon capture [and] storage (CCS) and syngas, ceramic filters can provide
the highest levels of PM [particulate matter] reduction to minimize any downstream equipment
issues. "2
ISSUES:
First, whether the Cerafil XS is classified under heading 6806, HTSUS, which provides
for "slag wool, rock wool and similar mineral wools", or under heading 8421, HTSUS, which
provides for "filtering or purifying machinery and apparatus, for liquids or gases."
Second, whether the Cerafil TopKat is properly described as "dust collection and air
purification equipment" under statistical reporting number 8421.39.0115 of the HTSUS
Annotated (HTSUSA) or as "other" under statistical reporting number 8421.39.0130, HTSUSA.
1
See Applications, CERAMIC FILTER ALLIANCE, https://ceramicalliance.com/applications/ (last visited
March 12,
2024). Here, "syngas" or "synthesis gas" is a mixture of carbon monoxide and hydrogen that is produced from
"gasification." See generally CHRISTOPHER HIGMAN & MAARTEN VAN DE BURGT, GASIFICATION 1 (2d.
ed. 2008) (defining "gasification" as "the conversion of any carbonaceous fuel to a gaseous product with a useable
heating value").
2
Applications, supra note 1. See also Particulate Removal, NAT'L ENERGY TECH. LAB' Y,
https://netl.doe.gov/research/coal/energy-systems/gasification/gasifipedia/particulate-removal (last visited March 12,
2024).
2
LAW AND ANALYSIS:
Classification under the HTSUS is in accordance with the General Rules of Interpretation
(GRIs). GRI 1 provides that the classification of goods will be determined according to the terms
of the headings of the tariff schedule and any relative section or chapter notes. In the event that
the goods cannot be classified solely on the basis of GRI 1, and if the headings and legal notes do
not otherwise require, the remaining GRIS 2 through 6 will then be applied in order.
GRI 3(a) states that "the heading which provides the most specific description shall be
preferred to headings providing a more general description." It further states that when two or
more headings each refer to part only of the materials or substances contained in mixed or
composite goods, those headings are to be regarded as equally specific in relation to those goods,
even if one of them gives a more complete or precise description of the goods. GRI 3(b) states, in
pertinent part, that goods put up in sets for retail sale that cannot be classified by reference to
GRI 3(a) are to be classified as if they consisted of the component that gives them their essential
character. GRI 3(c) states that when goods cannot be classified by reference to GRIS 3(a) or 3(b),
they are to be classified in the heading that occurs last in numerical order among the competing
headings which equally merit consideration.
The Harmonized Commodity Description and Coding System Explanatory Notes
(ENS) constitute the official interpretation of the Harmonized System at the international level.
While neither legally binding nor dispositive, the ENS provide a commentary on the scope of
each heading of the HTSUS and are generally indicative of the proper interpretation of these
headings.3
We discuss each model of ceramic filter in turn.
1. Classification of the Cerafil XS
The HTSUS headings under consideration for the Cerafil XS are as follows:
6806 Slag wool, rock wool and similar mineral wools; exfoliated
vermiculite, expanded clays, foamed slag and similar expanded
mineral materials; mixtures and articles of heat-insulating,
soundinsulating or sound-absorbing mineral materials, other than
those of heading 6811 or 6812, or of chapter 69:
8421 Centrifuges, including centrifugal dryers; filtering or purifying
machinery and apparatus, for liquids or gases; parts thereof:
Note I(a) to Chapter 84, HTSUS, states that the chapter does not cover "[m]illstones,
grindstones or other articles of chapter 68." Therefore, if the subject Cerafil XS is classifiable
under Chapter 68, HTSUS, it cannot be classified under Chapter 84, HTSUS.
3
see Treasury Decision (T.D.) 89-80, 54 Fed. Reg. 35127, 35127-28 (Aug. 23, 1989).
The terms of heading 6806, HTSUS, provide for, inter alia, "[s]lag wool, rock wool and
similar mineral wools" (emphasis added). The relevant text of the heading limits its scope to
mineral wools that are "similar" to the preceding articles — namely "slag wool" and "rock wool."
3
Therefore, the subject articles must be "similar" to slag wool and rock wool to be classified under
heading 6806, HTSUS, and consequently excluded from Chapter 84, HTSUS.
