difference between short pattern and long pattern in valves

Ball Valve

Ball valves usually function as block valves or isolation valves to fully shut off or fully open flow. It is suited for conditions where quick on/off and /or bubble tight service is required.

Note:

1. Soft seated ball valves shall not be used welded because the welding heat will damage the seat.

2. Soft seated ball valves have lower pressure/temperature ratings as compared to same class metal seated ball valves.

3. Soft seated ball valves shall not be used for throttling service because the soft seat might be damaged due to erosion during the throttling operation.

Types of Body

a.
Multi-piece Body: As shown below, this design is easy to maintain, but it is generally recommended for utility services. In order to use this for hydrocarbon service, the design must be certified for "firesafe".

b. One-piece Body: There are three basic one-piece designs: the end entry, top entry and sealed (welded) designs. The top entry design is a preferred design due to ease of inline maintenance.

Types of Seat Rings

a. Metal to Metal: These are generally not bubble tight and are used for temperature over 400F.

b. Soft Seat (Metallic Seat Ring): The metallic seat ring, containing nonmetallic insert, usually requires spring force to achieve tight seal. Due to springs, this design is not used in corrosive service.

c. Soft Seat (Nonmetallic Seat Ring): The nonmetallic seat ring is made from e.g. Teflon. The ring is held against the ball by an insert. For firesafe service, a secondary metal to metal seating arrangement is required to omit leakage in the event that the soft seat material is lost during a fire. This is done by adding a metal retention lip as shown in figure.

Ball Supports

a. Seat Supported: In this design the ball is supported by the seat rings. The seat rings are fixed in the body and the ball is free to move. Therefore, only one seat seals at a time and the valve can not be considered a " double block and bleed" type. This type of valve is used for sizes smaller than 6".

b.Trunnion Supported: In this type the seats are spring loaded and floating while the ball's position is fixed. The valve is capable of sealing from both sides, and is therefore also called block and bleed type valve. All ball valves 6" and larger in Classes 150 and 300, and all sizes in Class 600 and higher shall be this type.

Mr fulan... thanks for the additional info... but that doesnt answer my question. I wanted to know the differnce betwween shor pattern and long pattern in valves and their applications. Patterns are different with repect to their face to face dimensions..

When ball valves first came into the market, they competed against gate valves. So the end to end dimensions are those of old gate valves, and not what is really ideal for ball valves. What the manufacturers do is select the shortest possible length from the available sizes in which they can fit the ball, seats, flanges, assembly of the flange and any body bolting. This will be what they sell in high volume. Lengths that are longer are not need to build or install the valve, so they are less common, harder to find, and are more expensive.

Because of this history, there is no standard length based on valve size, port size, pressure class, etc. It is going to vary by manufacturer depending upon the size, port diameter, seat type, floating ball or trunion, etc. As mentioned above, items that require a longer body length to fit all the parts are where you will find long body lengths. Items like, full port, trunions, spring loaded seats, etc. All the expensive stuff that you should not use unless you really need to.

SMS

Assuming that you are asking about Butterfly short & Long Pattern design:

1. Short pattern valve: Distance between end to end flange is shorter (so called short pattern). And designed as per ISO 5752 standard.

2. Long pattern valve: Distance between end to end flange is wider (so called long pattern). And designed as per API 600 standard.

DIFF: Diff between both pattern is not only end to end distance but the standard according to which valve is designed.

Answer is: API 600 standard has been using for Gate valve. Now if any one want to replace existing gate valve with new butterfly without changing the piping orientation then he should ask for Long pattern butterfly valve. Which has been designed using same API 600 standard. So 4" size of gate valve and 4" of long pattern butterfly valve both end to end distance is same and easily fit in into existing pipe lines.

Result of replacement: Low cost valve, No orientation change in existing pipes and achieve same function of (on-off application).

I hope above is as per what you are looking for.......

<...someone...>

There are about 83,000,000 pages on the internet about this, according to Mr. Bing.