Non-distructive inspection 1

[shvet]

Hello everyone

There we have a stirred reactor ~5m3 on an operating process facility. It is fully filled with mixture of polymer, monomers and solvent (no vapor space). It has a jacket and internal coils for cooling. We would like to find out real design, thickness and dimensions of jacket and internals (agitator, shaft, coils and so on) to be able to provide a purchase order for another one.

The problem is:
- we have no design drawings of internals (general view only)
- manufacturer is not available
- it is fully welded and have no holes/ports for access

The only ports avalible are inlet/outlet nozzles for process and heat transfer fluids.

What are the options we have? Borescope with a measurement nozzle? Scanning by a powerful source of x-rays? Portable laser or acoustic scanner? Are there any companies specialized in such?

 

[pierreick]

Hi ,
Consider Endoscope , third party are able to perform this kind of work , I mean company dealing with Inspection (mechanical) or cleaning equipment .
Why don't pull out the agitator ? you will have a better access.
my 2 cents
Pierre

 

[EdStainless]

So there is no way to clean this vessel?
Inside laser scan, a bunch of UT measurements, and lot of endoscope work will get you close.
You will need to hire an engineering firm to actually give you a code compliant design.
You need to be able to access the internals to inspect and repair the mixer and the coil.

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P.E. Metallurgy, consulting work welcomed

 

[MJCronin]

No ASME or other nameplate ? ... No vessel registration with the state ? .... Where are you located ?

You state that it has an agitator, but there is no way to gain entrance to the internals ?.... Plaese explain, IMHO, this makes no senese ... has the agitator never been serviced or removed ?

Is there a Relief valve on the system and if so what is the RV set pressure ?

Any idea of the materials of construction ? .... How old is it ??

Do you know what the design/operating pressure of the vessel is ? ..... Do you have any control of your process at all ?

Can you post some pictures of the vessel


MJCronin
Sr. Process Engineer

 

[shvet]

@pierreick
Consider Endoscope
What kind of? We need to measure actual dimensions so a common endocope with sightglass would be useless.
Why don't pull out the agitator ?
A vessel is fully welded. Agitator is unaccessible, it can not be pulled out.
I mean company dealing with Inspection (mechanical) or cleaning equipment.
Inspection is another kind of work. Inspection company has means for inpection and (might be) thickness measurement, but not dimensions measurement.

@EdStainless
So there is no way to clean this vessel?
Yes, there is no.
Inside laser scan
What kind of? How a laser scanner would be put inside?
a bunch of UT measurements
Endoscope/Borescope can be equipped with an UT nozzle?
and lot of endoscope work will get you close.
Close to design but not to drawings for purchase order.
You need to be able to access the internals to inspect and repair the mixer and the coil.
Again - internals and jacket are unaccessible.

@MJCronin
No ASME or other nameplate ?
ASME VIII div. 1, code stamped
No vessel registration with the state ?
State - do you mean USA or any country in the world? Vessel is registered in a related local state organization.
Where are you located ?
ex-USSR
You state that it has an agitator, but there is no way to gain entrance to the internals ?
Exactly - other than inlet/outlet nozzles.
Plaese explain, IMHO, this makes no senese ... has the agitator never been serviced or removed ?
It is not accessible. Agitator is not subject to inspection, cleaning or repair. It has been operating for ~20 years with no problems reported.
Is there a Relief valve on the system and if so what is the RV set pressure ?
Jacket - relief valve 2.2 barg.
Vessel - bursting disk 4.0-4.6 barg
Any idea of the materials of construction ?
SA-516
How old is it ??
Actually there are 10 identical reactors. From 10 to 20 years.
Do you know what the design/operating pressure of the vessel is ?
Vessel
Operating conditions 1.5-2.3 barg @ ~150 °C
Design conditions 65 psig @ 650 °F
Jacket
Operating conditions unknown
Design conditions 40 psig @ 650 °F
Actually I do not understand how this information will help.
Do you have any control of your process at all ?
Yes, we have. Pressure and temperature is controlled by control loops.
Actually I do not understand how this information will help.
Can you post some pictures of the vessel
I have only drawings. I would not like to post drawings as those will not be helpful as my case is common.
If it is important - vessel has nozzles from 6" to 14" and jacket from 3" to 6". Vents, drains, thermowells etc. are 1".

 

[pierreick]

Hi,
Did you check the archives room at the plant location (finance department , purchasing department or maintenance department) , you may find the files with Purchase order , design specification ? This is based on my working experience in Asia . Btw did you investigate with their maintenance technicians or engineers ?
Good luck
Pierre

 

[shvet]

@pierreick
Did you check the archives room at the plant location (finance department , purchasing department or maintenance department) , you may find the files with Purchase order , design specification ?
We did not. Managers from production site sent us drawings and reported they have no better one. We do not trust them.
Btw did you investigate with their maintenance technicians or engineers ?
We did not. It is a possible next step.

Anyway vesssel is fully welded, is not able to be disassembled and has no access ports - it is true.

 

[TiCl4]

Shvet,

Endoscopes aren't likely to be accurate enough for what you need. Also, 3D tank inspections use laser scanning equipment that isn't likely to fit inside the tank through an open nozzle. Most 3D tank scanning offerings I've seen basically required CS entry to get a man inside to operate the equipment. You have a 14" nozzle, which is large enough for most standard 3D laser technology. You'd really need to call a 3D tank inspection company and ask if that is something they can do (insert the 3D scanner and operate it remotely.

