Affirmative defense means, in the context of an enforcement proceeding, a response or defense put forward by a defendant, regarding which the defendant has the burden of proof, and the merits of which are independently and objectively evaluated in a judicial or administrative proceeding.

Batch emission episode means a discrete venting episode that is associated with a single unit operation. A unit operation may have more than one batch emission episode. For example, a displacement of vapor resulting from the charging of a vessel with HAP will result in a discrete emission episode that will last through the duration of the charge and will have an average flowrate equal to the rate of the charge. If the vessel is then heated, there will also be another discrete emission episode resulting from the expulsion of expanded vapor. Both emission episodes may occur in the same vessel or unit operation. There are possibly other emission episodes that may occur from the vessel or other process components, depending on process operations.

Batch operation means a noncontinuous operation involving intermittent or discontinuous feed into process components, and, in general, involves the emptying of the process components after the operation ceases and prior to beginning a new operation. Addition of raw material and withdrawal of product do not occur simultaneously in a batch operation.

Batch process vent means a vent from a batch operation from a PVCPU through which a HAP-containing gas stream has the potential to be released to the atmosphere except that it is required by this subpart to routed to a closed vent system and control device. Emissions for all emission episodes associated with the unit operation(s) are part of the batch process vent. Batch process vents also include vents with intermittent flow from continuous operations. Examples of batch process vents include, but are not limited to, vents on condensers used for product recovery, polymerization reactors, and process tanks.

Bottoms receiver means a tank that collects bottoms from continuous distillation before the stream is sent for storage or for further downstream processing. A rundown tank is an example of a bottoms receiver.

Bulk process means a process for producing polyvinyl chloride resin that is characterized by a two-step anhydrous polymerization process: the formation of small resin particles in a pre-polymerization reactor using small amounts of vinyl chloride monomer, an initiator, and agitation; and the growth of the resin particles in a post-polymerization reactor using additional vinyl chloride monomer. Resins produced using the bulk process are referred to as bulk resins.

Bypass means diverting a process vent or closed vent system stream to the atmosphere such that it does not first pass through an emission control device.

Calendar year means the period between January 1 and December 31, inclusive for a given year.

Capacity means the nominal figure or rating given by the manufacturer of the storage vessel, condenser, or other process component.

Car-seal means a seal that is placed on a device that is used to change the position of a valve (e.g., from opened to closed) in such a way that the position of the valve cannot be changed without breaking the seal.

Closed vent system means a system that is not open to the atmosphere and is composed of piping, ductwork, connections, and, if necessary, flow inducing devices that collect or transport gas or vapor from an emission point to a control device.

Combustion device means an individual unit used for the combustion of organic emissions, such as a flare, incinerator, process heater, or boiler.

Conservation vent means an automatically operated (e.g., weight-loaded or spring-loaded) safety device used to prevent the operating pressure of a storage vessel from exceeding the maximum allowable working pressure of the process component. Conservation vents must be designed to open only when the operating pressure of the storage vessel exceeds the maximum allowable working pressure of the process component. Conservation vents open and close to permit only the intake or outlet relief necessary to keep the storage vessel within permissible working pressures, and reseal automatically.

Container means a portable unit in which a material can be stored, transported, treated, disposed of or otherwise handled. Examples of containers include, but are not limited to, drums, pails, and portable cargo containers known as “portable tanks” or “totes.” Container does not include transport vehicles or barges.

Continuous emission monitoring system (CEMS) means the total equipment that may be required to meet the data acquisition and availability requirements of this subpart, used to sample, condition (if applicable), analyze, and provide a record of emissions.

Continuous operation means any operation that is not a batch operation.

Continuous parameter monitoring system (CPMS) means the total equipment that may be required to meet the data acquisition and availability requirements of this part, used to sample, condition (if applicable), analyze, and provide a record of process or control system parameters.

