NBR Import into India: Anti-Dumping Duty Scope Explained

Acrylonitrile-butadiene copolymer is an emulsion-polymerized unsaturated copolymer in which bound acrylonitrile content typically ranges from 18% to 50% by weight. The solid primary form imported into India is classifiable under the Indian Trade Classification subheading 4002 59 00. The latex form falls under 4002 51 00 and is not the subject of the anti-dumping measure applied to solid NBR. The scope of the measure is not controlled solely by the tariff heading; it is product-specific and producer-specific. A technical identification based on bound acrylonitrile content, Mooney viscosity, and polymer morphology determines whether a shipment falls within the anti-dumping net or is excluded as a latex, carboxylated NBR, hydrogenated NBR, or a non-subject elastomer. The customs authority in India applies the measure under Section 9A of the Customs Tariff Act 1975 read with the Customs Tariff (Identification, Assessment and Collection of Anti-Dumping Duty on Dumped Articles and for Determination of Injury) Rules, 1995.

Bound acrylonitrile content is measured according to ISO 24698-1:2018 or equivalent nitrogen analysis, while raw polymer processability is reported as Mooney viscosity ML 1+4 at 100°C under ISO 289-1:2022. These two values are commonly used by customs laboratories and technical evaluation importers to distinguish NBR from polyisoprene, styrene-butadiene rubber, carboxylated nitrile, or a low-acrylonitrile grade that may have been reclassified to reduce the anti-dumping duty burden. The polar nitrile group in NBR controls oil resistance, hydrocarbon penetration resistance, glass transition temperature, and plasticizer retention. This same chemistry determines whether a product described as “nitrile rubber” on an invoice is correctly identified as NBR under the anti-dumping notification, because each exporter schedule is based on a defined chemical and physical product scope.

What limits the usable acrylonitrile window in duty-paid NBR compounding?

Acrylonitrile level is the primary formulation boundary. Low-ACN grades exhibit better low-temperature flexibility but lower resistance to alkane and aromatic hydrocarbon swelling. High-ACN grades provide higher modulus, lower solvent permeability, and better fuel resistance, but their glass transition rises and processing safety margins narrow. The raw polymer Mooney viscosity generally falls between 30 ML and 90 ML 1+4 at 100°C, with specialized crosslinked or powdered grades outside this range.

Mooney viscosity and bound ACN are not independent. A high-ACN NBR with a Mooney value above 90 ML 1+4 at 100°C can generate shear heating above 85°C on open two-roll mills even at low friction ratios. This creates a scorch risk when sulfur donor systems are used. Conversely, a low-ACN NBR with a Mooney value below 40 ML 1+4 at 100°C may exhibit excessive nerve and poor dimensional stability in calendered sheets or extruded profiles. The anti-dumping scope does not set a processing window, but customs laboratories regularly compare declared Mooney viscosity with the producer datasheet to confirm that the imported grade is the declared grade rather than a substituted product.

The table represents typical industrial ranges, not anti-dumping thresholds. When an Indian customs laboratory reports an ACN value outside the range declared in the invoice and the producer datasheet, the shipment can be reclassified within the product scope and assessed at the residual rate. The same applies when the binder system or unsaturation ratio indicates a blend containing SBR or natural rubber. NBR is an unsaturated polymer, and the presence of the nitrile absorption at approximately 2237 cm⁻¹ in infrared spectroscopy is a direct confirmation of nitrile functionality. The ratio of that absorption to the unsaturation region is used in technical disputes.

Compounding of NBR inbound into India is generally carried out on 75–150 kg two-roll mills or in internal mixers with net chamber volumes of 55–120 L. Roll diameter for medium production is typically 450–550 mm with a friction ratio between 1.15:1 and 1.25:1. High-ACN grades require more energy input per kilogram to reach the same carbon black dispersion. Internal mixer discharge temperatures above 95°C are not recommended for sulfur-containing NBR compounds because the residual heat can reduce scorch safety. A two-pass mixing cycle is used for high-filled formulations: the first pass excludes curatives and discharges at 40–60°C; the second pass adds sulfur or peroxide at 85–95°C. Compounds containing amine-based antioxidants should be checked for premature crosslinking because certain amine species can activate sulfur cure at storage temperatures above 35°C.

When the shipment contains latex, carboxylated, or hydrogenated forms, classification changes

Solid non-carboxylated NBR is the primary subject of the Indian anti-dumping measure. Carboxylated NBR, often abbreviated X-NBR, contains carboxylic acid termonomers and is outside the scope in most Indian schedules, but the importer must be able to demonstrate carboxyl content through producer literature and, when demanded, by the relevant titration or infrared method. Hydrogenated acrylonitrile-butadiene rubber is a chemically modified saturated material with different unsaturation levels, different thermal resistance, and a different tariff classification profile. It is generally outside the NBR anti-dumping product definition unless a specific notification wording expands the description. NBR latex is a colloidally dispersed liquid and is excluded from the measure because it is not a solid primary form and is separately classifiable under 4002 51 00.