Radiological measurement likely won't work either - it penetrates the metal and is only slightly attenuated by it. You can get thickness, but obtaining dimensions of blades/baffles/etc isn't going to happen.

You've already said locating the OEM and obtaining drawings from them is a no go...

Sorry, but if you want an exact replica and 3D scanning is a no-go, you'll likely need to take one out of service, grind the top head weld off, remove the top head, and measure the interior. You can then have the tank head re-welded/inspected and put back into service.

 

[shvet]

@TiCl4
Endoscopes aren't likely to be accurate enough for what you need.
As I understood typical endoscope has accuracy 10µm and ±5%. You believe this level is not enough. Am I right? Correct me and comment please.

https://rapid-tech.com.au/wp-content/uploads/2021/09/Coantec-C65-Datasheet.pdf

Most 3D tank scanning offerings I've seen basically required CS entry to get a man inside to operate the equipment.
What is the meaning of CS entry? Carbon steel?

Sorry, but if you want an exact replica and 3D scanning is a no-go, you'll likely need to take one out of service, grind the top head weld off, remove the top head, and measure the interior. You can then have the tank head re-welded/inspected and put back into service.
The problem is coil nozzles are oriented perpendicular of shaft. There is a high chance that coils are placed between blades of agitator so way those prevent agitator to be pulled out without cutting off coils from shell.
This operation is risky because a whole process unit might be shut down for long time while all coils and head would be cut off and then welded in. We bear in mind that vessels are in operation for up to 20 years and there is a chance internal bearings of agitator shaft (unaccessible) will require a minor repair also.
It is a final option as it is risky, qualified and expensive operation which requires strong arguments to be approved by a principal.

 

[EdStainless]

The issue with bore/endoscopes is that he magnification and calibration are a function of the standoff distance.
In a pipe I can control the centering and alignment, I can't in an open tank.
Seriously, take the oldest one or one that has had issues and cut it up.
Your new ones need to be built to allow opening of them.
Yes flanges and hatches will raise the cost, but will allow you to actually maintain these and make sure that all is correct.
I would wager that the older ones have mixer issues (worn or bent blades).

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

 

[TiCl4]

Shvet,

Echoing EdS's comments on calibration - the accuracy is dependent on your ability to know your standoff distance of what you are picturing. That is the real measure of uncertainty, and we cannot determine if this will give you accurate enough information - it depends on the skill of the operator of the unit as well as the internal configuration allowing him to access enough points to get accurate standoffs.

Sorry for the undefined acronym. CS = confined space

How would the agitator have been installed if the coils are between impellers? If this truly is the case, cut the head off anyways. Disengage the shaft of the agitator from the gearbox, allowing the impeller to drop (gently), and slide the head up the shaft to leave the shaft in the tank. Oh, and measure the original height of the shaft before you drop it so you know the original height of the impellers.

Your best bet is still getting a 3D scanning unit in through that 14" opening. Endoscopes are a secondary option, with unknown accuracy. If neither of those two options works, you don't have any other choice than temporarily removing the head.

 

[shvet]

@EdStainless
I would wager that the older ones have mixer issues (worn or bent blades).
But all of reactors are producing polymer having required quality and capacity. What is the reason to consider one of those is not ok. Sure some problems are likely to be revealed but there is a low chance those are critical.

@TiCl4
How would the agitator have been installed if the coils are between impellers?
As we understood design of reactor:
- horisontal vessel, front bearings are outside, rear bearings are inside
- no vapor space, vessel is fully filled with liquid
- a lot of coil nozzles penetrate shell, those are located on all lenght of shell from head to head
- coils nozzles are collected to inlet/outlet piping manifolds
- shell, heads and process nozzles are jacketed
- shell, heads and jackets are welded together, no bolt joints

As we guess blades are located between coils so way the whole volume of reactor is filled with mixture of fixed coils and rotating blades. This design provides the perfect profile of concentrations and temperature both.

In this case welded heads are argumented - it is not practical to provide dismountable heads as if one would take off front head one could get access only to first front row of blades and coils. One would need to cut off first row of coils and pull out first row of blades to get access to second one and so on. Taking in account that we have ~20 rows of coils and blades and coils are welded to shell it is not practical to provide dismountable heads. Access manholes are not practical as those obstruct jackets.

 

[EdStainless]

In all of these years you have never had a batch foul a reactor?
Never hand a coil or jacket leak?
Never had a mixer bearing fail?

It is possible that these were built with the best materials and methods possible.
Sourcing something like that in the open market will take volumes of specifications and extensive inspection.
No one today would choose to overbuild something like this.
I would tell the plant that either they dig through records and find specs and drawings or they will have to pay to have one of these cut up and documented. That means having everything inside measured and tested. And that will not be cheap.

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

 

[shvet]

@EdStainless
In all of these years you have never had a batch foul a reactor?
No one case for 10 reactors for 20 years. Batch foul is been removing by melting out.
Never hand a coil or jacket leak?
Exactly
Never had a mixer bearing fail?
Front bearings - located outside so it is subject to repair.
Rear bearings - located inside so it is unaccessible.
Exactly - we have no one report of a rear bearing problem for all time.

No one today would choose to overbuild something like this.
It is a disputable point.
The key in my case is consequences of small leaking of coils. Pressure of heat trasfer fluid is higher than pressure of process fluid. If coils are not welded to shell then there is a risk of small undetectable leaking and suibsequent mass unspec of polymer. If I would put all facts and risks, pros and cons to a decision maker today there is a high chance this person would choose fully welded reactor as this kind of design pose less financial risk.