Continuous process vent means a vent from a continuous PVCPU operation through which a HAP-containing gas stream has the potential to be released to the atmosphere except that it is required by this subpart to routed to a closed vent system and control device and has the following characteristics:

Continuous PVCPU operation means any operation that is not a batch operation or an operation that generates a miscellaneous process vent.

Continuous record means documentation, either in hard copy or computer readable form, of data values measured at least once every 15 minutes and recorded at the frequency specified in § 63.11990(e)(1).

Control device means, with the exceptions noted in this definition, a combustion device, recovery device, recapture device or any combination of these devices used to comply with this subpart. Process condensers are not control devices.

Control system means the combination of the closed vent system and the control devices used to collect and control vapors or gases from a regulated emission source.

Cooling tower means a heat removal device used to remove the heat absorbed in circulating cooling water systems by transferring the heat to the atmosphere using natural or mechanical draft.

Cooling tower return line means the main water trunk lines at the inlet to the cooling tower before exposure to the atmosphere.

Corrective action plan means a description of all reasonable interim and long-term measures, if any, that are available, and an explanation of why the selected corrective action is the best alternative, including, but not limited to, any consideration of cost-effectiveness.

Day means a calendar day, unless otherwise specified in this subpart.

Dioxin/furans means total tetra- through octachlorinated dibenzo-p-dioxins and dibenzofurans.

Dispersion process means a process for producing polyvinyl chloride resin that is characterized by the formation of the polymers in soap micelles that contain small amounts of vinyl chloride monomer. Emulsifiers are used to disperse vinyl chloride monomer in the water phase. Initiators used in the dispersion process are soluble in water. Resins produced using the dispersion process are referred to as latex or dispersion resins.

Empty or emptying means the partial or complete removal of stored liquid from a storage vessel. Storage vessels that contain liquid only as a result of the liquid clinging to the walls or bottoms, or resting in pools due to bottom irregularities, are considered completely empty.

Equipment means each pump, compressor, agitator, pressure relief device, sampling connection system, open-ended valve or line, valve, connector and instrumentation system in HAP service; and any control devices or systems used to comply with this subpart.

Fill or filling means the introduction of liquid into a storage vessel, but not necessarily to capacity.

First attempt at repair, for the purposes of this subpart, means to take action for the purpose of stopping or reducing leakage of organic material to the atmosphere, followed by monitoring as specified in § 63.11930(f) to verify whether the leak is repaired, unless the owner or operator determines by other means that the leak is not repaired.

Fixed roof storage vessel means a vessel with roof that is mounted (i.e., permanently affixed) on a storage vessel and that does not move with fluctuations in stored liquid level.

Flow indicator means a device that indicates whether gas flow is, or whether the valve position would allow gas flow to be, present in a line.

Gasholder means a surge control vessel with a bell that is floating in a vessel filled with water that is used to store gases from the PVC production process prior to being recovered or sent to a process vent control device. The bell rises and falls as low-pressure gases enter and leave the space beneath the bell and the water provides a seal between the enclosed gas within the floating bell and the ambient air.

Grade means the subdivision of PVC resin that describes it as a unique resin, i.e., the most exact description of a type of resin with no further subdivision. Examples include low molecular weight suspension resins and general purpose suspension resins.

Hard-piping means pipes or tubing that are manufactured and properly installed using good engineering judgment and an appropriate standard method published by a consensus-based standards organization if such a method exists or you may use an industry standard practice. Consensus-based standards organizations include, but are not limited to, American National Standards Institute (ANSI, 1819 L Street NW., 6th floor, Washington, DC 20036, (202) 293-8020, http://www.ansi.org).

