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# Pressure Gauge Ranges For Pressure Testing Of Vessels

05/19/2015 12:23 AM

What is the maximum or minimum of pressure gauge to use for test pressure of 785psi as per ASME 8 Div 1

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#1

### Re: Pressure Gauge ranges for pressure testing of vessels

05/19/2015 12:26 AM

Ordinarily it is desirable for expected gauge readings to be around midscale or so of maximum. In this case, a 1500 psi gauge makes sense, but 1200 or 1250 would also suffice.

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#2

### Re: Pressure Gauge ranges for pressure testing of vessels

05/19/2015 12:37 AM

What code can i reference?

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#4

### Re: Pressure Gauge ranges for pressure testing of vessels

05/19/2015 12:55 AM

How about ASME VIII, Div. 1? If it doesn't say, then just be aware that there isn't necessarily a code for everything.

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#5

### Re: Pressure Gauge ranges for pressure testing of vessels

05/19/2015 1:05 AM

The site below will have the desired information, if you can find it.

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#10

### Re: Pressure Gauge ranges for pressure testing of vessels

05/19/2015 11:47 PM

Can I use my GPS to locate "The standards library" ?

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#13

### Re: Pressure Gauge ranges for pressure testing of vessels

05/20/2015 1:13 PM

You will have as much chance with a GPS as some do with GOOGLE, it seems! -- JHF

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#7

### Re: Pressure Gauge ranges for pressure testing of vessels

05/19/2015 3:20 AM

I agree, I was advised by a pressure gauge manufacturer, many years ago, that a gauge was most accurate at between half and two thirds full scale.

So that's been good enough for me.

Best regards,

John

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#3

### Re: Pressure Gauge ranges for pressure testing of vessels

05/19/2015 12:38 AM

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#6

### Re: Pressure Gauge ranges for pressure testing of vessels

05/19/2015 2:10 AM

I really don't know why you are asking here when a phone call to your insurance company's Engineer/Surveyor would give you an instant answer, Mildred.

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#8

### Re: Pressure Gauge ranges for pressure testing of vessels

05/19/2015 6:33 AM

UG-102 merely mandates the ranges of gages to be used in your test and that the gages must be calibrated and maintained. From there, let's go to UG-91 "The Inspector". UG-91(b) gives the inspector the duty to monitor your Quality Control System. When you contracted with your Authorized Inspection Agency, the assigned inspector(s) had you, or someone within your company, write a Quality Control Program per Mandatory Appendix 10. 10-12 states that you must have in place a system for the "calibration of examination, measuring, and test equipment used in fulfillment of requirements of this division". 10-13 requires you to have a system in place for retention of records of numerous documents and procedures, one of which is hydrostatic test records (including the gage number) and another is nonconformances and dispositions (to address the issue of a gage malfunction and the proposed method of correction or disposal).

This is a long write to say that if you are working to ASME Section VIII, Div, 1, your Quality Control Manager is responsible for already having the answer to you question.

Today, with industrial pressure transmitters commonly available with accuracies of 0.075% at 100:1 turndown, I see no reason that you couldn't buy ONE pressure transmitter, calibrate it yearly, and use it for just about every hydrotest you ever do. Unfortunately the code hasn't caught up to that as most shops still have a forest of pressure gauges to provide the necessary ranges, and these are all sent out yearly for calibration- a waste of money and time.

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#9

### Re: Pressure Gauge Ranges For Pressure Testing Of Vessels

05/19/2015 8:29 AM

ASME B40.100-2005 4.3.1 Operating Pressure. The pressure gauge selected should have a full-scale pressure such that the operating pressure occurs in the middle half (25% to 75%) of the scale. The full-scale pressure of the gauge selected should be approximately 2 times the intended operating pressure.

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#11

### Re: Pressure Gauge Ranges For Pressure Testing Of Vessels

05/20/2015 3:05 AM

That nominal reading at midscale guage range selection design and work practice is kinda part of the craft.

All sorts of analogue indicating instruments are selected that way, makes for easy visual checks, eg panel voltmeters have the needle pointing close to straight up at nominal value

Who here remembers rotating their car/bike tacho's so that red line had the needle pointing just past vertical? Normal oil pressure and temp is normally at or around 12 o'clock too. Rotated some of those too.

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#12

### Re: Pressure Gauge Ranges For Pressure Testing Of Vessels

05/20/2015 3:56 AM

I have always worked on (and most oil companies and testign companies standards have stated) 50-70% of full scale deflection. (there or there abouts) however this is only for analogue dial gauges. This doesn't apply if you are using a good digital gauge.

http://www.crystalengineering.net/xp2i

I use these now, only need one gauge on site instead of the normal 15 or so for a full hydrotest spread. 15k psi range with a 0.1psi resolution!!

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#14

### Re: Pressure Gauge Ranges For Pressure Testing Of Vessels

05/20/2015 8:57 PM

Too true.

Digital gauges still have a finite operating range.

If OP wants to go digital than a 0 to 1600 psi sender is what he needs.

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#15

### Re: Pressure Gauge Ranges For Pressure Testing Of Vessels

05/20/2015 9:55 PM

Many years ago a gauge calibration tech gave me some information that has worked out well. Normal pressure should be within the middle 1/3 of the scale (200# range for 100# normal pressure). It is easier to glance at a gauge and know that things are near desired press with the needle near vertical Or out of range if the needle is near horizontal . He also said gauges are more accurate at mid-range but I never verified that. He also said, if necessary to operate with a dial type gauge it is much easier than a digital because you can "glance" at a dial and know if you are within an acceptable range without having to take more time to read it, I.e. Engage brain. For exact reading a digital provides a more reliable and reproducible figure. Just the same as analog watch can be glanced at and show within minute or two what time it is. Digital requires you to look and read the numbers. Analogs are also much easier to do estimations and guesstimates on. If a very accurate reading is needed calibrate it with a very accurate calibration gauge. For more accurate than that calibrate with a calibration gauge traceable to a NIST STANDARD unit. Pay the extra for a certificate of this accuracy to NIST standard. Good Luck, Old Salt

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#16

### Re: Pressure Gauge Ranges For Pressure Testing Of Vessels

08/24/2015 4:30 PM

Clearly the minimum is the test pressure, otherwise there is risk to the integrity of the gauge during the test!

Reported for consideration as a duplicate thread.

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