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Order in Council
Department of the Environment

Code of Good Operating Practice for Vinyl Chloride and Polyvinyl Chloride Manufacturing Operations

Download the report in PDF format (337 KB)

P.C. 1991-2486
12 December, 1991

Whereas, pursuant to subsection 8 (1) of the Canadian Environmental Protection Act, the Minister of the Environment has formulated the Code of Good Operating Practice for Vinyl Chloride and Polyvinyl Chloride Manufacturing Operations;

Therefore, His Excellency the Governor General in Council, on the recommendation of the Minister of the Environment, pursuant to section 10 of the Canadian Environmental Protection Act, is pleased hereby to give notice of the Code of Good Operating Practice for Vinyl Chloride and Polyvinyl Chloride Manufacturing Operations, in accordance with the schedule hereto.

I - Vinyl Chloride Fugitive Emissions

Introduction

The quantity of vinyl chloride lost via fugitive sources will vary from plant to plant depending on the type of operating equipment, operating procedures, leak detection and maintenance procedures adopted. The individual sources which may number several hundred in a typical plant can be grouped into categories for the purpose of discussion but the quantity of vinyl chloride being emitted from an individual source at a specific point in time cannot be readily determined. The principal fugitive sources include:

  • pump, compressor and agitator seals
  • pipe flanges and manhole seals
  • valve stems
  • leaking pressure relief valves
  • process quality control sampling sites
  • loading and unloading sites
  • equipment purging operations

Overall plant material balance results, augmented by source monitoring data, have been used to estimate vinyl chloride losses via non-specific or fugitive sources. Estimated emissions from these sources for 1973 were about 1,800 tons representing approximately 35% of total industry emissions for that year. For 1990, the fugitive emissions were estimated to be approximately 30 tons due to the implementation of several control and reduction programs.

Fugitive emissions are generally the result of the normal operations of a chemical plant or a refinery and are generated by the loading/unloading of lines and from equipment such as pumps, compressors, flanges, etc. The first and most essential step that must be taken to minimize these emissions is source detection. This can be accomplished through the use of a multi-point area monitoring system. Such a system used in conjunction with portable detection equipment will enable a plant operator to identify problem areas quickly and to initiate prompt remedial action. Fugitive emissions can be further minimized by improved maintenance schedules.

Over the years, a number of operating procedures have been developed to reduce emissions from the principal fugitive sources which characterize the vinyl chloride industry and the polyvinyl chloride industry. A short description of some of these procedures follows. No attempt bas been made to include all of the control strategies available, and in most cases, equivalent control strategies do exist.

Additional background information pertaining to these control strategies is contained in the EPS publication titled "Air Pollution Emissions and Control Technology: Vinyl Chloride Industry": EPS-3-AP-77-4.

(a) Technology used to reduce fugitive emissions
  1. Leaks front rotary and reciprocating equipment can be minimized by using more effective seals-e.g., double mechanical, seal-less, canned or magnetically driven pumps designs. Vinyl chloride losses from these sources can be further minimized by regular surveillance and maintenance schedules.

  2. Emission from pipe flanges can be minimized by using proper bolting techniques and gasket material. Valve stem leaks could be minimized by using ball/plug valves as minimum technology with additional reductions possible through the use of diaphragm or bellows-type valves, quarter turn valves and "live-loaded" packing on valve stems. Leaks from this and any other types of equipment can be identified by using a multi-point monitoring system in conjunction with portable detection equipment, thereby minimizing the delay in making the necessary repairs.

  3. Leaks from pressure relief valves can occur if the valves do not reseat properly. These leaks can essentially be eliminated by equipping pressure vessels in vinyl chloride service with discs upstream of the safety valve.

  4. Vinyl chloride losses resulting from sampling procedures can be minimized by purging sampling systems to a containment device or back into the process.

  5. Vinyl chloride emissions resulting from loading and unloading operations can be minimized by using closed system transfer facilities. This involves equalizing pressure between the loading or unloading container and the storage tank (accomplished using the vapour pressure of vinyl chloride), attaching loading hoses and transferring the vinyl chloride. A gauging device of closed design-e.g., a float magnetically coupled to a tape system in a pipe isolated from the product---can be used to determine when the transfer operation is complete.