Heat exchange system means a device or collection of devices used to transfer heat from process fluids to water without intentional direct contact of the process fluid with the water (i.e., non-contact heat exchanger) and to transport and/or cool the water in a closed-loop recirculation system (cooling tower system) or a once-through system (e.g., river or pond water). For closed-loop recirculation systems, the heat exchange system consists of a cooling tower, all heat exchangers that are serviced by that cooling tower and all water lines to and from the heat exchanger(s). For once-through systems, the heat exchange system consists of one or more heat exchangers servicing an individual process unit and all water lines to and from the heat exchanger(s). Intentional direct contact with process fluids results in the formation of a wastewater.

Heat exchanger exit line means the cooling water line from the exit of one or more heat exchangers (where cooling water leaves the heat exchangers) to either the entrance of the cooling tower return line or prior to exposure to the atmosphere or mixing with non-cooling water streams, in, as an example, a once-through cooling system, whichever occurs first.

In HAP service means that a process component either contains or contacts a liquid that is at least 5-percent HAP by weight or a gas that is at least 5 percent by volume HAP as determined according to the provisions of § 63.180(d). For the purposes of this definition, the term “organic HAP” as used in § 63.180(d) means HAP. The provisions of § 63.180(d) also specify how to determine that a process component is not in HAP service.

In vacuum service means that the process component is operating at an internal pressure that is at least 5 kilopascals (kPa) (0.7 pounds per square inch absolute) below ambient pressure.

Incinerator means an enclosed combustion device with an enclosed fire box that is used for destroying organic compounds. Auxiliary fuel may be used to heat waste gas to combustion temperatures. Any energy recovery section present is not physically formed into one manufactured or assembled unit with the combustion section; rather, the energy recovery section is a separate section following the combustion section and the two are joined by ducts or connections carrying flue gas. This energy recovery section limitation does not apply to an energy recovery section used solely to preheat the incoming vent stream or combustion air.

Maintenance wastewater means wastewater generated by the draining of process fluid from components in the PVCPU into an individual drain system prior to or during maintenance activities. Maintenance wastewater can be generated during planned and unplanned shutdowns and during periods not associated with a shutdown. Examples of activities that can generate maintenance wastewaters include descaling of heat exchanger tubing bundles, hydroblasting PVCPU process components such as polymerization reactors, vessels and heat exchangers, draining of low legs and high point bleeds, draining of pumps into an individual drain system, draining of portions of the PVCPU for repair and water used to wash out process components or equipment after the process components or equipment has already been opened to the atmosphere and has met the requirements of § 63.11955.

Maximum representative operating conditions means process operating conditions that result in the most challenging condition for the control device. The most challenging condition for the control device may include, but is not limited to, the highest or lowest HAP mass loading rate to the control device, the highest or lowest HAP mass loading rate of constituents that approach the limits of solubility for scrubbing media, the highest or lowest HAP mass loading rate of constituents that approach limits of solubility for scrubbing media.

Maximum true vapor pressure means the equilibrium partial pressure exerted by the total HAP in the stored or transferred liquid at the temperature equal to the highest calendar-month average of the liquid storage or transfer temperature for liquids stored or transferred above or below the ambient temperature or at the local maximum monthly average temperature as reported by the National Weather Service for liquids stored or transferred at the ambient temperature, as determined by any one of the following methods or references:

Miscellaneous vent means gaseous emissions from samples, loading and unloading lines, slip gauges, process wastewater treatment systems and pressure relief devices that are routed through a closed vent system to a control device and that are not equipment leaks.

Nonstandard batch means a batch process that is operated outside of the range of operating conditions that are documented in an existing operating scenario, but is still a reasonably anticipated event. For example, a nonstandard batch occurs when additional processing or processing at different operating conditions must be conducted to produce a product that is normally produced under the conditions described by the standard batch. A nonstandard batch may be necessary as a result of a malfunction, but it is not itself a malfunction.

Operating block means a period of time that is equal to the time from the beginning to end of batch process operations within a process.

Operating day means a 24-hour period between 12 midnight and the following midnight during which PVC is produced at any time in the PVCPU. It is not necessary for PVC to be produced for the entire 24-hour period.