The EN to Chapter 68, HTSUS, provides in part:
This Chapter covers:
(A) Various products of Chapter 25 worked to a degree beyond that permitted by Note 1
to that Chapter.
(B) The products excluded from Chapter 25 by Note 2 (f) to that Chapter.
(C) Certain goods made from mineral materials of Section V.
(D) Goods made from certain of the materials of Chapter 28 (e.g., the artificial
abrasives).
Some of the goods in category (C) or (D) may be agglomerated by means ofbinders,
contain fillers, be reinforced, or in the case of products such as abrasives or mica be
put up on a backing or support of textile material, paper, paperboard or other
materials.
Most of these products and finished articles are obtained by operations (e.g.,
shaping, moulding), which alter the form rather than the nature of the constituent
material. [emphasis added]
The EN to heading 6806, HTSUS, contains some guidance on what may constitute "similar"
mineral wool, including in pertinent part:
Slag wool and rock wool (e.g., of granite, basalt, limestone or dolomite) are
obtained by melting one or more of these constituents and converting a stream of
the resulting liquid into fibres, usually by centrifugal action and stream or air blast.
This heading also includes a class of "alumino-silicates" known as "ceramic fibres".
They are formed by fusing a blend of alumina and silica, in varying proportions,
sometimes with the addition of small amounts of other oxides such as zirconia,
chromia or boric oxide, and by blowing or extruding the melt into a mass of fibres.
The mineral wools of this heading, like the glass wool of heading 70.19, have a flocculent
or fibrous appearance. [. . . ]
All the above materials are incombustible and excellent heat-insulating, soundinsulating,
or sound-absorbing products.
Based on the Cerafil XS's composition and properties, we find that it meets the terms of
"similar mineral wool" under heading 6806, HTSUS. The composition of the Cerafil XS shares
similarities with goods mentioned in the ENS to Chapter 68 and heading 6806, HTSUS. The
Cerafil XS specifically includes organic and inorganic binders, as the EN to Chapter 68, HTSUS,
puts forward. The subject merchandise also consists of "a blend of alumina and silica, in varying
proportions" as provided by the EN to heading 6806, HTSUS, specifically 49% alumina and
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silica by weight. Further tracking the EN to heading 6806, HTSUS, the ceramic fibers give the
Cerafil XS a "flocculent appearance" and are non-combustible due to their high thermal
conductivity. Forming a Cerafil XS filter may not involve "fusing" this aluminosilicate blend; nor
is the filter blown or extruded during production. But the EN to Chapter 68, HTSUS, does grant
that "[m]ost of these products and finished articles are obtained by operations (e.g., shaping,
moulding), which alter the form rather than the nature of the constituent material." In this case,
the inherent characteristics of the Cerafil XS's ceramic fibers do not change despite undergoing
shaping operations. These operations, therefore, change the form of the fibers into a wet-formed
element "rather than the nature of the constituent material."
Given these characteristics, the subject Cerafil XS is classifiable as "similar mineral
wool" under heading 6806, HTSUS, by application of GRI 1.
11. Classification of the Cerafil TopKat (TK)
We cannot say the same for the subject Cerafil TopKat (TK), however. "Similar mineral
wool" is an eo nomine provision because it describes an article by a specific name (i.e., "mineral
wool"). In CamelBak Products, LLC v. United States, the Court of Appeals for the Federal
Circuit explained how to determine whether an article falls under an eo nomine provision by
application of GRI 1 :
With regard to assessing an imported article pursuant to GRI 1, we consider a
HTSUS heading or subheading an eo nomine provision when it describes an article
by a specific name. Absent limitation or contrary legislative intent, an eo nomine
provision includes all forms of the named article, even improved forms. [. . . ]
However, [. . . ] when an article is in character or function something other than as
described by a specific statutory provision—either more limited or more
diversified—and the difference is significant, it is not properly classified within an
eo nomine provision. In order to determine whether the subject article is
classifiable within an eo nomine provision, we look to whether the subject article
is merely an improvement over or whether it is, instead, a change in identity of the
article described by the statute. [. . . ] The criterion is whether the item possesses
features substantially in excess of those within the common meaning of the
term.1Here, the TopKat possesses a feature substantially in excess of that within
the common meaning of the term "mineral wool," namely a special catalyst that
gets applied to the element. As we explained above, this catalyst chemically
converts certain harmful pollutants that pass through the filter into safer
alternatives. That function is not one described by the ENS to Chapter 68 and
heading 6806, HTSUS, suggesting that the subject TopKat is significantly different
from the rock wool and slag wool provided in the heading. The catalytic
conversion of gases, as exhibited by the TopKat, is simply not a function that
comports with the common meaning of "mineral wool," much less mineral wool
"similar" to rock wool or slag wool. Because this catalyst substantially exceeds the
characteristics of "mineral wool," the Cerafil TopKat cannot be classified under
Chapter 68, HTSUS.
