Process Deliverables

Material Selection Diagram (MSD)

What is the Material Selection Diagram (MSD)?

The Material Selection Diagram (MSD) is an engineering drawing which shows material selection information and specification of the piping and equipment in a process unit/facility. MSD is normally developed from simplified Process Flow Diagrams (PFDs) by Process Engineer, Material Engineer and the metallurgist of project. The Material Engineer uses the Material Selection Diagram to assign a line class/specification to each line on the Piping and Instrumentation Diagram (P&ID) or Process Engineering Flow Scheme (PEFS).

What the Material Selection Diagram (MSD) show?

A typical Material Selection Diagram (MSD) normally indicates following items:

1. Important equipments in a facility such as pumps, compressor, heater, piping, specific valves, etc.

2. Specify material selected for each of the following equipment and piping itmes
- Columns : shell, internals, tray, lining
- Heat exchanger: shell, channel, tubes, tubesheet, lining
- Air Fan Cooler: headers, tubes, fins
- Tanks: shell, roof, bottom, internals
- Pipeline
- Valve
- Furnaces: coils (convection, radiant, steam), refractory
- Pumps: casing, impeller, pump material group

3. Following material/fabrication requirements are also normally indicated on a Material Selection Diagram (MSD)
- Corrosion allowance
- PWHT or Stress Relieving
- Wet sour service requirements
- Hardness limitation
- Specific impact test requirements (i.e. MDMT, etc.)

4. Following optional information can also be indicated on a Material Selection Diagram (MSD)
- Process data: design/operating
- Corrosion control and monitoring information

  • Corrosion Monitoring Probes/Methods - location & type
  • Chemical Injection - location & type
  • Sampling points
  • Cathodic protection - location & type

- Materials Balances
- percentage of severe corrosive components (e.g. H2, S, H2S, CO2, HF, chloride, etc.)
- Partial pressure of Severe Corrosive Components (e.g. H2, H2S, NH3, HCl, etc.)
- Detail information for spec break in piping (i.e. at valves, tee, cross, dead leg, etc.)
- Specific Notes (e.g. upset condition, short notes for corrosion control, etc.)
- References

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