Operating scenario means, for the purposes of reporting and recordkeeping, any specific operation of a regulated process as described by reports specified in § 63.11985(b)(4)(ii) and records specified in § 63.11990(e)(4).

Plant site means all contiguous or adjoining property that is under common control, including properties that are separated only by a road or other public right-of-way. Common control includes properties that are owned, leased or operated by the same entity, parent entity, subsidiary or any combination thereof.

Polymerization reactor means any vessel in which vinyl chloride is partially or totally polymerized into polyvinyl chloride. For bulk processes, the polymerization reactor includes pre-polymerization reactors and post-polymerization reactors.

Polyvinyl chloride means either polyvinyl chloride homopolymer or polyvinyl chloride copolymer.

Polyvinyl chloride and copolymers production process unit or PVCPU means a collection of process components assembled and connected by hard-piping or duct work, used to process raw materials and to manufacture polyvinyl chloride and/or polyvinyl chloride copolymers. A PVCPU includes, but is not limited to, polymerization reactors; resin stripping operations; resin blend tanks; resin centrifuges; resin dryers; resin product separators; recovery devices; reactant and raw material charge vessels and tanks, holding tanks, mixing and weighing tanks; finished resin product storage tanks or storage silos; finished resin product loading operations; connected ducts and piping; equipment including pumps, compressors, agitators, pressure relief devices, sampling connection systems, open-ended valves or lines, valves and connectors and instrumentation systems. A PVCPU does not include chemical manufacturing process units, as defined in § 63.101, that produce vinyl chloride monomer or other raw materials used in the PVC polymerization process.

Polyvinyl chloride copolymer means a synthetic thermoplastic polymer that is derived from the simultaneous polymerization of vinyl chloride and another monomer such as vinyl acetate. Polyvinyl chloride copolymer is produced by different processes, including, but not limited to, suspension, dispersion/emulsion, suspension blending, and solution processes.

Polyvinyl chloride homopolymer means a synthetic thermoplastic polymer that is derived from the polymerization of vinyl chloride and has the general chemical structure (-H2CCHCl-)n. Polyvinyl chloride homopolymer is typically a white powder or colorless granule. Polyvinyl chloride homopolymer is produced by different processes, including (but not limited to), suspension, dispersion/emulsion, blending, and bulk processes.

Pressure relief device means a safety device used to prevent operating pressures from exceeding the maximum allowable working pressure of the process component. A common pressure relief device is a spring-loaded pressure relief valve.

Pressure vessel means a vessel that is used to store liquids or gases and is designed not to vent to the atmosphere as a result of compression of the vapor headspace in the pressure vessel during filling of the pressure vessel to its design capacity.

Process change means an addition to or change in a PVCPU and/or its associated process components that creates one or more emission points or changes the characteristics of an emission point such that a new or different emission limit, operating parameter limit, or work practice requirement applies to the added or changed emission points. Examples of process changes include, but are not limited to, changes in production capacity, production rate, or catalyst type, or whenever there is replacement, removal, or addition of recovery device components. For purposes of this definition, process changes do not include process upsets, changes that do not alter the process component configuration and operating conditions, and unintentional, temporary process changes. A process change does not include moving within a range of conditions identified in the standard batch, and a nonstandard batch does not constitute a process change.

Process component means any unit operation or group of units operations or any part of a process or group of parts of a process that are assembled to perform a specific function (e.g., polymerization reactor, dryers, etc.). Process components include equipment, as defined in this section.

Process condenser means a condenser whose primary purpose is to recover material as an integral part of a batch process. All condensers recovering condensate from a batch process at or above the boiling point or all condensers in line prior to a vacuum source are considered process condensers. Typically, a primary condenser or condensers in series are considered to be integral to the batch regulated process if they are capable of and normally used for the purpose of recovering chemicals for fuel value (i.e., net positive heating value), use, reuse or for sale for fuel value, use or reuse. This definition does not apply to a condenser that is used to remove materials that would hinder performance of a downstream recovery device as follows:

Process tank means a tank or other vessel (e.g., pressure vessel) that is used within an affected source to both:

Process unit means the process components assembled and connected by pipes or ducts to process raw and/or intermediate materials and to manufacture an intended product. For the purpose of this subpart, process unit includes, but is not limited to, polyvinyl chloride production process.

