The document discusses the importance of establishing a thorough design basis for engineering projects. It states that the design basis sets key parameters that impact all aspects of a project, including costs, safety, and operability. It emphasizes that developing the design basis is crucial as decisions made early in conceptual design have significant effects on the overall project. The design basis should document requirements, expectations, site conditions, raw materials and products, utilities, storage, operating philosophy and other factors to properly guide the engineering design.

1. Design Basis

2. Design Basis Considerations
The development of a Design Basis Memorandum (DBM)
should be done for every project undertaken
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• The
and
The
DBM documents the project requirements, expectations
philosophies
DBM benefits and protects the project sponsors and•
project designers by establishing communication
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3. The Importance of Design Basis
• The design basis has tremendous impact
project-
on all aspects
of a
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Investment
Safety
Operability
and Operating Cost
Basic
Design
Engineering
Construction
Operation
Maintenance
Revamp/
HAZOP
Feasibility
Study
Concept
Concept
Constructability
Maintainability
Profitability
• The conceptual and feasibility stage help to set up the
design basis.
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4. The Impact of Initial Phase of
Design Activities
The development of design basis is often overlooked by the owner as well as the
engineering consultant.
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• The conceptual and feasibility stage help to set up the design basis.
• Every single line in a design basis should have thought and analysis behind it. A
thorough study of key issues is needed to establish a proper design basis.
• The graph in the next slide shows the impact of actions taken in early stages of
project.
• The best cost reduction exercise can be done at the design basis stage itself.
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5. The Impact of Initial Phase of
Design Activities
Concept, Design Basis
and Basic Design
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6. Key Issues for
Design
the Process
Basis
1. Project Description 4.
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Raw Material Source and Composition
Raw Material Source
Transportation Mode
Raw Material Composition
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Project Name
Ownership
Brief Description
5.
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Products
Product Slate
Product Specification
Product Destination
Dispatch Mode
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Plant Capacity Related
Capacity
Stream Factor
Turndown Ratio
Operating Philosophy
Safety Management Philosophy 6.
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Battery Limit Related
B/L Definition
B/L Temp. and Pr.
Raw Material & Products
Utilities & Storage
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Location and Site Data
Location Map
Site Map
Site Data
Surrounding Details
Access
7.
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HSE
Environmental Permit / Regulatory Requirements
HSE (or other) project commitments (EIA, QRA, other?) 6

7. Capacity Related Parameters
Capacity is decided based on market survey and projection, which is part of feasibility study.•
• Capacity is defined in a number of ways depending on the type of project.
• Oilfield-
– In oilfield it is described by oil production in BPD or MMTPA, Gas Oil Ratio (e.g. SM3 gas per M3 oil) and
water percent.
Production profile over field life also is important capacity parameter.–
• Refinery-
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Crude Processing capacity in BPSD
Product Slate
• Petrochemical Plants-
– Often defined by product capacity
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8. On-Stream Factor (Plant
On-Stream factor depends on-
Availability)
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Planned maintenance shutdown requirements.
Unplanned shutdowns.
• Normally in a complex process plant, 330 days a year is considered a good basis.
• Some may require operation for a few months or even a few weeks a year.
• But certain critical projects may call for 365 days a year. It is quite common in oil/gas production
facilities.
• On-Stream factor has a huge influence on the process concept and costs of the project.
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Sparing Philosophy
Layers of Protection & Safety Shutdown systems
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9. On-Stream
A basic scheme for oil and
Factor - Exercise
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gas production is given
below. The owner wants to
be able to deliver gas to
the gas pipeline 98% of the
time. What are things to
consider given:
Pipeline
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Separator vessels have a 99% Availability.
Dehydrators require 8 hour regeneration
time every 2 days.
Historical data shows rotating equipment is
available 90% of the time
Control valve loops can fail multiple times
per year and take a few hours
to repair each time
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Treatment
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Or re-injection–
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M
Gas M Cooling
Dehydrator
Gas to
HP Compressor
Separator
LP
Water Oil (Liquid) Separator
Water Atm.
Water Storage
Oil Oil /Liquid
Dehydration Pipeline
Water discharge
Pump

10. Impact of Site Data on Process
Design and Costs
Critical site data for process design are-•
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Contour diagram
Elevation
Maximum Design Ambient Temperature
Minimum Design Ambient
Ambient Pressure
Humidity
Wind Direction
Rainfall data
Temperature
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11. Case Study
How Site Affects Design & Cost
• The scheme below had to be implemented….
Dehydrator Pipeline
Separator
Water Oil (Liquid) (3 bar)
Storage
Oil
Pipeline
Water discharge
• In a hilly terrain like this…. Any advantage of the terrain?
20 M
• Cooling considerations
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M
Natural gas Gas M Cooling Gas to
Well Fluid HP Compressor
(15 bar)
LP
Separator
Water Atm.
Treatment Water 10 MMTPA 600,000 M3 Oil /Liquid
Dehydration
Or re-injection Pump

