One of those days 1

[Danlap]

Dear All, respected valve professionals,

This post may seem contradictive with my previous postings, but I believe that there is some time in our career when we were outnumbered by our non-valve peers and requires “relatively equal” sparing partners to check whether we are still insane.
I am working in a country where “10 How’s” and “10 Why’s/Why not” always asked to challenge one’s experiences. In addition, we are now living in an era where instant solutions is seemingly possible and it is a big word to say NO based on gut feeling.
Never had any experience with solving problem one below in live situation, and never meet people who dare or even survive to tell the story, kindly advise what is the wise (if not the best) way to convey the message.
PS: I've seen this problem several times per year, ever since I started to repair valve (15 years ago), up until now it was up to my team on how to tackle it. But nowadays trend is: "can we do it without killing the Plant??"

1.Problem number one with damage spindle.

Root cause: operator was using some “tool” sort of electro pneumatic “gun” and forgot to stop in close position
Valve general: 4”-2500# gate valve, material SS321, welded, Schedule XXS
Try to see underneath to check whether the bottom spindle crooked or not, the slot between stem and wedge still intact and whether the gland packing rings is borne unequal axial force. No luck, due to wall thickness is 69 mm up to 100 mm we can only see grey area even with the strongest Gamma ray
What is inside: Gas with 5% H2S and some other nasty stuff, pressure 180 bar

Crazy idea which I am outnumbered is my colleagues are figuring out on how to straightening it as current condition without shutting down the Plant. By means of making specific threaded hydraulic jack (which on the making). We will test it on the mockup first, bend one representable valve in the workshop and put it on the test bench, under pressure, and straightening it.
Question:
Is it even possible to do this?
What could go wrong with the mock up and real test? Gland packing wise, and what the simple explanation behind it?
Any “wise” words?

2.Problem number two with cracked open gearbox

Quite straight forward: nodular cast iron gearbox housing, even though valve is manually operated (in theory do not see shock compared to its actuated brother) but after more than 25 years things like this just happened
Constraint: RingO pressure seal (no longer exist) and lead time (3 weeks)
Question: what is better material solutions? Quantity is only 40 something actuator, is another brand usually interchangeable?

Open for mocking, laughter, etc. but preferably constructive advice.

Thank you,
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

 

[jmec87]

Hi Danlap,

I definitely got a laugh and am tempted to mock, but I'll try to be helpful...

For part 1:
Is it possible? Running the test with a sample valve is possible, but duplicating the stem failure might be difficult. The stem in the picture looks completely compromised, as if it will separate into two pieces as soon as it is not being forced together, so this doesn't seem like it will be a useful solution.
What could go wrong with mock-up? Leak of high-pressure fluid if the packing moves suddenly due to the change of position of the stem (from angled to straight or other angle).
What could go wrong with actual valve? Sudden change in packing/stem interaction results in sudden leak. Shooting metal projectiles at high speed due to pressure release and combustion. Leak of H2S and other nasty stuff. Valve that is currently closed (if I understand correctly) suddenly opens.

For part 2:
Are you asking about replacing the housing or the seal?
If the seal, custom seals can often be created in a short time (o-rings in less than a day if spliced or other seals in a couple days if 3D-printed or urethane cast).
If the housing, possibly machine from one part solid steel, or machine from two parts of solid steel and bolt or weld together.

Hope this helps and isn't just a repetition of things you've already thought of...

 

[Danlap]

Hi jmec87,

Thank you for the comments. Appreciate it a lot, as I've mentioned earlier for brain storming purpose with people who had real experience and not influenced by the commercial / business impact effects.
Try not to laugh as well during several meetings, but it is really hard to hold it when in front of me were some stake holder with potential 1 million eur/day shut down.
Fully agree with you, theoretical strain calculation based on deflection and yield only may not reflect actual damage or remaining integrity of current stem. Also, I was trying to mess around with straight stem with 3 bar oil within the valve couple years back and directly "spray" to my face. I cannot imagine what 180 bar explosion would look like.
Hope this not pass the bow-tie process safety matrix assessment.

