• PROCESS DESIGN

• SITE SELECTION AND EVALUATION• PLANT LAYOUT AND PLOT PLAN

• CIVIL ENGINEERING DESIGN

• STRUCTURAL ENGINEERING DESIGN

• ARCHITECTURAL DESIGN

• PLANT UTILITIES

PROCESS DESIGN

• PFDs are developed to show major equipment items including sizes, duties, selected operating pressures and temperatures, major control loops and the process flow arrangement.

• Some of the safety elements in PFDs: Process materials properties (CRC and Perry’s Handbooks,

MSDS, CSDS) Process conditions (high and low pressure and temp.) Inventory limits (fewer equipment, fewer protective

devices) Emergency and waste releases Process control philosophy

PRIMARY DATA SOURCES FOR

EXPOSURE LIMITS

• American Conference of Government Industrial Hygienists (ACGIH) – TLV

• Occupational Safety and Health Act (OSHA) –PEL

• American Industrial Hygiene Association (AIHA) – WEEL, ERPG

• National Institute of Occupational Safety and Health (NIOSH) - IDLH

SITE SELECTION

• Important factors in plant siting: Population density around the site (adequate buffer space) Occurrence of natural disasters (weather extremes) Accessibility to raw materials Accessibility to markets Transportation (highways, waterways, airways) Availability of land Availability of power and utilities (adequate water supply) Labor Interface required with other plants (strategic installations nearby) Government policies (siting permits and incentives) Means of pollution and waste and effluent disposal Emergency response support Nearby hazardous installations

SITE EVALUATION

• Credible worst case scenarios

• Reasonable definition of local meteorological conditions and possible extremes

• Population density and numbers of people likely to be involved

• General planning and development guidelines for the region

• Ability to control movement of people in an emergency

PLANT LAYOUT

• Factors of consideration: Minimal explosion damage, since explosion overpressure falls off

rapidly with distance from the center of the explosion Minimal thermal radiation damage, as the intensity also falls off

with the distance Less property damage (containment of accidents) Easier access for emergency services such as fire fighting Easier access to equipment for maintenance and inspection Efficient and safe construction (drainage and grade sloping) Optimum balance among loss control, maintenance and operation

requirements Future expansions• Large impact on plant economics (more spaces increased capital

costs but also enhanced safety – need to optimize)

PLOT PLAN• Facilities that should be separated from each other:

Process units

Tank farms

Outdoor drum storage yards

Loading and unloading stations

Heat transfer fluid heaters and other fired equipment

Flares

Power and boiler houses

Electrical and instrument rooms

Utilities e.g. substations, gas metering stations, nitrogen plants, cooling towers

Control rooms

Warehouses

Fixed fire protection facilities e.g. fire pump houses and reservoirs

Other support facilities such as waste treatment areas, maintenance areas, administrative buildings and laboratories

REFERENCES FOR SAFE SEPARATION DISTANCE

• National Fire Prevention Agency (NFPA 30) –Flammable and Combustible Liquids Code

• NFPA 59A – Liquified Natural Gas

• Center for Chemical Process Safety (CCPS 1988a) –Guidelines for Safe Storage and Handling of High Toxic Hazard Materials

• CCPS 1987 – Guidelines for Use of Vapor Cloud Dispersion Models

• CCPS 1988b – Guidelines for Vapor Release Mitigation

• Industrial Risk Insurers (IRI 1991a, 1992) – Plant Layout and Spacing for Oil and Chemical Plants

CIVIL ENGINEERING DESIGN

• Site preparation:

Geotechnical studies (soil investigation)

Man-made underground obstacles (UG scanning)

• Surface drainage

• Foundations

• Underground piping (utilities, instrument, electrical, process lines – single or double walled)

• Below grade and grade level structures

STRUCTURAL ENGINEERING DESIGN

• Potential natural events:

Seismic considerations

Cold weather protection

Winds

• Open versus closed-in structures (working conditions)

• Access and egress considerations (at least 2 exits)

• Pipe racks (20% > original weight design)

• Elevated structures (fireproofing requirements)

ARCHITECTURAL DESIGN

• Control room design• Explosion-resistant or explosion-proof buildings (add

50-80% cost)• Safe shelter (one part of the building)• Ventilation systems: General ventilation Local ventilation of hazardous areas Ventilation of control room Ventilation following purge with an inert gas or purge

after halon release or building shutdown Ventilation of motor control centers (MCC)

PLANT UTILITIES

• Electricity – pumps, fans, compressors, instrumentation, MOV, agitators

Emergency power supply Uninterruptible power supply – redundant system• Cooling water – condensers, coolers, jackets on rotating

equipment, quench water• Instrument /plant air – transmitters, controllers, ESD,

pneumatic CV, alarm, pumps• Steam – turbine drivers, reboilers, reciprocating pumps,

steam injection, eductors• Fuel oil/gas – boilers, engine drivers, gas turbines• Inert gas – seals, catalytic reactors, purging

• American National Standards Institute (ANSI) A58.1 - Minimum Loads for Buildings and Other Structures

• American Petroleum Institute (API) Recommended Practice (RP) 521 1990 – Guide for Pressure-Relieving and Depressuring Systems

• API RP 941 1990 – Steels for Hydrogen Service at Elevated Temperatures and Pressures in Petroleum Refineries and Petrochemical Plants

• Institute of Electrical and Electronics Engineers (IEEE) Std 447 1980 – Emergency and Standby Power Systems for Industrial and Commercial Applications

• ACGIH 1986 – Industrial Ventilation – A Manual of Recommended Practice

• NFPA 49 1991 – Hazardous Chemicals Data• NFPA 325M 1991 – Fire Hazard Properties of Flammable Liquids• NFPA 491M 1986 – Fire Protection Guide on Hazardous Materials• IRI 1992 – Plant Layout and Spacing for Oil and Chemical Plants