The PED explorer page explores the different inspection
module options that the directive permits for a given pressure and capacity.
You can use a higher category of inspection on a lower category of equipment,
e.g. you could use module G for any category, even serially produced vessels.
For vessels and steam generators you need to calculate
the enclosed volume in litres and for pipework you need the nominal bore
pipe size in mm
Volume Calculator
To help you calculate volume I have included a calculator
in the explorer. It caters for vessels with flat ends, dished ends
or a conical end. For dished ends you require the head height which
you can measure or compute, depending on their profile as follows:
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2:Ellipsiodal = Inside Diameter / 4
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Hemisphere = Inside Diameter / 2
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Torisphere = Rs - ((Rs-Di/2) * (Rs+Di/2-2*Rn))^0.5
Or Use the 'Calc' Button
Where Rs = Inside Spherical Radius, Rn = Inside
Knuckle Radius, Di = Inside Diameter
(Note this program will probably overestimate the volume
of a Torispherical head as it assumes an elliptical cross section.
The Calculated volume is displayed in the box named
'Capacity'
Using The Explorer
-
Enter the volume or Nominal Pipe Size in mm in the box named
'Capacity'.
-
Enter the pressure in barg
-
Select the button associated with the appropriate chart from
the classification table. This will automatically interpolate the graphs
in the directive and compute the inspection category and briefly state
the inspection options available.
NOTE
-
This Explorer is meant to give you a general idea of what
the directive requires, you must check that the values calculated and the
category selected is correct by referring to the directive before making
any decision regarding manufacture.
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How accurate does the volume have to be calculated? I don't
know, I suggest once you have determined your inspection category, increase
the volume by 10% and see if your category changes, if it does use the
higher category unless it was SEP then a more accurate assessment of the
volume is recommended. The volume for a vessel can include all pipework
up to the first termination point / flange.
-
Generally if the fluid flows through the item its classed
as a pipe, if the fluid is stored in the item it’s a vessel. If the
vessel is made out of pipe it is still classed as a vessel.
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Any data box that is not relevant or zero can be left blank
Page last updated 21 June 2001 |