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Course 736 - Introduction to Process Safety Management

Safety guides and audits to make your job as a safety professional easier

Process Safety Information

Developing the Written PSM Plan

Employers must compile written process safety information before conducting any process hazard analysis required by the standard. The written process safety information will help the employer and the employees involved in operating the process to identify and understand the hazards posed by those processes that involve highly hazardous chemicals.

To develop an effective PSM program and Process Hazard Analysis (PHA), it is important to develop and maintain complete and accurate written information on each of the following:

  1. process chemicals,
  2. process technology, and
  3. process equipment

This information will be used by:

  • the team performing the process hazard analysis;
  • those developing the training programs and the operating procedures;
  • contractors whose employees will be working with the process;
  • those conducting the pre-startup reviews;
  • local emergency preparedness planners and insurance and enforcement officials.

1. To help identify and understand process hazards, employers must first compile written _____.

a. OSHA permits and authorizations
b. safety inspection results
c. process safety information
d. hazard communication lists

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Hazards of the Chemicals Used in the Process

To develop an effective PSM program and Process Hazard Analysis (PHA), it is important to develop and maintain complete and accurate written information.

The information about the chemicals, including process intermediates, needs to be comprehensive and accurate. Information on the hazards of the highly hazardous chemicals in the process shall consist of at least the following:

  • Toxicity
  • Permissible exposure limits
  • Physical data
  • Reactivity data
  • Corrosivity data
  • Thermal and chemical stability data
  • The hazardous effects of inadvertent mixing of different materials

Current safety data sheets (SDS) can be used to help gather information about hazardous chemicals, but it must be supplemented with process chemistry information, including runaway reaction and over-pressure hazards, if applicable.

2. Which document can be used to help gather process safety information about hazardous chemicals?

a. Safety Data Sheets (SDS)
b. Accident investigation reports
c. Process hazard analysis results
d. Operating procedures

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Technology of the Process

To develop an effective PSM program and Process Hazard Analysis (PHA), it is important to develop and maintain complete and accurate written information.

Process technology information is a part of the process safety information package and should include employer-established criteria for:

  • maximum inventory levels for process chemicals;
  • limits beyond which would be considered upset conditions; and
  • a qualitative estimate of the consequences or results of deviation that could occur if operating beyond the established process limits.

Information on the technology of the process must include at least the following:

  • A block flow diagram or simplified process flow diagram,
  • Process chemistry,
  • Maximum intended inventory,
  • Safe upper and lower limits for such items as temperatures, pressures, flows or compositions, and
  • An evaluation of the consequences of deviations, including those affecting the safety and health of employees.

Where the original technical information no longer exists, information may be developed in conjunction with the process hazard analysis in sufficient detail to support the analysis.

Note: Safety Data Sheets (SDSs) meeting the requirements of the Hazard Communication Standard (20 CFR 1910.1200) may be used to comply with this requirement to the extent they contain the required information.

3. Safe upper and lower limits for such items as temperatures and pressures are required information on the _____ of a process.

a. consequences
b. safety
c. sequence
d. technology

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Types of Process Flow Diagrams

There are different types of diagrams that describe the flow of a process to help employees understand the process in chemical industry or any other industry. Each type of diagram provides specific details of the production process.

Click the button to watch short video on the three basic types of diagrams.

pipinginstrument

Block Flow Diagram (BFDs)

The Block Flow Diagram is the simplest type of diagram and is used to show the major process equipment and interconnecting process flow lines and flow rates, stream composition, temperatures, and pressures when necessary for clarity.

  • A block flow diagram may show the more important operating parameters, such as flow rates and temperature.
  • The process flow consists of chemical process equipment shown as rectangles and squares and the process flow described with arrows.
  • Block flow diagrams do not include pipes, valve, interlock, etc., but only the flow of the process through equipment.

4. Which type of diagram shows only the flow of the process through equipment?

a. Block flow diagram (BFD)
b. Process flow diagram (PFD)
c. Pareto chart (PC)
d. Piping and instrument diagram (PID)

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Process Flow Diagrams (PFDs)

PFDs, also called process flow charts, are a step up from the BFD in the amount of information and data it contains. The PFD contains the most of the data necessary for the design of a process. They show all main flow streams including valves to help understand the process as well as pressures and temperatures on all feed and product lines within all major vessels and in and out of headers and heat exchangers, and points of pressure and temperature control.

  • Information on construction materials, pump capacities and pressure heads, compressor horsepower, and vessel design pressures and temperatures are shown when necessary for clarity.
  • Process flow diagrams usually show major components of control loops along with key utilities.

For more information on process flow diagrams see: The Engineering ToolBox.

5. Which type of diagram is more complex and shows main flow streams, valves, pressures, and temperatures within vessels?

a. Block flow diagram (BFD)
b. Process flow diagram (PFD)
c. Pareto chart (PC)
d. Piping and instrument diagram (PID)

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Piping and Instrument Diagrams (PIDs)

pipinginstrument

Piping and instrument diagrams may be used to describe the relationships between equipment and instrumentation as well as other relevant information that will enhance clarity.

Computer software programs that create PIDs or other diagrams useful to the information package may be used to help meet this requirement.

Information on the equipment in the process must include the following:

  • materials of construction;
  • piping and instrument diagrams (P&IDs);
  • electrical classification;
  • relief system design and design basis;
  • ventilation system design;
  • design codes and standards employed;
  • material and energy balances for processes built after May 26, 1992; and
  • safety systems (e.g., interlocks, detection, or suppression systems).

6. Which of the following tools may be used to describe the relationships between equipment and instrumentation as well as other relevant information to enhance clarity?

a. Block flow diagram (BFD)
b. Process flow diagram (PFD)
c. Pareto chart (PC)
d. Piping and instrument diagram (PID)

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Equipment in the Process

The employer must document that equipment complies with recognized and generally accepted good engineering practices.

For existing equipment designed and constructed in accordance with codes, standards, or practices that are no longer in general use, the employer must determine and document that the equipment is designed, maintained, inspected, tested, and operated in a safe manner.

Compiling and maintaining this information is important to:

pipinginstrument
  • To provide the basis for identifying and understanding the hazards of a process
  • To develop the process hazard analysis
  • Comply with other provisions of PSM such as management of change and incident investigations.

For existing equipment designed and constructed many years ago the employer must:

  • document which codes and standards were used
  • certify that the design and construction along with the testing, inspection, and operation are still suitable for the intended use.

Where the process technology requires a design that departs from the applicable codes and standards, the employer must document that the design and construction are suitable for the intended purpose.

7. When process technology requires a design that departs from the applicable codes and standards, the employer must _____.

a. document suitability for the intended purpose
b. state that the technology complies with CAAA
c. document the technology has been approved by OSHA
d. obtain the related permits for installation

Check your Work

Read the material in each section to find the correct answer to each quiz question. After answering all the questions, click on the "Check Quiz Answers" button to grade your quiz and see your score. You will receive a message if you forgot to answer one of the questions. After clicking the button, the questions you missed will be listed below. You can correct any missed questions and check your answers again.

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Videos

This video compares block flow diagrams (BFDs), process flow diagrams (PFDs), and piping and instrumentation diagrams (PIDs). Made by external faculty and prepared at the University of Colorado Boulder Department of Chemical and Biological Engineering.

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