Learned something yesterday

I was working at the natural gas interconnect on erratic flow readings.

This pipeline can handle up to a billion cubic feet per day at about 800 PSI.

We replaced the meters and the valve this summer, but we were not allowed to run the flow up and test. Well they ran the flow up last week and the readings were erratic, so they called me. The control system is tuned to respond with what is determined to be an equal response to what changes in the process, this keeps it in balance. On these, we typically control the flow and "override" or limit to prevent over pressure. We got lucky and they let us crank up the flow to test. I found that it would become erratic when the valve opened more than 25%, and would settle back down when it closed.

Well, it took me back to my schooling. A ball valve opening is not linear, the biggest changes happen when the valve nears the 50% mark and diminish towards the ends. I detuned the response from the controls and it settled right down and worked correctly.

There were two contributing factors to this. First and foremost the insides "trim" of the new valve were not the same size as the old one, which caused much more response to the process when we changed it a certain percentage than the old one. The second factor was that we did not get to test over the full range of control before handing it off to operations. It is not tested unless it is fully tested.

Thanks for listening.

That sort of sounds like when you have cheap ball valves and full flow. Almost twice the volume. You want to watch something really staggering....
If you do competition shooting. All kinds of special "match" bullets but this is crazy. And they are right. Would you ever think of the front of a bullet wearing off????? I don't shoot competition anymore but would sure like to try these.
Super match

Interesting (and scary) stuff. Everyday is a school day. ;^)

<Everyday is a school day.>

I am a firm believer in that and even at my age I love learning something new every day. (actually, with my fading memory even some of the same things seem new).

For control we use the v notch balls in all our control valves. They allow for smoother control thru the whole range.

David,
This pipeline can handle up to a billion cubic feet per day at about 800 PSI.

If I read your post correctly, is a billion Cubic feet a day passes through a ball valve? If so, that has to be one biggie ball. 800 PSI, scares.
Would there be an big explosion if there was any air inside pipeline when 800 psi of natural gas came in contact with the oxygen? (compression ignition)
Geo.

This is a big V notch, think it is 24"

This lines are slowly purged before putting into operation, air in lines is BAD.

BAD as in BOOM BAD?

That's a big valve! We have a few 18" but they are plug style just for shut off not control. They are on dyno feed water so flow is controlled by the vfd on the pumps. The valves on fuel control panels are mostly 3/4" unless feeding a 95 liter.

Yes, boom bad, there are procedures to bleed lines.

I was just reading an article in American Rifleman about cleaning rifle bores and how much copper can accumulate in the bore and how long it takes to really clean them.

We are never too old to learn.
Yes to copper fouling in rifle bores.i shoot lots of 204 ruger.least bit of copper kills accuracy. Sweets 7.62 cleaner is best to rid copper fouling,next i use kroil if out of sweets

David,
We had a Power company gassify coal before sending it to a gas turbine, 1000 psi. Killed 2 people, BOOM BAD! Compression Ingition. That would be very scary to work around.
Geo

We're finishing up an upgrade to our water treatment plant at work, new equipment was manufactured with schedule 80 PVC piping and valves. We had several pipe ruptures that were attributed to vibration/water hammer when the valves were operating too quickly, combined with an engineering flaw that left the downstream pipe empty.

I am not a fan of PVC in industrial applications, have seen too much fail.

Make sure people CLEARLY know that a small PVC coming off a big one is NOT a step, they will snap right off.

Or a handle