The document discusses accumulation and overpressure in pressure vessels, defining accumulation as the pressure above the maximum allowable working pressure during high operating events, and overpressure as the pressure above the setting of the relief valve before it actuates. It provides specific thresholds for various types of pressure, including hydro test pressure, maximum allowable accumulation, and operating pressures. Additionally, there is a link to a Udemy course on pipe and fittings for oil and gas careers.

1. Accumulation and
Overpressure
Varun Patel, B.E- Mechanical, PMP®
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2. Accumulation and Overpressure
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Chart Source :http://process-eng.blogspot.com/

3. Accumulation
• Accumulation is pressure above the maximum
allowable working pressure of the vessel that
vessel will experience during the high operating
pressure event
• Accumulation is related to vessel
• Refer chart
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4. Overpressure
• Overpressure is pressure above the setting pressure
of the relief valve that relief valve experience
before pressure start reducing
• Overpressure is related to the pressure relief valve
• Refer chart
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5. Different Types of Pressure for Equipment
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Hydro test Pressure 130% of Design Pressure
Max. Allowable accumulation (fire) 121% of Design Pressure
Max. Allowable accumulation
Multiple valve – Non fire
116% of Design Pressure
Max. Allowable accumulation
Single valve – Non fire
110% of Design Pressure
MAWP (Maximum Allowable Working Pressure) 100% of Design Pressure
(Minimum or more)
Design Pressure
Operating Pressure 90% of Design Pressure
Set Pressure of PSV

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