EMERGENCY: BALL VALVE BEHAVIOUR UNDER HIGH PRESSURE 2

[GAL02]

Dear all, Good afternoon !
Following is the situation for subject valve;
Valve: Ball Valve
Pressure seal bonnet gasket
Connection: BW
Class: 2500 #
Gear operated (Ratio:275:1)
Service: Synthesis gas
Temp: 50° C
Pressure: 200 Kg/ Cm2
Position: Full open (Suspected 95 % open)
Problem: GEARBOX WORM SHAFT DAMAGE, BUT REMAIN ENGAGE WITH WORM GEAR AT PRESENT.
Question: 1)Can we remove (Disengage gear box from shaft of valve with puller or
by hammering when line is under pressure of 200 Kg/Cm2)?
2)How will be the ball behavior if it became free to rotate?
3)What are the other risks?
All above exercise to avoid SD & huge curtailment.

With regards

 

[Danlap]

Hi GAL02,

Do you have drawing of the valve and the photo of your current situation?
Even with that information there are still some risk associated with this about to be activities.
1) Can we remove (Disengage gear box from shaft of valve with puller or by hammering when line is under pressure of 200 Kg/Cm2)? Yes, but safety measurement is really depending from multi disciplines' point of view. Not actually a ball valve, but some lesson learn from similar activity

http://www.csb.gov/mobile/videos/animation-of-fire-at-exxonmobils-baton-rouge-refinery-/

2) How will be the ball behavior if it became free to rotate? My valve mentor once said, if you're working blind (valve is installed without proper visual clarity for the technicians who are dealing with the gearbox) over ball valve, then you will have NO certainty of its current position. This question was addressed by end user whether it is safe to start PIG-ing after the actuator been re-mounted by not so reliable contractor. Your statement is quite worrying "suspected 95% open" and "disengage gearbox while in that position and full pressure". Yes and No, at some degree of freedom it may rotate
3)What are the other risks? How about your pressure seal condition? Is it on the verge of failing? Imagine you're a rigger with one mission to lift the gearbox no matter what (and believe that everything is already secured 'down there'). He will start to shake/hammer/jacked the gearbox with every force he got and might damage the pressure seal parts, and then incident occurs

Good luck,
Kind regards,
MR

https://nosuchvalve.com

All valves will last for years, except the ones that were poorly manufactured; are still wrongly operated and or were wrongly selected

http://www.eng-tips.com/faqs.cfm?&rat1=2&fid=376

 

[MFJewell]

Here we go again.

 

[LittleInch]

Presumably the same questions and issues as this one of yours...

http://www.eng-tips.com/viewthread.cfm?qid=433389

Sounds to me like you need a plant shutdown to deal with all these valve issues.

Doing this type of work under those sort of operating conditions is a high risk activity made worse by the fact you have no details available.

Is this valve also 50 years old?

You could easily damage the shaft seals and get your fluid jetting out direct onto the workers. At worse the entire shaft can come out acting like an artillery shell followed by the line contents.

Please stop doing this and accept that there are many things that are able to be done while the plant or this section is live and under pressure.

If it's 95% open what's the problem? You can't close it?

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

 

[GAL02]

Dear all, Good morning!
Actually this Petrochemical plant is 60 Years Old, and i am working as a Reliability Engineer.
Periodically (2 Y Frequency) TA is getting conduct but since 2014 there is no TA as
management decided to exit from this business hence with loss of production it is some
times getting pressure from Process to do the job online as mentioned earlier & for this
issue too.

As required for info. pl. find herewith Ball Valve Dwg. Gear Box. internal arrangement (Gen.)
for all of you to get more details.

Thanks for your valuable views & expecting hereafter too.

with regards

 

[GAL02]

Dear Mr. Danlap, Hi !
The link you have send is really educative thanks a lot for the same.
is their any such animation web site or Technical guidance Web where such incidents regarding
different issues can be seen? Pl. share it if any.

