38" triple-offset butterfly valve passing - URGENT 2

[thermmech]

Greetings!

We need urgent help

6 pcs of 38" triple-offset butterfly valves are passing (more than 50% of number installed). The valves worked fine for about 12 months. Increasing the torque from 75% to 100% didn't help.

Service: isolation valves for mercury removal filters (dry natural gas)
Class 600#
Pop = 66 barg
DP = 76 barg
Top = 25 C
DT = 82 C
Materials:
body = A351 CF8M
seat = 316SS / Graphite

Plant is 1 year old, there is a possibility of large quantity of dust / scale in the piping. In theory, these valves should be somewhat OK with solids in process fluid.

I haven't had a chance to talk to the OEM, will do that tomorrow.

Any comments on cause, rectification would be much appreciated. If you need more info please advise.

Thank you,
S.

 

[NGiLuzzu]

Back to the original issue with a triple-offset valve from one of the "top rated" Manufacturers, according to thermmech), try to take a look at thread408-183795 and thread408-135872 within this Forum.


Greetings to All, 'NGL
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[jeffvalve]

We have had some success fitting 'Nose Guards' to shield the leading edge of the disc and laminated disc seal from solids in the flow. These are simply a curved piece of 316SS angle welded into the valve body or upstream pipework.

 

[thermmech]

Thanks on your comments - I'll share the findings once we open up the valve and complete inspection which will happen in 6 or so months.

 

[TOVmania]

//anegri - What I witnessed was zero bubble at cryogenic with cycling test done according to Shell 77/300 specification with laminated seats and this company is starting to convince buyers in the market.

//jeffvalve - IMO, you just help prove my previous point. The laminated seat in disc seat type TOV cannot withstand the operating conditions so it needs to add a nose guard. But instead of such add-on, solid metal seat is a better tech to overcome its genetic design shortcoming and a better marketing tool for the disc seat type of TOV. Tyco guys are simply amazing.

 

[NGiLuzzu]

Dear TOVmania,
Your interesting answer raises also more questions.

Where the (possible) bubbles could came from?
What was the length and diameter of the seat leakage collection pipe?
Why not use an electronic mass flowmeter (MFM), for example, instead of a bubble-detecting device?
What about measurement system calibration? I suppose You've seen a Shell TAT which, according to the MESC SPEcification You mentioned, should have been witnessed by a Shell Global Solutions Int'l Inspector... and they are usually quite strict about those quality management system aspects: could You confirm?

And, finally, why... take it out on "Tyco guys"?
As far as I know, who manufacture TOVs within Tyco Group generally do not like nor support the nose guard solution (and they supplied that very rarely indeed), least of all together with laminated seal ring.


Many THANKS in advance for You kind attention and Best Regards,
'NGL
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[TOVmania]

anegri,

1)Shell&Seat Leak Test Performed. Fugitive Emission as well.
2&3&4)I am not to release this information. Sorry.
5)People in the field already know that TOV from Tyco would rather use a solid metal seat ring instead of a nose guard over a laminated seat. I shall clarify what I meant by "Tyco guys are amazing". I said so becausese Tyco overcame disc seat type TOV design disadvantage and applied a solid seat ring to the level of perfection.

Thanks.

 

[TOVmania]

anegri,

For the test, a digital cryogenic recording device was used. A bubble detector was there for a simple reference.

 

[NGiLuzzu]

Dear TOVmania,
THANKS for the clarifications!

There's just one aspect I would like to further deepen, if You agree: so, while the reference bubble detector showed no visible leakage, the digital device recorded "zero.00"?
In which units? SCCM, ml/s, SCF/annum, m³/h, cubic parsec per century or (let me be stupid)... kellicam³ per Qo'noS half-decade, for instance?
Even after a hundred mechanical cycles distributed among at least three (ambient, minimum and maximum) temperature levels?
Against gas (He and/or N₂) at full rated pressure?
In both directions?

And, in the end: how this could be related with the valve performance along time in service (with presence of dust or scale)?

Sorry for being so curious (but the subject tickles my interest)...

Best Regards,
'NGL


- - - - - - - - - - - -


P.S.:
for more references about the issues above ("zero leakage" and Shell MESC SPE 77/300), maybe You'll want to take a look at
- thread408-150132,
- thread408-210466,
- thread408-159429 and
- thread408-259748 ...
within this Forum.

For more complete background examples, see also:
-

http://www.galactic-guide.com/articles/2R137.html

-

http://memory-alpha.org/wiki/Kellicam

;-)

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[thermmech]

We are preparing to open, inspect, and replace soft parts of the seats of these valves. Then we will rotate them to ensure the actual pressure direction matches the preferred preferred direction of the valve.
Will let you know of the outcome.
Thanks on helpful info,