    The material left in any part of the loading or unloading lines may be released to the atmosphere when these are uncoupled. This release can be minimized by implementing adequate closed system purging procedures.

  6. Process equipment in vinyl chloride service must be periodically depressured and opened to atmosphere for inspection and maintenance. The release of residual quantities of vinyl chloride present in this equipment can be minimized by purging these facilities to a containment device.

  7. The slurry strainer is used by some polyvinyl chloride manufacturers to remove lumps of solid polyvinyl chloride which may be present in the slurry. Emissions from this source can be minimized by implementing one of the following strategies:
    1. Relocating the strainer to a point downstream of the stripper and implementing improved stripping techniques;
    2. Enclosing the stripping operation and purging the VCM vapours to a blow-down system;
    3. Installing an in-line delumper.

  8. Some process water streams are contaminated with vinyl chloride which will eventually be lost to the atmosphere. These streams should be collected and stripped to no more than 10 ppm by weight. The vinyl chloride can then be recovered or incinerated. Stripped process water should at least once a month be analysed for vinyl chloride. Records of the analysis should be considered as a part of the fugitive emissions control plan.
(b) Monitors

The following information should be provided:

  • The number of sampling points in the processing area;
  • The analyser detection range;
  • The frequency of sampling at the different points; and
  • The alarm set point concentrations used in the in-plant monitoring system.
(c) Schedule of repairs

A description of the scheduling of actions taken to stop the detected leaks according to their magnitude is to be provided; e.g., a leak of:

  • Level 1 alarm will be stopped within "x" hours from the time of detection or alarm;
  • Level 2 alarm will be stopped within "y" hours from the time of detection or alarm;
  • Level 3 alarm will be stopped within "z" hours from the time of detection or alarm;

as well as the description of the procedures which exist in the plant for the prompt identification and repair of fugitive leaks/losses.

(d) Preventive maintenance program

The program should include an explanation of:

  • The scheduling of refurbishing and/or replacing of parts or equipment;
  • The frequency of inspections and other actions to be taken in respect of the program.
(e) Measurement/Estimation

Once a year, the plant shall provide to the inspector information regarding:

  1. The total estimated vinyl chloride fugitive emissions; and
  2. The method by which this information is obtained.

II - Accidental Release of Vinyl Chloride: Prevention and Preparedness

The Regulations indicate that the owner or operator of a vinyl chloride or a polyvinyl chloride plant shall submit to the Minister a plan to reduce the potential and impact of accidental releases of Vinyl Chloride into the ambient air. Such a plan should contain the following major elements:

  1. Use of available technology, equipment and procedures for the prevention of accidental releases of vinyl chloride, such as:
    1. Using of gas holders or equivalent when practical;
    2. Ensuring alternative power supply and cooling water systems are available;
    3. Using of technology to kill a reaction quickly;
    4. Establishing a good preventive maintenance program;
    5. Carrying out safety inspection after maintenance;
    6. Carrying out safety audit on a periodic basis and after alteration to the process;
    7. Establishing a good training program for employees; and
    8. Investigating causes of malfunctions or breakdowns to minimize causes;

  2. Preparation of different scenarios for potential vinyl chloride releases from different equipment; i.e., determining the maximum quantity or concentration of vinyl chloride which could be released at a certain time front a piece of equipment;

  3. Use of computerized plume modeling programs to predict vinyl chloride concentration at different distances from the release point, for scenarios referred to in subsection (2);

  4. Emergency response plans based on worst case scenarios referred to in subsection (2);

  5. Means for communication of these plans to, and collaboration with, the local municipality in order to integrate the internal plan with the municipality's (this is the part where the impact could be reduced);

  6. Means to make the local public aware of the risks as well as the measures established for its protection, in conjunction with the local municipality (public protection could mean issuing a warning, a notice of evacuation, the order to remain indoors...);

  7. Means to promptly notify the local emergency authorities which would take decisions regarding evacuation and/or public protection, in case of a major release which has the potential of affecting the public.

Explanatory Note

(This note is not part of the Code of Practice.)

In accordance with section 10 of the Canadian Environmental Protection Act, the Governor in Council shall publish, or give notice of, in the Canada Gazette, codes of practice formulated under section 8 or 9 of the Act.

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