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Join Date: Sep 2008
Location: Vadodara,India
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Difference in Hydrotest pressure as per ASME Sec.VIII Div.1 UG-99(b) & UG-99(c)

01/01/2012 4:51 AM
I know basic difference between both.UG-99 (b) is based on MAWP & UG-99 (c) is based on MAP.
In both cases we measure hydrotest pressure on top of equipment.In both of case liquid is full.
But in case of UG-99 (b) Hydrotest pressure = 1.3 * MAWP * Stress ratio
UG-99 (C) Hydortest pressure = 1.3 * MAP - Head hydro.
My concern is with head hydro why we substract it in case of UG-99 (c) & not in case of UG-99 (b).
In both case liquid is full.What is basis of ASME code behind it.
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Guru
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Join Date: May 2009
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#1

Re: Difference in Hydrotest pressure as per ASME Sec.VIII Div.1 UG-99(b) & UG-99(c)

01/01/2012 5:00 AM

Please remind me what MAP is versus MAWP (maximum allowable working pressure), and also give the full text of these two Code sections. [I don't have immediate access to the Code, but I might be able to explain the difference. No guarantees.]

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#2

Re: Difference in Hydrotest pressure as per ASME Sec.VIII Div.1 UG-99(b) & UG-99(c)

01/02/2012 9:19 PM

You have to consult UG-99(d) to get your reply. for your ready ref. portion is here:

UG99(d) The requirements of UG99(b) represent the minimum standard hydrostatic test pressure required by this Division. The requirements of UG99(c) represent a special test based on calculations. Any intermediate value of pressure may be used. This Division does not specify an upper limit for hydrostatic test pressure. However, if the hydrostatic test pressure is allowed to exceed, either intentionally or accidentally, the value determined as prescribed in (c) above to the degree that the vessel is subjected to visible permanent distortion, the Inspector shall reserve the right to reject the vessel.

I hope this is clear now.

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