The HTSUSA provisions under consideration for the Cerafil TopKat are as follows:
1
CamelBak Prods., LLC v. United States, 649 F.3d 1361, 1364—65 (Fed. Cir. 2011) (quotation marks and internal
citations omitted).
5
8421 Centrifuges, including centrifugal dryers; filtering or purifying
machinery and apparatus, for liquids or gases; parts thereof:
Filtering or purifying machinery and apparatus for gases:
8421.39.01 Other
Dust collection and air purification
equipment
8421.39.0115 Other
Other
Industrial gas cleaning equipment
8421.39.0130 Other
There is no dispute that the subject TopKat constitutes "filtering machinery" under
heading 8421, HTSUS, and it is clearly designed for filtering "gases" in accordance with goods
classifiable under subheading 8421.39, HTSUS. 2 The crux of the matter lies in whether the
TopKat meets the terms of "dust collection and air purification equipment" under statistical
reporting number 8421.39.0115, HTSUSA, or if it exhibits alternative functions or characteristics
such that it must be classified as "other" under statistical reporting number 8421.39.0130,
HTSUSA.
On one hand, the subject TopKat clearly exhibits "dust collection" functions described by
statistical reporting number 8421.39.0115, HTSUSA. Like the Cerafil XS, the TopKat consists of
ceramic fibers that measure roughly ten micrometers in diameter and in varying lengths. These
fibers allow for fine particulate matter, including dust, to collect on the fibers, hence the
TopKat constituting "dust collection equipment." On the other hand, the TopKat's ability to
chemically convert harmful pollutants via the applied catalyst is not a function covered by either
of the terms "dust collection" or "air purification."
To constitute "air purification," the TopKat's operations must involve "purifying" (i.e.,
"remov[ing] impurities or contaminants" from) "air." 3 For purposes of the subject request, "air"
is "the invisible gaseous substance which immediately surrounds the earth, is breathed by all
terrestrial animals, and is now recognized as a mixture of oxygen and nitrogen, with smaller
amounts of other substances." 4 Therefore, "air purification," as described by statistical reporting
number 8421.39.0115, HTSUSA, must be the removal of impurities or contaminants from that
breathable mixture of oxygen, nitrogen, and other fragmentary substances.
2
The subject merchandise falls under the "[o]ther" category under subheading 8421.39, HTSUS, because the
superior subheadings 8421.31 and 8421.32, HTSUS, are inapposite. Subheading 8421.31, HTSUS, provides for
"[i]ntake air filters for internal combustion engines," while subheading 8421.32, HTSUS, provides for "[c]atalytic
converters or particulate filters, whether or not combined, for purifying or filtering exhaust gases from internal
combustion engines."
3
See Purify, v. meanings, etymology and more, OXFORD ENG. DICTIONARY,
https://www.oed.com/dictionary/purify_v?tab=meaning_and_use#27544640 (last modified Mar. 2024).
4
See Air, n. l meanings, etymology and more, OXFORD ENG. DICTIONARY, https://www.oed.com/dictionary/air nl
?tab=meaning_and_use#7945046 (last modified Mar. 2024). See also The Atmosphere, NAT'L OCEANIC &
ATMOSPHERIC ADMIN., https://www.noaa.gov/jetstream/atmosphere (last modified July 28, 2023) (producing a chart
of the chemical makeup of the atmosphere, excluding water vapor).