12. Case Study
Maximum Design Ambient Temp
Metrological department gives temperature profile around the year for several
years.
Designer should recommend maximum and minimum design ambient
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temperatures and maximum solar radiation temperature.
• Propane Refrigerant Make-up Plant
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Desert Location
Maximum Design Ambient Temp.
oCtaken as 55
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oCRequired propane temperature < 50
Turnkey skid mounted supply.
Solar radiation requires protection
against thermal expansion
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Air
Cooler
PACKING
LPG Feed Propane
TRAYS
Butane

13. Wind Direction
Gas Processing Plant producing LPG
out of natural gas
Wind direction reported 75% times
South East to North West
Large Flare to be located 90 M away.
Where shall you locate the flare
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stack? Control Room?
Administration Building?
Muster Points•
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Prevailing
Wind Direction

14. Wind Direction
Bhopal MIC leak was a major disaster.•
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Prevailing
Wind Direction
Thousand died or were affected.
Lesson Learned: Location of a plant
dealing with hazardous materials
must:
Leaked MIC
– Have Emergency Management Plans that
• Identify mitigative measures to manage
risks
– Buffer zones around the plant - downwind
Emergency Response Plan that includes
– Train operators so that they can save
themselves. – understand evacuation plan
and importance of wind direction.
– Community Involvement – ACC Right to
Know
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Operators Escape
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15. Raw Material and Product
Specification
Processing scheme and operating conditions are dictated by
product specification.
The plant needs to be designed with some flexibility on raw
material and product specifications.
The flexibility need to be spelt out in the design basis. Example-
– Range of natural gas composition for a gas processing plant.
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– Gasoline production facility in a refinery to produce to
as international spec.
Resultant product quality considerations include:
Indian spec as well
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The need for online analyzers
Sampling points
Possibly even the need for check tanks
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16. Utilities and Storage
Storage and HandlingUtility Related Issues
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Fuel / Power / Steam
Instrument and Plant
Raw Material Storage Criteria
Raw Material Receipt
Product Storage criteria
Product Dispatch
Intermediate Product Storage
Criteria
Chemical Storage Criteria
Yard Piping
Emission Limitations
– Tank Design
– Vapor Recovery
Air
Raw Water Specification
Cooling Water
Sea Water
Process water
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Effluent Discharge
Flaring Philosophy
Specifications
Major Effluents Summary
Effluent Treatment Requirements
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17. Other
Operation and Maintenance
Issues
• • Buildings and Misc. Offsites
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Equipment Sparing Philosophy
Instrumentation and Control
Philosophy
Safety Shutdown Systems
Operating Philosophy
Office
Maintenance Facilities
Fire Fighting Facilities
Entry Gate
Control Room
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18. Utilities Design
Key Issue
Optimization between Fuel, Power and
importance at today’s energy cost.
Basis
• Steam is of great
• Combined cycle power generation and waste heat utilization
key issues.
are
• Cooling Water vs. Air Cooler is also a key issue.
• Keeping the utility parameters floating at design basis stages
in evolving cost saving concepts.
helps
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19. Storage Design Basis
Key Issues
• Storage has a cost both in terms of investment and inventory cost.
• Storage design basis is dictated by-
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Internal operational requirements
Downstream operators limitations
Engineering limitations- what size of tanks?
Tanker logistics – requiring operations research studies.
• Storage could also be dictated by strategic reasons.
• Keeping the utility parameters floating at design basis stages
concepts.
helps in evolving cost saving
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January 17, 2013

20. Operating Philosophy
Design Basis Key Issues
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Highly automated or not?
Unmanned remote operation totally changes instrumentation
concept.
Unmanned concept is common in oil and gas production, pipelines,
small plants in remote areas.
SCADA with telemetry tele-control concept is utilized in such cases.
Rotating machinery is avoided as far as possible.
For example, remote operated well platforms have solar power
instead of generator for instrument power.
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21. Summary and Conclusion
The Design Basis Communicates Expectations, Requirements
and Preferences
Decisions made in the development of the design basis affects
the concept and cost of the process plant.
Critical Economic Analyses are needed to develop the design
basis
Time spent upfront to develop comprehensive Design Basis will
prevent significant costs in rework later in the project.
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