Rubber-Lined Valves for Sea Water Service 1

[jerseyguy]

We continually have reliability problems with industrial-grade, rubber-lined butterfly valves that we use for onstream isolation of our cooling water (sea water)exchangers. We have tried them all --- Crane Centerline, Keystone, etc. We need to be able to find a source for this type of valve (or perhaps an alternate valve type) that we can rely on for both high reliability AND on-the-shelf availability. I am considering trying-out some rubber-lined knife gate valves that are apparently used for corrosive slurry applications. Does ANYONE have any suggestions? This has been a long-term problem at our plant. Thanks for your cooperation!

 

[NGiLuzzu]

jerseyguy,
may I ask what kind of "reliability problems" did you have? Did you try to analize the root causes?

And... why "rubber-lined" only?

Perhaps switching to much higher reliability and longer useful life durations (e.g.: with metal seated valves) may justify higher costs and make the on-the-shelf availability requirement superfluos...?
;-)

Thanks and Regards, 'NGL

 

[ApC2Kp]

jerseyguy,

Some butterfly valves with buna-N lining and seats had swelling of the rubber so that the valves could not shutoff. Replacement valves with EPDM rubber seats appear to have better life. Other butterfly valves with metallic disk (AL-BRZ, or 316SS epoxy coated) with the EPDM seats are also being tried.

Supposedly some epoxy FRP valves are in seawater service, and the unique feature about them is a fire-test rating(!) for oil production platform firewater installations.

http://wwww.advalve.com

 

[gerhardl]

I could perhaps have some suggestions but would like to have more information about size, pressure class operation device (manual or actuator type requirement) and flow to check speed. Temperature? Price expectation /range?

 

[JimCasey]

If Admiralty metal (AL-Brz) is not giving you suitable service, there are vendors offering Nylon-coated discs.
I suppose you could go down to your local marine supply store and buy some zinc anodes to bolt to the discs for galvanic protection.

If the pressure is low and the seawater is laden with sand, valve companies may optionally reduce the diameter of the disc a bit. An "undercut" disc carries a lower shutoff pressure rating, but does not scrub the sand against the liner as forcefully, so it lives thru a greater number of cycles.

We can speculate all day. Both Gerhardl and Anegri have asked about the specifics of the reliability problems.
What's going wrong, and what's your pressure, flowrate, temperature, and particulate load?

 

[Johnnybv]

There are a couple of good options depending on pressure requirements. There now thermoplastic valves available up to 48" in diameter - however they don't have the mechanical strength or pressure ratings of a metal valve. The Nylon coated disk options work well so long as you can avoid pinning or fixing the disk to the shaft (internal drives work better) The reason is that if you put a fastener through the disk, you end up with an angle that is too difficult (sharp) to coat properly. If you go with a coated disk, I'd go for a valve with an internal stem to disk drive.

 

[steamdog]

I am not an expert in this, but just ran across a specification for a new project here for brackish water out of the East River in NYC for lined butterfly valves. It wanted:
Valve internals in contact with the river water (body, stems, seats, discs, etc.) shall be
internally coated with two (2) coats of coal tar epoxy to a minimum dry film thickness of
20 mils.
Any comments??

 

[JimCasey]

Having led a sheltered life, I am unfamiliar with Coal-Tar epoxies. I figured this was a sharp-pencil way to lock down the bid to a specific product.So I googled, and find that Coal-tar epoxies are offered by many suppliers including good-ol Rustoleum.

I pulled this up from the epoxyproducts.com website:
"Coal tar epoxies are essentially a mix of coal tar and epoxy resins (and not all epoxy resins are the same). Coal tar epoxies were at their peak of popularity in the 1960's (???) through about 1990. After that, non-coal tar epoxies replaced coal tar epoxies due largely to health concerns over long term exposure and direct contact (by coating applicators) to the ‘tar'."

I would not think that the sealing edge of the disc would maintain a coating of CTE after a few cycles.

 

[stanier]

Super duplex stainless steel disc and shaft. Body can be Halon coated.

These materials are used in desalination plants.

For high pressure aplications the body can be in super duplex also.

