Verifying Chilled Water Piping Size

[IanVG]

Rookie question here: I am trying to verify the size of some chilled water piping in a mechanical that was originally remodeled in 1973 (drawn, documented and specifications still available) and modified in the decades since. I am struggling to figure out what a particular size of piping is, especially since several as-builts from different conflict with one another without any indication that any pipe was replaced. I am aware that getting a pocket knife to cut through the insulation to determine its depth is a very bad idea, as the seal preventing condensation would be penetrated, but I am at a loss as how to determine on the field the best way to measure the pipe diameter. Does anyone have an idea of any tools or tricks I can try to use to figure this out? Thank you in advance.

 

[LittleInch]

Can you find an ultrasonic insulation thickness meter and then just measure the circumvent of the lagged pipe?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[1503-44]

What's the flow rate, temperature and pressure drop?

A black swan to a turkey is a white swan to the butcher ... and to Boeing.

 

[miningman]

some sort of infrared thermal camera should provide adequate info to generate at least an initial estimate

 

[LittleInch]

Use a thin needle and the a piece of tape or glue to seal the hole?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[1503-44]

MRI? X-ray? Ask the old guy? :=)

A black swan to a turkey is a white swan to the butcher ... and to Boeing.

 

[TBP]

Order on of these - note that the mini one only does up to 6" pipe. The next 3 to the right all have the same scales, and will measure up to 16" pipe. Note that there are 2 scales, one one for nominal pipe diameter, and one for actual diameter. Cut a slit in the pipe insulation, measure the pipe, then tape the cut. Works like a charm, and resolves no end of arguments on the spot. They were sold as "Pocket Rockets" for decades, but I guess they thought that name wasn't "woke" enough. Anyway...

https://oregonrule.com/orc/product-category/calipers/

 

[hacksaw]

What's the outside diameter of the piping including the insulation?

You might check some of the pipe fittings (flanged) as well. your heat exchangers will also provide some idea of the actual flow taking place if you have someone on site to run the calculations.

Chilled water systems have recommend pipe sizes based on the cooling capacity of your compressors.

 

[IanVG]

Everyone, thanks a million for all the thoughtful and helpful replies. I'll try and address some of the questions posed:

[ol 1]
[li]

Can you find an ultrasonic insulation thickness meter and then just measure the circumvent of the lagged pipe?

I asked around and apparently an ultrasonic insulation depth gauge/meter is not a tool we have on hand. Can you recommend any good brands or devices specifically?[/li]
[li]

What's the flow rate, temperature and pressure drop?

Flow rate is 385 GPM, temperature is around 45F, and I am unclear about which pressure drop exactly you are talking about. The chilled water piping is connected to some coils for a large AHU, and the chilled water is tapping off a district chilled water loop and from a chiller that will soon be demolished.[/li]
[li]

some sort of infrared thermal camera should provide adequate info to generate at least an initial estimate

Interesting idea, do you have a recommendation for a budget friendly tool that can accomplish this? Thinking out loud, I wonder if there is a device that can connect to my iPhone and capture thermal imaging.[/li]
[li]

Use a thin needle and the a piece of tape or glue to seal the hole?

Sometimes the simplest idea is the best! Unfortunately, there is a hard plastic casing surrounding the insulation, but I look around and see if a very strong needle would be able to puncture it somewhere.[/li]
[li]

MRI? X-ray? Ask the old guy? :=)

MRI? X-ray? Haha, I assume you are joking, but if you aren't, please fill me in! And trust me, my first go-to with these kinds of questions (after of course some personal digging and research) is to go ask the old guys![/li]
[li]

Order on of these - note that the mini one only does up to 6" pipe. The next 3 to the right all have the same scales, and will measure up to 16" pipe. Note that there are 2 scales, one one for nominal pipe diameter, and one for actual diameter. Cut a slit in the pipe insulation, measure the pipe, then tape the cut. Works like a charm, and resolves no end of arguments on the spot. They were sold as "Pocket Rockets" for decades, but I guess they thought that name wasn't "woke" enough. Anyway...

https://oregonrule.com/orc/product-category/calipe...

Cool! I looked into the tool you suggested and brought up to my boss, but he was concerned that if I were to cut into the pipe, (even if I were to 'tape the cut') that some exposed portion of the pipe/exposed insulation could begin to sweat, which he said, should be avoided at all costs. If anyone has personal experience of doing this and confirm/deny this that would be great! I might get one of these tools regardless, as they look fun to use.[/li]
[li]

What's the outside diameter of the piping including the insulation?

You might check some of the pipe fittings (flanged) as well. your heat exchangers will also provide some idea of the actual flow taking place if you have someone on site to run the calculations.

Chilled water systems have recommend pipe sizes based on the cooling capacity of your compressors.

The outside diameter of the pipe is 8"Ø. And I'll check the flanged pipe fittings to see if that will help. I fortunately know the flow circulating through the coils (only demand for the chilled water piping in this particular building) for the AHU. Interesting point you bring up, because the chilled water is currently being supplied by an in-house chilled but it's also supplying/leaching from district chilled water piping. So I'm not sure if the cooling capacity of the compressors (you mean cooling capacity of the chiller?) would help me in this case.[/li]
[/ol]

I apologize for the long response - I like to be thorough! Thanks again for all the help so far.

 

[Gator]

Are the flanged connections insulated?

 

[1503-44]

You can estimate the diameter, if you know the length of the pipe, number of fittings and the pressure at the beginning and at the end.

I actually like little Inch pin prick method. Do it no matter what your boss says. Just don't tell him.

A black swan to a turkey is a white swan to the butcher ... and to Boeing.

 

[EdStainless]

I have seen both the gage and pins used.
To use the gage you would use a hand saw and slice though the jacket and insulation, measure, and tape over.
If you use pins they need to be pretty stout, more like hat pins.
The trick with pins is to get them in nice and straight.
And make sure that you do them front and back (not top and bottom).
Easy enough to seal over with tape or a dab of sealant.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

 

[TBP]

Ian - Does your boss realize how pipe is insulated? Pipe insulation typically comes in 3 foot half-sections that get wired, taped or banded to the pipe. There are what amount to "cuts" EVERYWHERE after it's installed. That's why insulators cover these joints between the sections (that are inherently left) with tape and/or jacketing.

 

[Abloom]

Measure the circumference of the pipe with insulation in place. Do this with a string, flexible tape, or long piece of paper.
Use your algebra skills to solve for diameter (with insulation). Insulation is specified in standardly available thickness: 1", 1.5", 2", 2.5", etc. Keep in mind there will be two thicknesses of insulation plus your pipe outside diameter, which varies according to specification (ductile iron pipe has a different OD than steel pipe of the same nominal diameter. This method will narrow down the possibilities, while maintaining insulation integrity.