The classification risk is highest when a shipment is declared as a filled masterbatch, a modified NBR, or a blend. Filled NBR masterbatches containing carbon black or mineral oil can still be within the product scope if the elastomer content dominates and the material remains rubber in primary form under the General Rules for the Interpretation of the First Schedule. If a bale of solid NBR is described on shipping documents as a latex or as a hydrogenated derivative, the burden falls on the importer to supply a producer datasheet, a batch certificate, and independent test evidence. Discrepancies between the declared Mooney viscosity and the measured value under ISO 289-1:2022, or between the declared ACN content and the measured value under ISO 24698-1:2018, are common triggers for scope verification.

Original injury investigation data considered solid NBR from China PR, the European Union, Japan, and Russia. The definitive duty was imposed by Notification No. 15/2017-Customs (ADD) dated 11 April 2017, subject to subsequent amendments and review outcomes. In Indian anti-dumping calculations, the dumping margin is the normal value minus the export price, expressed as a percentage of the export price. The injury margin is the non-injurious price minus the landed value, expressed as a percentage of the landed value. The final duty is generally the lower of the two. Producer-specific rates are assigned to named manufacturers; all other producers from the subject countries receive the residual rate. The landing value for this calculation includes the assessable value under customs law and associated costs as defined in the notification and the Rules, not merely the invoice price.

Vulcanizate performance after immersion in ASTM D471 media

Immersion testing under ASTM D471-16a in IRM 901 and IRM 903 reference oils is used to confirm oil resistance and to detect whether a declared NBR grade is lower in acrylonitrile than represented. A representative medium-ACN compound based on 33 wt% bound acrylonitrile elastomer, 40 phr N330 carbon black, 5 phr zinc oxide, 1.5 phr stearic acid, 1 phr sulfur, and 1.2 phr n-cyclohexyl-2-benzothiazolesulfenamide typically shows a volume change in IRM 901 after 70 h at 100°C of +10% to +20%. The same material in IRM 903 may show a lower swelling value, while a low-ACN grade may exceed +45% in IRM 901. These differences have direct consequences for import verification because a declared high-ACN NBR that swells far beyond the expected range may be a low-ACN substitution or a blend.

Compression set under ISO 815-1:2019 for sulfur-cured NBR after 22 h at 100°C is commonly 18–35%. Peroxide-cured high-ACN compounds can produce compression set values of 8–15% after post-cure, but the scorch safety margin narrows. Low-temperature performance is bounded by the temperature retraction method ISO 2921:2005. A 34% ACN grade can have a TR 10 near -25°C to -18°C, while a 20% ACN grade may recover at -40°C or lower. Vulcanizate performance is therefore not a formality in anti-dumping scope disputes; it establishes whether the physical properties are consistent with the declared grade and the end use.

On production-scale injection lines, NBR compounds based on solid imported bales require controlled moisture content. If warehouse humidity exceeds 60% relative humidity, pre-drying at 70–80°C for 2–4 h in a through-air dryer is used to prevent surface porosity. Barrel temperature settings for medium-viscosity NBR typically include a feed zone of 60–80°C, a compression zone of 80–100°C, and a nozzle below 110°C. Clamp force recommendations for technical rubber articles generally fall between 0.4–0.8 tonnes per square centimetre of projected area. Direct contact with copper, brass, or manganese-based equipment should be avoided because these transition metals catalyze oxidative aging of the unsaturated backbone. These processing boundaries are not part of the anti-dumping duty schedule, but they influence whether an imported NBR grade is technically fit for the declared application after duty payment.

Producer-specific duty schedules, residual rates, and the assessment boundary

Anti-dumping duty is a separate line item applied in addition to basic customs duty and integrated goods and services tax. It is not generally available as an input tax credit, and it must be factored into the importer’s landed cost separately from the assessable value. The current notification schedule contains named-producer rates and residual rates for subject countries. Importers who cannot establish producer identity because of incomplete bills of lading, trading-company documentation, or missing manufacturer declarations are assessed at the residual rate. An importer receiving NBR from a trading company in a non-subject country must verify country of origin rather than assume the trading company’s jurisdiction controls the measure.

If the shipment contains NBR from a named producer but the goods are transhipped through a free trade zone or warehouse in a non-subject country, customs authorities may still require production records and freight documentation to support the declared origin. Insufficient provenance supports assessment at the residual rate and may trigger provisional assessment under the customs rules. Conversely, a shipment from a subject country is not automatically dutiable if the product is genuinely outside the product scope because of latex, carboxylated, or hydrogenated chemistry. The importer’s technical filing must show that the material is not merely a different grade of the subject goods.

In a contested classification, the exact physical and chemical identity of the imported NBR is evaluated against the product description in the final finding and the operative customs notification. The test report from the producer is not always determinative; Indian customs may draw samples and compare the measured bound acrylonitrile content, Mooney viscosity, and unsaturation with the declared values. A mismatch between a declared high-ACN compound and measured swelling or infrared data can be used to hold a shipment for scope review. The scope of the anti-dumping duty on NBR import into India therefore includes the primary form, the country of origin, the producer identity, the product description, and the supporting analytical record. The applicable burden is not satisfied by a tariff code alone.