The tariff classification of prefabricated modules from Thailand

N361753
June 16, 2026
CLA-2-84:OT:RR:NC:N1:103
CATEGORY: Classification
TARIFF NO.: 8419.89.9585; 7308.90.9590
Ruby Medrano ExxonMobil Product Solutions Company 22777 Springwoods Village Parkway Spring, TX 77389 RE: The tariff classification of prefabricated modules from Thailand Dear Ms. Medrano: In your letter dated May 22, 2026, you requested a tariff classification ruling. The subject prefabricated modules will be permanently installed at a petrochemical manufacturing facility in Texas. The modules are designed to be stacked vertically on piling foundations to form an ethane cracking furnace, which is described as a thermal processing unit that uses high-temperature cracking to convert ethane feedstock into ethylene and hydrocarbon products. Within the furnace, ethane is mixed with steam at elevated temperatures, a process that breaks molecular bonds and creates lighter hydrocarbon products. A total of ten modules will be imported together in a single shipment. The finished furnace, which will be called Furnace XXIF-01, will be connected to a group of eight existing furnaces at the ethane processing complex. The first module is referred to as the Lower Radiant Section or Firebox. This module forms the lower section of the overall ethane cracking furnace and will consist of a refractory-lined chamber fitted with burners underneath its floor. The function of this module is to generate intense radiant heat, which is sent through vertical radiant tubes to drive the reaction. The radiant tubes are installed after importation and are not part of this request. The second module is referred to as the Upper Radiant Section and is installed directly above the first module. This module functions as an extension of the Lower Radiant Section and consists of a refractory-lined chamber mounted in a structural frame. Its radiant tubes will also be installed after importation and are not part of this request. The third and fourth modules are referred to as Convection Sections. They are stacked one on top of the other and configured to both pre-heat the ethane feed and to superheat very high-pressure steam. Flue gas is used as a heat source to raise and lower the temperature of the feed and steam, transferring thermal energy between

the flue gas, the feed, and the steam. At the time of importation, these two modules will each contain a refractory-lined chamber and structural supports for the heat-exchange tubes. The internal components, such as the primary heat-exchange tubes, secondary heat exchanger, and custom valves, are sourced separately and installed onsite. Also included is a separate module referred to as the Control Valve Deck, which is described as a steel structural platform that will be attached to the third module in the United States. This platform allows physical access to module three and does not contain any mechanical equipment. The fifth module consists of a high-pressure steam drum and an induced draft fan mounted in a structural frame. This module is mounted directly on top of the fourth module. The steam drum is described as a carbon-steel pressure vessel designed to recover heat from the furnace flue gases. The function of the fan is to maintain controlled negative pressure within the furnace by continuously drawing flue gases through the radiant and convection sections. The sixth module is referred to as the Stack and is described as a vertical exhaust chimney that will be mounted atop the convection section of the fifth module. Its function is to vent flue gases, manage emissions, and create a draft (natural or induced) to draw combustion gases from the burners up through the furnace. The last module is referred to as a Stair Tower Module that is assembled to the side of the furnace. This module consists of multiple flights of stairs in an open frame. The stair tower module exists solely to allow physical access to the furnace levels and does not contain any processing equipment. You also requested a classification ruling on two Interconnecting Piping Modules which will be used to connect the subject furnace to the existing furnaces in the complex. These modules will be addressed in a separate ruling. In your submission, you suggest that the Lower Radiant Section, Upper Radiant Section, Convection Sections, Stack, and Very High Pressure Steam Drum and Induced Draft Fan Module are classifiable in heading 8419, Harmonized Tariff Schedule of the United States (HTSUS). You also suggest that the Control Valve Deck and the Stair Tower Module are classifiable in heading 7308, HTSUS. We agree. The applicable subheading for the Lower Radiant Section, Upper Radiant Section, Convection Sections, Stack, and Very High Pressure Steam Drum and Induced Draft Fan Module will be 8419.89.9585, HTSUS, which provides for “Machinery, plant or laboratory equipment, whether or not electrically heated (excluding furnaces, ovens and other equipment of heading 8514), for the treatment of materials by a process involving a change of temperature such as heating, cooking, roasting, distilling, rectifying, sterilizing, pasteurizing, steaming, drying, evaporating, vaporizing, condensing or cooling, other than machinery or plant of a kind used for domestic purposes; instantaneous or storage water heaters, nonelectric; parts thereof: Other machinery, plant or equipment: Other: Other: Other: Other: For other materials.” The general rate of duty will be 4.2 percent ad valorem. The applicable subheading for the Control Valve Deck and the Stair Tower Module will be 7308.90.9590, HTSUS, which provides for “Structures (excluding prefabricated buildings of heading 9406) and parts of structures (for example, bridges and bridge sections, lock gates, towers, lattice masts, roofs, roofing frameworks, doors and windows and their frames and thresholds for doors, shutters, balustrades, pillars and columns) of iron or steel; plates, rods, angles, shapes, sections, tubes and the like, prepared for use in structures, of iron or steel: Other: Other: Other: Other: Other.” The general rate of duty will be free. 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/.

Merchandise is to be classified according to its condition as imported. Should the requirements of 19 CFR § 141.51 and 19 CFR § 141.58 not be met, each component of the system would be separately classified in its own respective heading. 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 the Trade Remedies page at https://www.cbp.gov/trade/programs-administration/trade-remedies. 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 Paul Huang at [email protected].
Sincerely,
(for) James P. Forkan Director National Commodity Specialist Division