Process vent means a vent stream that is the result of the manifolding of each and all batch process vent, continuous process vent, or miscellaneous vent resulting from the affected facility into a closed vent system and into a common header that is routed to a control device. The process vent standards apply at the outlet of the control device. A process vent is either a PVC-only process vent or a PVC-combined process vent.

Process wastewater means wastewater that comes into direct contact with HAP or results from the production or use of any raw material, intermediate product, finished product, by-product, or waste product containing HAP, but that has not been discharged untreated as wastewater. Examples are product tank drawdown or feed tank drawdown; water formed during a chemical reaction or used as a reactant; water used to wash impurities from organic products or reactants; water used to cool or quench organic vapor streams through direct contact; water discarded from a control device; and condensed steam from jet ejector systems pulling vacuum on vessels containing organics. Gasholder seal water is not process wastewater until it is removed from the gasholder.

Process wastewater treatment system means a specific technique or collection of techniques that remove or destroy the organics in a process wastewater stream to comply with §§ 63.11965, 63.11970, and 63.11975.

Product means a polymer produced using the same monomers and varying in additives (e.g., initiators, terminators, etc.); catalysts; or in the relative proportions of monomers, that is manufactured by a process unit. With respect to polymers, more than one recipe may be used to produce the same product, and there can be more than one grade of a product. Product also means a chemical that is not a polymer, which is manufactured by a process unit. By-products, isolated intermediates, impurities, wastes, and trace contaminants are not considered products.

PVC-combined process vent means a process vent that originates from a PVCPU and is combined with one or more process vents originating from another source category prior to being controlled or emitted to the atmosphere.

PVC-only process vent means a process vent that originates from a PVCPU and is not combined with a process vent originating from another source category prior to being controlled or emitted to the atmosphere.

Recipe means a specific composition from among the range of possible compositions that may occur within a product, as defined in this section. A recipe is determined by the proportions of monomers and, if present, other reactants and additives that are used to make the recipe.

Recovery device means an individual process component capable of and normally used for the purpose of recovering chemicals for fuel value (i.e., net positive heating value), use, reuse, or for sale for fuel value, use, or reuse. Examples of process components that may be recovery devices include absorbers, adsorbers, condensers, oil-water separators or organic-water separators, or organic removal devices such as decanters, strippers (e.g., wastewater steam and vacuum strippers), or thin-film evaporation units. For purposes of this subpart, recovery devices are control devices.

Repaired, for the purposes of this subpart, means equipment that is adjusted or otherwise altered to eliminate a leak as defined in the applicable sections of this subpart; and unless otherwise specified in applicable provisions of this subpart, is inspected as specified in § 63.11930(f) to verify that emissions from the equipment are below the applicable leak definition.

Resin stripper means a unit that removes organic compounds from a raw polyvinyl chloride and copolymer product. In the production of a polymer, stripping is a discrete step that occurs after the polymerization reaction and before drying or other finishing operations. Examples of types of stripping include steam stripping, vacuum stripping, or other methods of devolatilization. For the purposes of this subpart, devolatilization that occurs in dryers or other finishing operations is not resin stripping. Resin stripping may occur in a polymerization reactor or in a batch or continuous stripper separate from the polymerization reactor where resin stripping occurs.

Root cause analysis means an assessment conducted through a process of investigation to determine the primary cause, and any other significant contributing cause(s), of a discharge of gases in excess of specified thresholds.

Sensor means a device that measures a physical quantity or the change in a physical quantity, such as temperature, pressure, flow rate, pH, or liquid level.

