1. Chapter 15 Process System Hazards

2. Operating Hazards Equipment and systems Weather
Chemistry and chemicals

3. Equipment and System Related Hazards
Pumps:
Cavitation
Vapor lock
Improper line-up
Variation in suction head or NPSH
Gasket leaks
Seal flush tubing plugs up

4. Figure 15-1 Pump Seal Leak

5. Cavitation
The formation and collapse of air pockets inside the pumping chamber.
Boiling
Cavitation can be prevented by increasing the NPSH or pinching down on the discharge valve.

6. Pressure The force or weight per unit area.
The higher the atmosphere, gas, or liquid the greater the pressure.
Liquid pressure is exerted equally in all directions.
Height of Liquid × × specific gravity = pressure

7. Figure 15-2 Pump System

8. Compressors
Watching flammability limits is important when equipment containing air is purged using gas. If gas enters too slow a flammable mixture is formed. If it enters too fast it can produce a spark.
When selecting a gas to purge with piping line-up is critical.

9. Figure 15-3 Purging Procedure

10. Figure 15-4 Reciprocating Compressor

11. Common compressor safety issues:
Noise hazards
High-pressure hose blowing loose
Hazards associated with compressed gas systems
Hazards associated with rotating equipment
Mixing air and hydrocarbons into flammable or explosive concentrations
Avoiding high-pressure releases; eyes, nose
Fires or explosions
Incorrect line-up
Loss of cooling water
Lifted safety

12. Figure 15-5 Compressed Air System

13. Figure 15-6 Factor of 4 Safety Design

14. Heat Exchangers The effects of absorbed heat:
Increase in molecular activity
Change of state
Chemical change
Energy movement from hot to cold
Radiant heat transfer
Conductive and convective heat transfer
Electrical transfer – thermocouple
Increase in volume
Increase in temperature

15. Figure 15-7 Heat Exchanger System

16. Process technicians use a variety of temperature systems
Process technicians use a variety of temperature systems. The four most common are K, °C, °F, °R.
Heat is a form of energy caused by increased molecular activity that cannot be created or destroyed, only transferred.
The hotness or coldness of a substance determines the temperature.
Heat is measured in BTUs. Temperature is measured in K, °C, °F, °R.
Heat and temperature are not the same.

17. Safety aspects associated with the operation of a heat exchanger system include:
Chemical hazards associated with spills and leaks
Hazards associated with burns
Hazards associated with fires
Hazards associated with explosions and boiling liquid expanding vapor explosion
Confined space entry
Equipment failure
Gauge failure
Sampling, purging, or venting the shell

18. Cooling Tower
Safety aspects of the cooling tower system include the following:
Chemical additives
Rotating equipment
Hazards of hot water
Equipment failure
Working at heights
Hazards of working with acids
Confined space entry
Hazardous energy

19. Figure 15-8 Cooling Tower System

20. Furnace or Fired Heater
In the instance of a flame-out, the concentration of hazardous gases can build up in the furnace until it explodes.
Another common problem is tube leaks. Tube failures are typically related to flame impingement, high heat loads, or erosion.

21. Figure 15-9 Typical Fired Heater

22. Steam Generation
Accidental release of high-, medium-, and low-pressure steam.
High-velocity steam can cut through solid objects.
Steam can eat away the inner surfaces of industrial equipment used to contain it.
Thermal warp, thermal shock, water hammer, and thermal expansion are all natural phenomenon process technicians should be aware.

23. Figure 15-10 Steam Generation – Uses and Applications

24. Figure 15-11 Power Generation System

25. Electricity
The hazards associated with electrical shock are severe and require specific training.
Electrical equipment repair should be performed only by qualified plant electricians.

26. Flare System
When a flare is smoking badly, this is an indication that the plant is having serious problems.
Black smoke from a flare shows unburned hydrocarbons and the loss of company profits.

27. Figure Flare System

28. The hazards associated with flare operation include:
Flare pilot light goes out and heavy hydrocarbon vapors drop to the ground and seek ignition source
Flare header overwhelms flare system and produces black smoke
Fan motor catches fire
Pump goes out on knock-out drum liquid seal and pressure increases on header
Steam ring fails
Support cable breaks during high winds and flare falls

29. Weather-Related Hazards
Lightning is a common occurrence that rarely finds an unprotected or ungrounded system in a plant. It is not safe to be on the tallest vessel or distillation column during a lightning storm.
Heavy rain storms can quickly drop the temperature and cause wide variation swings in process variables.

30. Freezing weather can also cause problems.
Hurricanes present numerous hazards: high winds, flooding, power outage.
The severity of the storm will determine the action plan the plant will use and how much of the facility will be shut down.

31. Chemicals and Chemistry Related Hazards
Chemistry related hazards are associated with the way two or more chemicals will respond to each other under specific operational conditions.

32. Reactors
Reactors are used to make new products by making or breaking chemical bonds.
A reaction is either exothermic or endothermic.

33. Figure 15-13 Stirred Reactor
Fig (p.270)
Figure Stirred Reactor

34. Atoms are composed of positively charged particles called protons, an equal number of neutral particles called neutrons, and negatively charged particles called electrons.
Valence electrons are important because they provide the link to almost every chemical reaction.
Chemical bonding is classified as either ionic or covalent.

35. Matter is anything that occupies space and has mass
Matter is anything that occupies space and has mass. The four physical states of matter are solid, liquid, gas, and plasma.
A compound is defined as a substance formed by the chemical combination of the two or more substances in definite proportions by weight.
A mixture is composed of two or more substances that are only mixed physically.

36. In a chemical reaction, the raw materials or reactants are placed on the left side. As the reactants are mixed together, they yield predictable products. The products are placed on the right side of the equation.
What goes into a chemical reaction must come out.

38. Safety hazards associated with the operation of a stirred reactor include:
Runaway exothermic or endothermic reaction
Feed composition changes cause rapid pressure changes
Fee concentration increase – reaction becomes unstable
Agitation problems will reduce reaction
Loss of cooling water
Loss of catalyst
Temperature increase – doubles reaction rate for every 10°C increase

39. Distillation System
Operational hazards associated with distillation include the following:
Fires and explosions
Leaks – gasket, valve, instruments, piping, and pumps
Pressure surges
Loss of cooling water
Steam valve stuck in open position
Exothermic reaction occurs in the column
Instrument failure

40. Human Factors
Human error has been identified as the most common cause of industrial accidents.
A technician’s greatest nemesis is fatigue and mental stress. Most of the biggest industrial disasters have taken place between the hours of 1:00 A.M. and 4:00 A.M.