Design operating pressures

The set burst pressure should be selected to permit a sufficiently wide margin between it and the vessel s used or design operating pressure and temperature to avoid premature failure due to fatigue or creep of metal or plastic coatings. 

C. Select a design/operating pressure drop, as shown on the curves of Figure 9-21F. Suggested selection basis is as follows ... 

Factor of safety, flow, 56 Design operating pressures, 33, 34 Guide, 36... 

However, truly effective monitoring and control of waterside chemistry requires that these programs be considered from additional perspectives. Control parameters often must be changed, depending on boiler design, operating pressure, or heat flux, and several other useful, independent guidelines and recommendations are available that take... 

The process design engineer selects the tower design operating pressure as follows ... 

Step 1. In this process we want to achieve the desired production rate and control the impurity of normal butane in the isobutane product at 2 mol %. Reactor pressure cannot exceed the design operating pressure... 

Assume motive steam = minimum steam pressure in header less 5 to 10%. Pressure drop on shell side of surface condenser usually <5% of absolute design operating pressure. 

The normal residual heat removal system must be able to remove the fission product heat from the reactor coolant system from the time after shutdown when the reactor coolant system pressure falls below the design operating pressure of ihe normal residual heat removal system of 62 bar (900 psig). 

The new Bayview Terminal had a design operating pressure of 740 pounds per square inch (50 atmospheres or 50 bar) and the accident pipeline was designed for much higher pressures, so it was necessary to install pressure-reduction equipment where the pipeline joined the new terminal. There were three layers of control and safety devices (i) a control valve to throttle the incoming flow, (ii) a pilot-operated spring-loaded relief valve, and (iii) three motor-operated isolation valves. This triple-barrier approach is sound design - a control system, backed-up by two protection systems (the relief valve and the isolation valves). In the event of a problem with the control valve, the relief valve should operate quickly, and only in the event of a fault with the relief valve should the isolation valves ever have been required to operate. 

Example 7.11. Determine the minimum thickness and schedule number for the inner and outer lines of a vacuum-jacketed liquid helium transfer line. Both lines are constructed of 304 stainless steel with a maximum allowable stress of 129.2 MPa. The weld efficiencies may be assumed to be 100%. The nominal diameters of the inner and outer lines are 25 and 50 mm, respectively. The inner line has support points every 5 m. The maximum design operating pressure of the inner line is 800 kPa absolute. 

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