Valve for sand application

[nur12]

Hi,
Which kind of valve would you suggest for sand application (not slurry, just crude oil / water mix with a small fraction of sand)? Our valves started to leak (even with sealant), so we try to replace it. We want to use a gate valve, but are concerned that the bottom seating area will simply fill with sand and than not seal. Is there some kind of valve specifically designed for high sand service (may be, with backflush capability in the seating area)? What do you use in the similar applications?

 

[stanier]

Valve Technologies have severe service valves with hard coated seats that will give you longer life. I have used these on slurry pipelines with up to Cw%=75 power station ash solids.

 

[Hush]

I'm guessing that what you might be looking for is an API 6A Class II SSV gate valve. Usually a slab gate with stellite or tungsten carbide overlay on seat & gate. Any of the larger 6A valve manufacturers will offer them starting at 2-1/16 bore and up.

 

[nur12]

Thanks for responses.
Stanier, it's actually not a severe service, and not a slurry as well, it's just this sand in oil+water, which scratches our valves... and I'm looking for solution, both effective and reasonable...I mean money...
Hush, thank you, I'll check it out.
Other ideas?

 

[Hush]

I didn't mention that SSV stands for surface safety valve which is actuated, but you can usually order the same valve with a handwheel. The Class II or PR2 are valves that have been 3rd party tested for sandy service.

 

[nur12]

Hush,thanks.
What do you think about (simple solution) metal seated ball valve with drain port or Tomoe Tritec butterfly valve (tripple offset, ellipsoidal sealing geometry)?
And - another question - I assumed that damage on these valves occured because the sand was embedded in the seal (which was nylon) and started to scratch it. But resently I've heard that for most types of valves seal damage occured as a result of construction debris in the pipeline, the tips of welding rods, hand tools, etc., and if we don't already have these type of contaminants, risk of damage occuring is very low. True?

 

[Hush]

All kinds of things have been known to turn up in pipelines when first commissioned, including mobsters. If this is a new startup and the line hasn't been pigged, foreign material damage is entirely possible. You'll have to tear your valve down to find out. At any rate narrowing down the cause of failure couldn't hurt in determining your replacement valve selection. I don't want to comment on the options you've suggested because I'm treading on the edge of my limited expertise as it is. I am thinking though, that if you are experiencing damage from sand abrasion or impingement, that whatever you use should be hardfaced.

 

[stanier]

If its not severe service I would normally use a lubricated plug valve. These are common in the oil patch.

 

[nur12]

Stanier, thanks, I'll definitely consider this possibility.
Hush, nobody knows what caused the problem, why these valves started to leak... We cann't take them apart and have a look, because they are welded, not flanged. I'm just wondering what people usually use for this applications? And how satisfied are they with their choice? I've been talking to many manufacturers, and I suspect that the sentence "Oh, yes, many companies use our valves in their sandy applications" has an invisible continuation "...and they are leaking". I'm looking for perfect choice - it must exist.

 

[TD2K]

We've used Nordstrom plug valves on the North Slope with good success for on/off valves to switch specific wells from production to the test separator.

I can't say how much sand is produced with the crude (though I could work it out) but during the last S/D, the slug catcher had significant amounts of sand to remove.

 

[kumar081070]

PLease specify the purpose of teh valve wether it is isolation or for control of flow . i suppose you should look ffor choke valves . u can go to google search and use Choke Valves as Key word.
regards
Kumar

 

[nur12]

Kumar 081070,
We have sandy, oil, water and oil / water mixes, running through the full port ball valves and also being isolated by the full and regular port ball valves. Both the isolation valves and the normally open valves are not sealing.It is not a marine service...actually, it is a middle of a desert.I'll check choke valves, thank you.
TD2K,thanks,our amount of sand is not significent, just a small fraction, that's why I'm not looking for something expensive and complicated - just for some nice and simple solution. I've been thinking about plug valves, but it appeared our client doesn't want to use plug valves on this project.
Have a nice day!
Inna

 

[kumar081070]

Iam sure that choke valve will suit even non marine application . some of teh reputed choke valve manufacturers are
-- Mokveld valves
-- Masterflow
-- Petrol Valves ( Will be cheaper )
-- Cameron Valves
PLease ensure that you specify all details including teh Chemical composition of fluid , line pressure , temperature , Type odf actuation and other details in your enquiry .
regards

 

[Hush]

You need to define what this valve has to do. A choke valve or butterfly valve will not be appropriate if you require a full through bore.

Also, (this is probably a stupid question but I have to ask it) you mentioned the valve was welded, is it possible the seats were damaged by a post weld heat treat? I've seen teflon seals turned to butter by excess heat during the install weld.

 

[nur12]

Hush, you surprised me...I've never even thought about this from heat treatment point of view...How I can check it? All these valves are part of the system now, and we (OK, people on the field) cann't take them apart because they are not trunnion, but welded. Well, may be, we can exchange one of them and have a look... I greatly appreciate your opinion, thank you.
Kumar081070, I need a full port - Hush was right, it won't work, but thank you for an information - I'm sure, once I'll need it.

 

[kumar081070]

I agree with HUsh . I over looked full bore requirement . I with draw my suggestion for choke valves .
Bye .

 

[bcd]

A little sand in any valve eventually causes damage and leaks. The key is to minimize the damage. One technique is to use metal seats, hard coatings, etc. to limit the amount of wear caused by the sand. Even these eventually loose and the valve is much more expensive to repair. It is also much more expensive to purchase in the first place.

I have had good experience in the identical service with ball valves with plastic seats. The trick is to use a "floating ball" (differential pressure is allowed to push the ball into the seat). Make the downstream seat a solid hard, abrasion resistant plastic like PEEK. It should not have relief grooves, flexure zones, or any other gimics that reduce the contact area with the ball. The downstream seat only acts as a bearing, and holds the ball against the upstream seat. The upstream seat should be a softer, tight sealing polymer. The upstream seat will be the seal, and will provide tight shut-off and long cycle life because the sand impinges and collects on the downstream seat when the valve cycles.

This is the least expensive option. The repair costs on the valve will be much lower than a metal seat, and it works very well.

BR

 

[nur12]

bsd, thanks for idea - it sounds really good.

 

bcd is correct.
A Floating BV with Peek Seats will be the less expensive. The FMC or KF "Compact NB series" will work OK with moderate sand levels, and offer additional weight and space saving advantages. However, it is important to understand the limitations of the Floaters before you start cutting out all your existing valves.

Because the FBV seals on the upstream seat, the cavity can not be bled under normal operating conditions. In addition, the operating torques are much higher than an equivalent Trunnion Mounted BV, and the torques will increase dramatically with age and wear.

Alternatively, you may concider Metal Seated Ball valves with Tungsten Carbide Hard Facing to Seat and Ball. Manufacturers such as Hopkinsons and Petrolvalves routinely meet Class VI Shut Off and this valve type has been manufactured to meet API 6A PSL-3 Gas Tight Bubble Tight Shut Off through the 13.5/8" API 10K sizes (visit ltsusa.com). The disadvantage of this valve technology is that they are much more expensive and are built to order - 16-20+ week typical.

Bottom line, if you want the problem to go away for ever then use a Slab Gate valve with TCC Hardfacing to Seat and Gate. Manufacturers such as Hopkinsons, Petrolvalves and BEL are amongst the world leaders.

Good luck.

 

[nur12]

Thanks,HP Guru, I also think that metal seated ball valve could be the right choice.