Pressure in Pipeline is Gauge or Absolute

Did you try Wikipedia at all? Or Google, perhaps? I'm not going to do that for you, because that might make you lazy, and we don't want that, do we?

If you have to ask, you should not be doing it.

Are you asking about hoop stress?

Dear Mr.mohsinhamid,

It depends upon how you measure and where you measure.

If you use a bourdon type gauge - measured pressure will be gauge pressure since at atmospheric pressure of 14.696 psi or 1.03 Kg/cm^^2 or 100 kPa. the gauge will show zero pressure.

The point where you measure - upstreme side will be + and downstreme side is - and the correction to be applied for the location of the gauge.

DHAYANANHAN.S

You haven't allowed for the change in barometric pressure due to changes in the local weather.

Yes Mr. Crabtree,

You are absolutely right. The variation as referred by is to be accounted for like Mean Sea Level.

Thanks, for your observation and informing.

DHAYANANDHAN.S

Stop confusing the issue with the facts on the ground. Local changes in barometric pressure probably have not much bearing on the case at hand, unless there is an impending tornado.

In my experience, it is rare to measure PSIA. I cannot recall ever seeing anything that did not just have PSIG as the measure, then again, I am not into instrumentation and do not know what the OP's application is.

Yes.

Both. The measurement units depend on what the measurement instrument references.

Is the pipe open to the atmosphere?

Is it a long pipe or a short pipe?

Is the inside smaller than the outside?

<gauntlet thrown down>

No... the outside is smaller than the inside!

Long or short?

According to my specification, if it's short pipe, it will be unmarked.

However, if it is long pipe, the following applies:

6. All pipe over 500ft (150m) in length should have the words "LONG PIPE" clearly painted on each side and end, so that the contractor knows it's a long pipe.

7. Pipe over 2 miles (3.2km) in length must also have the words "LONG PIPE" painted in the middle, so the contractor will not have to walk the entire length of the pipe to determine whether or not it is a long pipe or a short pipe.

"Is the inside smaller than the outside?"

First, we must establish that one can see through the pipe.

If one cannot see through the pipe it then would follow that the hole is on the outside of the pipe and the inside would then be bigger.

3. The ID (Inside Diameter) of all pipe must not exceed the OD (Outside Diameter) - otherwise the hole will be on the outside.

<groan> ;-)

Really? Where did you pull that from? Don't answer!

The answer depends totally on the type of measuring device used to take the pressure reading.

If it is an absolute gauge or meter you will get absolute values.

If you are asking about the existing pressure in a piping system there are many variables that must be defined such as:

type of fluid

temperature

barometric pressure

open or closed system?

Fluid pressurized by artificial force or gravity alone?

It is absolutely is the pressure reported by this gauge under pressure.

Now my question for you is "What gauge"?

It really just depends on how you look at it!

The pressure in the pipeline will be the same.

This does not mean that the absolute pressure is the same as the gauge one.

There is a difference and you need to find out which one that is!

This is my last contribution to your education.

Your helplessness is obvious in every question you ask.

Your contribution to the forum is nonexistent.

Good luck.

For pumps gauge pressure is ok but for level transmitters(OMEGA etc) should it be absolute pressure.

If it is a 42" compressed natural gas pipeline operating at 1,000 psi, the 15 psi difference between what a gauge pressure and an absolute pressure gauge reads will be very small. The difference between the two is only 1.5%, much too small to be noticed.

Good Luck, Old Salt

For certain compression ratio calculations and the like, you need to use absolute pressure readings. In most pipeline applications, gauge pressure is probably more important. What are you trying to use your readings for?