6
Although the TopKat does filter out harmful pollutants through the special catalyst, this
method as applied here does not constitute "air purification" under the terms of statistical
reporting number 8421.39.0115, HTSUSA. In the paradigmatic case, the input nitrogen oxide is
not "air," and neither is the output nitrogen gas. Both the input nitrogen oxide and air contain
nitrogen, but they are not the same substance. Similarly, the output nitrogen gas may be present
in the mixture known as air, but just as a component element is not necessarily the same as the
whole, nitrogen gas alone is not the same as air. Thus, even if the subject TopKat does "remove
contaminants" in the form of harmful gases, since neither the inputs nor outputs constitute "air,"
the catalyst's conversion of pollutants into safer alternatives is significantly different from the
purification of "air." As far as the competing provisions are concerned, that conversion function
must be encompassed by the "other" provision.
We therefore find that the subject TopKat exhibits functions classifiable under both of the
relevant provisions — namely the "dust collection" function under statistical reporting number
8421.39.0115, HTSUSA, and the conversion of and removal of pollutants from substances other
than air, or "other," under statistical reporting number 8421.39.0130, HTSUSA. Since both
provisions describe the subject TopKat, we must apply GRI 3.
The TopKat cannot be classified by application of GRI 3(a). Under that rule, two or more
provisions are equally specific if they "each refer to part only of the materials or substances
contained in mixed or composite goods." Even though statistical reporting number
8421.39.0130, HTSUSA, provides for "other," we noted above that this provision includes the
chemical conversion function exhibited by the catalyst. Therefore, in this matter, "dust collection
equipment" and "other" each refer to part of the TopKat's functions and are thus equally specific
in relation to each other. We further note that the TopKat cannot be classified by application of
GRI 3(b) as there is no indication that either function — "dust collection" or chemical conversion
plays a more prominent role in relation to the use of the goods. Since the TopKat cannot be
classified by application of GRI 3(a) or 3(b), we turn to GRI 3(c), which instructs us to classify
the good under the provision which occurs last in numerical order. Here, that provision is
statistical reporting number 8421.39.0130, HTSUSA.
We hold that the subject Cerafil TopKat (TK) is classified under subheading 8421.39.01,
HTSUS, more specifically under statistical reporting number 8421.39.0130, HTSUSA, as
"other", by application of GIRs 1, 3(c), and 6.
HOLDING:
By application of GRIS 1 and 6, the subject Cerafil XS is classified under heading
6806, HTSUS, specifically subheading 6806.90.OO, HTSUS, which provides for, "Slag wool,
rock wool and similar mineral wools; exfoliated vermiculite, expanded clays, foamed slag and
similar expanded mineral materials; mixtures and articles of heat-insulating, sound-insulating or
sound-absorbing mineral materials, other than those of heading 6811 or 6812, or of chapter 69:
Other." The general column one rate of duty is free.
By application of GRIS 1, 3(c), and 6, the subject Cerafil TopKat (TK) is classified under
heading 8421, HTSUS, specifically subheading 8421.39.01, HTSUS, which provides for,
"Centrifuges, including centrifugal dryers; filtering or purifying machinery and apparatus, for
liquids or gases; parts thereof: Filtering or purifying machinery and apparatus for gases: Other."
The general column one rate of duty is free.
7
Pursuant to U.S. Note 20 to Subchapter Ill, Chapter 99, HTSUS, products of China
classified under subheading 6806.90.00, HTSUS, unless specifically excluded, are subject to an
additional 25 percent ad valorem rate of duty. At the time of importation, you must report the
Chapter 99 subheading, i.e., 9903.88.03, in addition to subheading 6806.90.00, HTSUS, listed
above.
Pursuant to U.S. Note 20 to Subchapter Ill, Chapter 99, HTSUS, products of China
classified under subheading 8421.39.01, HTSUS, unless specifically excluded, are subject to an
additional 25 percent ad valorem rate of duty. At the time of importation, you must report the
Chapter 99 subheading, i.e., 9903.88.01, in addition to subheading 8421.39.01, HTSUS, listed
above.
You are directed to mail this decision to the Internal Advice applicant no later than 60
days from the date of this letter. On that date, the Office of Trade, Regulations and Rulings, will
make the public version of the decision available to CBP personnel and to the public at
https://www.cbp.gov by means of the Freedom of Information Act and by other methods of public
distribution.
Sincerely,
Yuliya A. Gulis, Director
Commercial and Trade Facilitation Division
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