With regards

 

[Danlap]

Hi GAL02,

Even though I sympathize your situation, but I agree with comments above. Please DO NOT consider to detach the gearbox during live/pressurized situation without crystal clear information and risk assessment. Without it, it would be a disaster in the making.
Allow me to articulate myself:
a. Please don't use Capital words on the title, some people consider that as yelling and rude. We know you're panicking, but as any other problem in the world, yours is not unique. Gearbox falling apart and valve stuck is also common in my 70 years old Plants as well as in many younger Plants in the world. Doing it without any internal pressure will be A LOT faster, cheaper and SAFER.
b. Be clear on your goal(s)? And we know the main challenge is not the gearbox
You know it is approximately 95% open? So do you need it to be 100% open? Why? Do you know that Cv value (if your Process/owner guys aiming for maximum flow rate) between 95% and 100% opening is not so significant.
Or do you need it to be closed? Why? Does it have Tight Shut off requirement and single barrier to protect other process downstream side of the valve? If yes, then with all due respect that is a wrong concept.
c. Does your company have some sort of Life saving or safety golden rules?
See for point "working on pressurized equipment". One MUST define the potential leakage path and provide clear assessment if things can go wrong. In your case, potential leakage path are body to pressure seal ring connection and gland packing. And since you don't have detail drawing or any Ultrasonic result, then you CANNOT assess the condition. This is a big NO
PS: your drawing is not sufficient
Even doing hot tapping by professional still have to comply strict rules.
d. There is no such thing as no Shutdown. Valve can be considered as a spool or dead end if faulty, but compressor and pump for sure have Run To Fail lifetime or MTBF, and when that happens, that would be your window to repair the valve.
e. Sorry, cannot help with other video. Most incidents are kept within certain internal communication, and only some have been released to public domain. However csb.gov and other websites have many of similar videos, jut google it.
f. Whatever your company planning to do. DO NOT remove the pin between the spindle and the gearbox OR the gearbox removed from the flange. And whenever possible, clamp (and inject sealant within the clamp) between the body to "bonnet" connection to secure the leakage path shall the pressure seal ring fails

Please ask more Senior valve or mechanical engineer within your company, or some reputable (known for its safety) service company's opinion.

Best wishes,
Regards,
MR

https://nosuchvalve.com

All valves will last for years, except the ones that were poorly manufactured; are still wrongly operated and or were wrongly selected

http://www.eng-tips.com/faqs.cfm?&rat1=2&fid=376

 

[GAL02]

Dear Mr. Danlap, Good morning!
Thanks to your and all for valuable guidance in this regard.
it gives me more confident to say 'NO' to highly risky jobs under pressure.

With regards

 

[AzriHms]

Been in a similar situation but with a 40 bar pressure inline. Just remove the gear box.

Regards

 

[GAL02]

Dear all, Good morning!
First of all thanks to all of you who share their views based on Experience & situation.
Here I would like to share my experience for this critical job.
As suggested & then decided to stop the plant & work on it Process given that opportunity
and maintenance remove the Gear Box (GB) by puller & tapping whenever required.
Once GB repaired (Replace the Worm Shaft) and install back with little bit additional effort
and valve taken in line, as soon as it reaches minimum pressure (3 to 5 Kg/Cm2) it starts leaking
from gland bush area, as it is Ammonia it was stopped immediately and we as a Reliability ask to
replace the gland bush ('O' ring).
When maintenance team try to remove gland bush it was not coming easily (Generally it comes out with
no special efforts )then special jack was prepared job plan given how to remove then with great difficulty
it comes up. On inspection we found that inner 'o' ring & its back up ring at top portion is completely gone
(Found in cake form)all other 'o' ring & its back up rings are flattened.
We thanks God that we didn't allow maintenance guys work on it while compressor in it's full swing (10700 RPM) with
220 Kg/ Cm2 pressure discharge, a minor jerk & it would be a disaster for all.
With this Exp. I personally recommend any authority in charge not to give permission to work online for a hazardous
service & high pressure equipment.

This is for information pl.

With regards

 

[LittleInch]

GAL02

Thank you for coming back and letting us know what happened next, not many people do unfortunately.

I'm glad you took on the advice and that the correct and safe operation was undertaken.

AzriHms - I hope not to visit any plants you're working on - you gave out very dangerous advice based on no information. Any maintenance activity on a live plant needs very careful thought and risk assessment and deep knowledge of the item in question. Even then this is only as last resort for such a situation. IMHO.

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