Slip gauge means a gauge that has a probe that moves through the gas/liquid interface in a storage vessel and indicates the level of product in the vessel by the physical state of the material the gauge discharges.

Solution process means a process for producing polyvinyl chloride copolymer resin that is characterized by the anhydrous formation of the polymer through precipitation. Polymerization occurs in an organic solvent in the presence of an initiator where vinyl chloride monomer and co-monomers are soluble in the solvent, but the polymer is not. The PVC copolymer is a granule suspended in the solvent, which then precipitates out of solution. Emulsifiers and suspending agents are not used in the solution process. PVC copolymer resins produced using the solution process are referred to as solution resins.

Specific gravity monitoring device means a unit of equipment used to monitor specific gravity and having a minimum accuracy of ±0.02 specific gravity units.

Standard procedure means a formal written procedure officially adopted by the plant owner or operator and available on a routine basis to those persons responsible for carrying out the procedure.

Storage vessel means a tank or other vessel (e.g., pressure vessel) that is part of an affected source and is used to store a gaseous, liquid, or solid feedstock, byproduct, or product that contains organic HAP. Storage vessel does not include:

Stripped resin means the material exiting the resin stripper that contains polymerized vinyl chloride.

Supplemental combustion air means the air that is added to a vent stream after the vent stream leaves the unit operation. Air that is part of the vent stream as a result of the nature of the unit operation is not considered supplemental combustion air. Air required to operate combustion device burner(s) is not considered supplemental combustion air. Air required to ensure the proper operation of catalytic oxidizers, to include the intermittent addition of air upstream of the catalyst bed to maintain a minimum threshold flow rate through the catalyst bed or to avoid excessive temperatures in the catalyst bed, is not considered to be supplemental combustion air.

Surge control vessel means feed drums, recycle drums, and intermediate vessels used as a part of any continuous operation. Surge control vessels are used within an affected source when in-process storage, mixing, or management of flow rates or volumes is needed to introduce material into continuous operations. Surge control vessels also include gasholders.

Suspension blending process means a process for producing polyvinyl chloride resin that is similar to the suspension polymerization process, but employs a rate of agitation that is significantly higher than the highest range for non-blending suspension resins. The suspension blending process uses a recipe that creates extremely small resin particles, generally equal to or less than 100 microns in size, with a glassy surface and very little porosity. The suspension blending process concentrates the resins using a centrifuge that is specifically designed to handle these small particles. Polyvinyl chloride resins produced using the suspension blending process are referred to as suspension blending resins and are typically blended with dispersion resins.

Suspension process means a process for producing polyvinyl chloride resin that is characterized by the formation of the polymers in droplets of liquid vinyl chloride monomer or other co-monomers suspended in water. The droplets are formed by agitation and the use of protective colloids or suspending agents. Initiators used in the suspension process are soluble in vinyl chloride monomer. Polyvinyl chloride resins produced using the suspension process are referred to as suspension resins.

Table 10 HAP means a HAP compound listed in table 10 of this subpart.

Total non-vinyl chloride organic HAP means, for the purposes of this subpart, the sum of the measured concentrations of each HAP, as calculated according to the procedures specified in §§ 63.11960(f) and 63.11980(b).

Type of resin means the broad classification of PVC homopolymer and copolymer resin referring to the basic manufacturing process for producing that resin, including, but not limited to, suspension, dispersion/emulsion, suspension blending, bulk, and solution processes.

Unloading operations means the transfer of organic liquids from a transport vehicle, container, or storage vessel to process components within the affected source.

Wastewater means process wastewater and maintenance wastewater. The following are not considered wastewater for the purposes of this subpart:

Wastewater stream means a stream that contains only wastewater as defined in this section.

Work practice standard means any design, equipment, work practice or operational standard, or combination thereof, that is promulgated pursuant to section 112(h) of the Clean Air Act.