Some land based (refiners) people think that, "ah lets put it on its backseat and it will be ok". This is completely different with offshore mindset when the whole platform is on stake for any high risk activities.

For part 2 yes it is about replacing of the housing. Good idea to make it simple (may not be pretty) box from solid steel.

Thanks again
regards,

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

 

[Danlap]

Hi All,

Just some update over the mockup test. Fortunately, it works, and (unfortunately) it justifies that we can and will do the exact same thing with real situation under toxic service and 180 bar in the field.
Mockup parameter: same spindle diameter and material as the real valve (in this case 35 mm), similar gate valve, during all activities valve was under pressure with water @25 barg
Goal: to open the valve in full backseat position
Assumption: mock-up bent stem is representing the actual condition
Activities in order: (valve in close position); brace the yoke with two “rings” which had been calculated prior; cut the yoke; pull the spindle by means of slowly retracting the long studs connecting the top and bottom “rings”; always monitor the leakage; once back seat position – remove gearbox – straighten the spindle with pre-prepared hydraulic tools

It is highly risk job, and I do not suggest or encourage people to try this under pressurized system. Just some idea when it is really really really a must do and (almost) all risk have been addressed
What needed:
-(Ideally) mock up test
-A clear understanding of current situation (how is the bending condition, how is the gland condition, valve position, etc.)
-For sure several experience maintenance personnel who can do this job with Swiss watch precision workmanship. and can synchronize movement/communication between one and another
-Gland packing leakage monitor / control
-Pre-calculated bracing tools
-Stinger / gland sealant injection mechanism shall this attempt about to fails
-(if required) tools to straighten the spindle. By the way, It would not be a perfect result
-DO NOT STAND or put your body parts in the line of fire
-Mitigation. As maximum as possible, including clear path to RUN
-Debate, debate and debate. And challenge session(s). and approval from safety and management

With photos as follow (mind the brand unintentionally captured within the photos – they are all good supplier ). I feel the need to share this, but I leave the interpretation of this lesson learned to all of you. BE CAREFUL

Will do the actual action in a few days, cannot take photos. Hopefully everything will be safe

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

 

[LittleInch]

WOW.

I get the bit about how you take the gearbox off, don't agree with the shaft straightening, but think you've already got that, but then what?

You've cut the yoke in half to get the gearbox off and get access to the spindle but how is it going back on?

Can you not undo those 4 bolts you can see on the top picture?
Clearly you've been looking at this for days with all the relevant drawings and parts, but cutting the yoke sounds to me like a one time operation with no way back?

Also did you miss out the line - someone watching on CCTV with their finger poised over the ESD button? I can only hope there are some nearby fast acting ESD valves in case this really starts to go wrong.

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

 

[Danlap]

Thank you for the extra insight LI,

long story short: valve should be open to "wash" the vessel and mitigate the salt induced corrosion. Not part of my specialty (excuse the wording), but more or less that's the idea.

That is indeed point of no return, we cannot undo the 4 bolts (it will be 8 in the real situation) once the yoke is cut. Once back seated, I personally would vote for secure the area or at least that valve area until next replacement, and only use the other valve (by the way this is double block configuration times two set).

Rest is more political (plus some theoretical process concern) rather than technical. They are afraid some water will pass three valves (two DB in series meaning four valve minus this one) and do some damage to the vessel.
So that is why the idea to is mount a hydraulic hand operated actuator mounted in the remaining yoke to make this valve operable. Om which I am against, due to the risk someone may "crush" the packing during the spindle adjustment with this new actuator
Plus removing the yoke is due to the rack and pinion within the gearbox is already compromised.

"someone watching on CCTV with their finger poised over the ESD button?" Unfortunately this is the first valve next to the 180 bar vessel. So literally if something goes wrong, the (full moon suited) workers will have to run and in parallel depressurized the vessel (can take up to 5 hours to reach atmospheric pressure). I am sure there is a ESD button somewhere, but how the process goes I am not sure.
Any smallest and unstoppable gland leakage will initiate this event.

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