If you do specifiy super duplex use ASTM A995 gr 5A or 6A as it requires more testing at the foundry.

 

[steamdog]

Thanks Jim Casey, this is for the WTC, they are pumping 15,000 GPM each in three pumps using the water instead of cooling towers. There are lots of butterfly valves, up to 36". It may be this old spec they re-used for the coal tar epoxy. My valve manufacturer came back and would like to recommend "Endurobond coating", but they still had stainless stems! As for the disc and other body parts:
C. Valve body shall be cast iron, ASTM A 126, class A or B, with extended neck to suit
insulation thickness.
D. Disc shall be cast iron or nickel alumnimum bronze.
E. Valve seat and stem (shaft) shall be nickel aluminum bronze.

I can get an oppportunity to talk with the specifying engineer to recommend better, newer, more economical and/or long lasting solutions that may be advantageous to the end user (and me if I get to sell this stuff!)

 

[gerhardl]

From my experience, following:

1. International companies in the cooling business tends to choose cheapest possible 'standard solution acceptable valves' and could end up with standard wafer or U-flange type elastic lined, centric butterfly valves.

2. Note: Operation could require different operational modes from the valve, involving at least two-step emergency closing and different throtteling situations, and again have or give requirement for hydraulic, electro-hydraulic or pure electric control operation.

3. If yes to point two: beware of possible cavitation by throtteling, and water speed plus general torque requirements. Weakness for centric valve type is as given by others: increasing torque when swelling and agening of sealing.

4. Materials: stem and stem sealing details super duplex and seawater resistent stem seals, solid construction for longitudal firm positioning, stem construction overdimensioned for torque and at least solid key positioning of disc.

5. Alternative valve construction to improve expected lifetime: double eccentric, double flanged, with seat ring either acceptable ring material walzed into housing or none, against a hard wallcoating itself. Plus for double eccentric valves: no rubber-sticking disc, sealing ring placed on disc and almost plan-parallell closing and opening of disc the first few degrees. Disc free of seat already at the first 2-3 degrees opening.

6. Housing inner coating: modern plastic based more easily accessible and perhaps as good or better/cheaper than older rubber lining. Different types available: enamel 8glass based surface), or probably better for abrasiveness (shell and sand in cooling water) EPC (epoxy ceramics, good resistance to abrasiveness) are available. If enamel is acceptable towards existing degree of abrasivenss the valve does not need a walzed in seat. EPC and seating: unknown but seating ring super duplex could probalby be done.

7. Note: abrasiveness of coastal seawater by sand and shells is often underestimated, storms and floods can stir up and fill water intake area with lots of hard particles, not easily filtered or felled.

8. Erhard, Tyco Waterworks, Germany, among others, can offer this type of double eccentric valves for seawater in different pressure classes, unknown if other than European standard flanges can be offered.

Good luck!

 

[Johnnybv]

The exotic alloy & super duplex options are great - provided there is budget for it. Also, I'd reccomend a valve that removes as much of the corrosive condition away from the internals or moving parts. If you can elliminate the contact surfaces to the disc and seat you are ahead of the game - provided the atmosphere is not corrosive. If you are on the sea side at water's edge, you'll have to coat externally as well. AS we know, Coatings are subject to wear and failure however the coated options tend to be the most cost effective. I'd check out De-salinization OEM's (GE water or Siemens) and see what they use; they handle brackish water on their systems all the time.

 

[NGiLuzzu]

Many de-salinization plants use metal seated valves in Ni-Al-Bz alloys or Duplex steels... but, as Johnnybv says, it depends on the budget

Regards to All, 'NGL

 

[yalkamer]

maybe it has been some time from the last thread but Adams armaturen from germany have many references for such applications. They have also facilities in US. You can ask them for help. We also applied them to Iron steel factory cooling lines. New valves will be delivered in may DN1400

 

[NGiLuzzu]

Also other Manufacturers produce double or triple offset, quarter turn, metal seated valves for sea water... see, for examples, the ones listed in thread408-135872, thread408-64692 and/or thread408-126483 within this Forum.

Other links and references about this kind of valve are listed in thread408-190488.


Hope this helps, 'NGL