Stratagy for Preventive Maintenance (Valve) 2

[GAL02]

How to set frequency for valve maintenance, specially PM.
Operation cond'n & physical status is visually monitor but
what about internals?
Suggest the strategy for valve Preventive Maintenance.

 

[Danlap]

Hi,

Unwritten rules of this forum:
a. It's not a sin to say Hi and greet
b. Be clear on the question,
These kind of (short) question repel the seniors to answer question.

Offshore/Upstream or Downstream? Both have different Lifetime expectancy and maintenance mindset (mostly driven by safety and cost)
Manual valve (except Check valve) or Control valve?
Nobody can see through the valve (even X-ray in most cases), therefore the asset owner will need a very good reasons to spend their money on maintenance (which means shutting down the plant).
Thus, you need statistic and diagnostic approach.

A. Statistic (+standardized product)
- Each medium + pressure + temperature will have different valve selection matrix. Check whether your company already have standardization of this.
For offshore (relatively high pressure, low temperature), its clearly defined / stimulated on the OREDA (Offshore Reliability Data) handbook, you will find expected lifetime vs medium there. Preventive maintenance is simply action before its expected lifetime.
For downstream, its much more complex (normally high temperature, relatively low pressure)

Why I mention check valve? Conventional (read: old) plant don't install double barrier check valve after their pump/compressor/turbin. Therefore the likely-hood of its failure is depending on how often is chattering , or even how long its stays open (some hinge become stiff if its remain open for long period).

B. Diagnostic (Control valve)
Use diagnostic measurement on the Positioner. If hysteresis (vs OEM data) measured, then something wrong with your internals (Seat vs Plug or probably also only packing becomes dry or extruded).

There is no easy answer. People developing this for years, and each plant are customized.

Regards,
MR

Greenfield and Brownfield have one thing in common; Valve(s) is deemed to "run to fail" earlier shall compared to other equipments

 

[GAL02]

Dear Muktiadi good morning!
Thanking you for your valuable feedback on the issue.


With regards
Girish

 

[Danlap]

Hi Girish,

You're welcome.
Though, I am not really sure whether I already elaborate enough information. Which of course requires some detail from you.

There are two (general) mindset of Preventive/Predictive Maintenance:
a. "Prevent" the unplanned downtime due to valve failure. Therefore whenever there is indication of poor performance from valve (internal leakage, jerky operation, etc.), start to prevent it from becoming worse / run to fail.
Some ways:
--> First online (if possible), by purging the valve with expectation to clean the sealing area. frequent: depend on how dirty and sticky the medium is against valve's internal
--> re-tune/calibrate the actuator. Frequent: if hysteresis (seating force shifted, etc.) occurs and already disrupt other downstream performance. And potentially will cause nuance trip
--> Re-tightening / replace gland packing. Frequent: operators knows better
etc.
All of course with its own risk and different goals. And not necessarily resolve the real issue.
Most 'windows' to do above activities are during relatively short planned downtime

b. "Maintain" the valve to perform as it is.
Which literally perceived as periodically:
- lubricating the spindle (for rising stem valve) so it will have smooth travelling
- Grease injection (for quarter turn valve), also with expectation of smooth travelling
- Sealant injection (for Normally Close valve), with expectation of tight shut off

Hope you are not aiming for b, since it is only for temporary solution.

Spoiler:
[li]Assuming the valves are manufactured in a perfect manner (dimension, smooth surface and other qualities). Medium and (high and or fluctuated) temperature will contribute more to valve failure rather than High pressure.[/li]
[li]Since tha Alpha Piper incident, offshore valve mindset is more conservative with respect to its general valve lifetime (5 years) and continuously developing its preventive maintenance strategy. Compare to its downstream counterpart (20-25 years). Both have more or less the same safety mindset[/li]
[li]Pressure Safety Valve (PSV) triggered by its criticality and close relation for most incidents in the past. Frequent of inspection is 1 to 3 years (depends on the criticality and governing country).[/li]

Hope I inform you sufficiently. There are lots of literature, books and recommended practice related to this broad subject.

Regards,
MR




Greenfield and Brownfield have one thing in common; Valve(s) is deemed to "run to fail" earlier shall compared to other equipments

 

[GAL02]

Dear Mr. Muktiadi, Good morning!
Really, What you explain are the thing I was expecting, thanks for the same.
Regarding the PSV's as you mentioned the frequency
of inspection is generally 1 to 3 years but if the medium is Ammonia or urea then? it should be vary accordingly?


With regards
Girish A. Lohit

 

[Danlap]

Dear Girish,

This is multidisciplinary matters (Pressure vessel, Process, Inspection and mechanical as the least party), which is closely related with legal matters.
I prefer not provide any answer since I don't know:
a. What kind of pressure vessel these PSVs are protected
b. What type of PSV (Rupture disc, Bellows, conventional, Pilot, etc.)
c. Setting pressure against Operating pressure
d. Is it possible for exothermic reaction shall the PSV fails
e. The most important, what regulations govern the Plant (standard, and legal)

Please use other thread as guidelines, which is also from this forum.

http://www.eng-tips.com/viewthread.cfm?qid=248177

Also consult with your senior inspection or Process personnel (of the plant) and or government re-certification representative will provide you some enlightenment for sure.

Hope I inform you sufficiently.
Regards,
MR


Greenfield and Brownfield have one thing in common; Valve(s) is deemed to "run to fail" earlier shall compared to other equipments

 

[GAL02]

Dear sir, thanking you !
Regarding the procurement, if I want to procure any valve
what should be the format of input (Specification)in RFQ.
For Eg. Globe valve 6"X 300# for Ammonia liq., @low temp & press.
Regulating standards : ASME, API


With regards

 

[GAL02]

Dear all, good morning!
what's difference betw'n USAS & ANSI standard?

With regards
Girish

 

[niteshgargeck]

There are no standard guideline which generally being followed for valve Pm in process industry. Also it depends on the type of valve.
If it is a mechanically operated valve means valve with handle generally greasing is done whenever you get the opportunity.
In case of control valves which are having gear boxed you have to change the soft part of gear box in every shut down if valve is critical and health of actuator should be checked.

 

[Danlap]

Hi,

Sorry, I feel intrigue to respond on above comments.
The statement may be easily perceived by general viewers that greasing is a standard practice and easily be done whenever we like. Which is not entirely correct.
- Grease compatibility against product. Is there any side effect shall they are in contact between each other (polymerization, catalyst, etc.).
- Does the valve equipped with grease nipple (on the bonnet and or body)? How reliable does the grease nipple shall operated frequently? Excessive usage (of this small threaded Non relief valve), may have risk of personnel exposure) or worse

On top of that, grease / lubrication is a temporary solution shall the valve bearing capability (read: Ball vs Seat; Trunnion vs body; Gland packing vs spindle) have already severe minor damage and or loss its permeability (for valve that has not been operated quite sometime).
Exception for above are:
- Lubricated Plug valves (due to its high friction)
- Special valve that indeed require lubrication
- Valve that are subject to be Close (or Open) 1 time after its status quo position (Normally close) in years.

When a common valves requires to be lubricated whenever they are about to be operated, meaning something (surface condition leads to high friction or obstruction) has gone wrong and tend to get worsen.. Thus, need to repair in the next opportunity.

Regards,

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