There are some valve manufactures that designed their
ball valve with double material seat and stem packing
to prevent leakage and blowout in fire case. They are
using reinforced TFE as outside material and grafoil
inside. It is very helpful.
- "SARE, RALPH H." <SARERH@YANPET.SABIC.com>
wrote:
> Advisory has been cirtculated related to the
> blow-out of the stem on ball
> valves. Look for the following features:
> Blowout proof stem to prevent stem removal while
> valve is installed.
> Stem grounded to the body to prevent lectrical
> discharge.
> Gear operatir for 10" and larger (those torque are
> really quite signifcatnt)
> Design that prevent overtunring of the ball.
>
> Do not use ball valve in open-ended service u nless
> it pass the seat leakgae
> firetest. Firetest to API 607 and purchase o spec
> to API 608 (prior to 608,
> we normally specify ball valve to MSS-SP-72 and
> B16.34).
>
> -----Original Message-----
> From: <a href="/group/PipingDesign/post?postID=pMuSin9fZRSlwgc9cSt1b1bJC7Ga8DB8E_OOwJX6oXt2HB9UkWrKh7Z-Gm2skm-bpoxoIQmO4pm5SrnZTW40PTE6Cma4zw">geoff.stone@lendlease.com.au</a>
> [mailto:geoff.stone@lendlease.com.au]
> Sent: 23 August, 2001 9:23 AM
> To: <a href="/group/PipingDesign/post?postID=egqHrlJoh7N3RUqJU6M4zHNwbxjjyil6JVzrkS0-31WNltDXjwp3mttreLMXG76KFJEFTGmK9szcyxzNL0DrKw5VL5wWymM">PipingDesign@yahoogroups.com</a>
> Subject: Re: [PipingDesign] Ball Valve
>
>
>
>
> Reduced port ball valves are used on an economic
> basis only. There are no
> advantages in this type of valve other than price.
>
> Full bore is used where you wish to pig the line or
> headloss is critical.
>
> Remember that there are other differences. There are
> trunnion mounted ball
> valves that are again more expensive. The benefits
> of this type of valve are
> that they are more robust as they have separate
> bearings and do not rely
> upon
> the seat to support the ball. Operating torque is
> lower and thus actuaor
> size
> can be smaller.
>
> The other difference is that ball valves can be
> general purpose or firesafe.
> The
> latter are used in the petro chem industry and are
> required to comply with
> BS
> 5351 and tested to BS 5146 ( the USA equivalent I
> think is API 6D). They
> have a
> metal seat as a reserve to the primary teflon seat.
> The teflon seat must be
> unreinforced so that in the vent of a fire the ball
> can seat on the metal
> reserve seat. If glass reinforced seat are used in
> the event of a fire there
> ii
> s no surety that the ball will seal on the metal
> seat.
>
> Another type of ball valve is the Orbit quater turn
> valve. This valve has a
> configuration where the ball moves away from the
> seat before it turns. This
> valve is used to stop wear on the seat when the
> fluid may contain sand and
> grit
> such as in the oil patch or on off shore rigs.
>
> For control applications there is the vee ported
> ball valve. This provides
> better control than a conventional ball valve. Used
> in the pulp and paper
> industry especially.
>
> .
>
>
>
>
> Rudiawan@Kvaerner.com on 23/08/2001 04:00:18 PM
>
> Please respond to <a href="/group/PipingDesign/post?postID=egqHrlJoh7N3RUqJU6M4zHNwbxjjyil6JVzrkS0-31WNltDXjwp3mttreLMXG76KFJEFTGmK9szcyxzNL0DrKw5VL5wWymM">PipingDesign@yahoogroups.com</a>
>
> To: <a href="/group/PipingDesign/post?postID=egqHrlJoh7N3RUqJU6M4zHNwbxjjyil6JVzrkS0-31WNltDXjwp3mttreLMXG76KFJEFTGmK9szcyxzNL0DrKw5VL5wWymM">PipingDesign@yahoogroups.com</a>
> cc:
> Subject: [PipingDesign] Ball Valve
>
>
> There two kinds of ball valve : Reduce bore and
> Full bore.
> Which is the specific condtions to use of each type
> ?
>
> Thanks
> rudiawan
>
>
>
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Received on Sun Aug 26 07:42:00 2001