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Gate Valve

Gate Valve

Gate Valve

(OP)
I am asking for wedge material in the gate valves as stated in the API 600 trim 8 the wedge material shall be 13%Cr the manufacturer has deviated to ASTM A216 WCB +13%Cr, Is this acceptable and compatible with the seat material (ASTM A105+ Stellite)?

RE: Gate Valve

Hi Mostafa,

The wedge material of Trim 8 should usually come with Stellite to avoid galling between the seats and wedge.

The term "WCB + 13%Cr" usually means WCB carbon steel with 13%Cr overlay, which is not common unless the service is corrosive and the size of the wedge gate valve is huge.

The recommended pairing should be:
Wedge Material: A216 WCB + Stellite
Seat Material: A105 + Stellite

RE: Gate Valve

I don't agree with @wornandwound, Trim 8 should be a combination trim, the seating surface should be 13% on one side, and Hardfacing on the otherside. For gate valve NPS 2 and above, the most common selection is:
Wedge material: A216 WCB + 13Cr
Seat material: A105 + Stellite 6

Of course, you can specify the wedge material to be solid A217 CA15 (casting material equivalent to 13Cr), then again the price is much higher.

James Chan

RE: Gate Valve

Hello, Mostafa,

Please realize that:
According to API 600, the seating surface (hard faced coating) material for wedge and seat shall be 13Cr or Co-Cr alloy.
The standard does not say the wedge/seat ring material shall be 13 Cr.


Regards

TZL

RE: Gate Valve

The standard say that the base material of the trim should be minimal equal to the body material, so A105 or WCB is accepted.
One of the surfaces (seat or wedge in case of a gate) needs to be hard and there needs to be aminimum and a difference. Don't think there is a requirement how the hardness should be made.

RE: Gate Valve

JChanMe

Gave the right answer IMHO

luis

RE: Gate Valve

I agree with JchanMe as well. Wedge material is a fair bit higher if you use solid A217 CA15 for the valve

RE: Gate Valve

Just FYI. A217 CA15 is "acceptable" replacement for WCB with 13CR overlay. for smaller valves, this is much easier to manufacture.

I say this because when's the last time you've seen an A217 CA15 PT rating?

Luke | Valve Hax | https://valvehax.com/

RE: Gate Valve

API Trim Number 8
Nominal Trim
410 - Hard faced
Trim code
F6HFS
Stem and other trim parts
410 (13Cr) (200-275 HBN)
Disc/wedge
410 (13Cr) (250 HBN min)
Seat surface 410+St Gr6 (CoCr Alloy) (350 HBN min)
Trim Material Grade
13Cr-0.75Ni-1Mn/1/2Co-Cr-A
Service
Universal trim for general service requiring long service life up to 593°C. As trim 5 for moderate pressure and more corrosive service. Steam, gas and general service to 540°C. Standard trim for gate valves.

I cannot tell a lie, I lifted this sometime ago. Shamelessly submitted without attribution.

RE: Gate Valve

The trim8 mean wedge sealing surface overlaying 13Cr, not the whole wedge 13Cr. Just like the seat ring stellite, not the whole seat stellite material.Moreover, casting material code of 13Cr is CA15.

Bruce | https://www.ntgdvalve.com

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