Güvenlik açısından kritik uygulamalarda doğrulanabilir ve sürdürülebilir kapatma ihtiyacı ile birlikte, sistem bütünlüğünü sağlamak amacıyla birincil ve ikincil sıkı kapatma için DB&B Vanalar yaygın olarak kullanılmaktadır.

DB&B vanaların uygulama alanları nedir?

DBB vanası, kimyasal uygulamalarda , manometre baglantilarinda , Petrokimyada ile Petrol& Gas Sektörlerinde uygulama alanlari bulur . DB&B vanaları çok daha az ağırlık ve alana ihtiyaç duyar, ancak üç farklı vananın işini yapabilir, yani iki izolasyon vanası ve bir tahliye vanası. Genel olarak bu vanalarin ne zaman kullanilmasi gerektiği ile ilgili kafa karisikligi oluşabilir , Temel olarak bu vanalar iki izolasyon yöntemi arasında bir havalandırma/Bosaltma valfi gerektiğinde ve yüksek sizdirmazlik istendiğinde kullanılır.

DB&B Vanaların kullanım avantajları nedir?

DB&B vanasi, geleneksel bağlantıya göre ek avantaj elde etmenizi sağlar. İki küre arasında bulunan boşluk çok küçüktür, bu da bir operatörün alanı oldukça verimli bir şekilde boşaltabileceği ve dolayısıyla çalışması kesinlikle güvenli bir ortam oluşturabileceği anlamına gelir.Kisaca iki vananın yapacagi faydayı tek bir vana ile elde etmenizi saglar .

DB&B Floating Küresel vana ile DB&B Trunnion küresel vana arasındaki fark nedir?

Trunnion küresel vana, küreyi üstte ve altta sabitlemek için mekanik bir araca sahiptir, bu tasarım, daha büyük ve daha yüksek basınç vanalarına uygulanan standart tasarımdır. Floating yani yüzer tip Küresel Vanada ise basınçla birlikte küre hareket eder ve çok yüksek basınçlar icin uygun degildir .

Double Block and Bleed (DBB) Ball Valves

Anasayfa » Double Block and Bleed (DBB) Ball Valves

Ingredients :	Steel, Stainless Steel, Monel, Hastelloy, Duplex, Super Duplex, Other
Connection :	Flanged, Welded
Drive Unit :	Manual, Electric, Pneumatic, Hydraulic
Temperature :	(-200 °C) – (+550 °C)
Nominal Diameter :	3/4″ – 24″
Rated Pressure:	Class 150 – 2500

DOUBLE BALL / DB&B PLUG VALVES

With the need for verifiable and sustainable shut-off in safety critical applications, DB&B Valves are widely used for primary and secondary tight shut-off to ensure system integrity. Historically when mastered, system integrity can be achieved by using a spool piece and a relief valve with two separate shutoffs (such as Ball, Plug valves ….) which has extensive cost problem and weight disadvantages and also increases the risk of emissions from multiple flanged surfaces. As a result, combined integrated DB&B valves are now widely used. These valves have a double Ball or Plug valve; single or side entry body design with a relief valve mounted between two main line valves. These valves are available in bi-directional metal seated and soft sealed style with leak tight shut off. DB&B valves, sometimes called twin valves, are available in Double Block and Bleed (DB&B) type up to 600 mm NB in ANSI class 150 to 2500. These DB&B design valves replace existing conventional techniques used by pipeline engineers to create a double block and bleed configuration in the pipeline. The various designs and configurations of Double Block and Bleed valves are as follows:

SINGLE SPHERICAL TRUNNION DB&B

Conventional single ball trunnion mounted ball valves have two acting, usually bi-directional seats. A relief valve may be installed in the body cavity at the discharge point to allow later verification of seat integrity, and this type of valve is then referred to as a “Double Block and Bleed Valve” (DBB). Pipeline Valve, each valve is individually tested to verify zero leakage at the discharge point. Conventional single globe trunnion valves typically have self relieving “single seal” seats that automatically relieve stem cavity pressure downstream. One-way valves that relieve only upstream can be specified. The traditional single ball design allows a closed valve to leak upstream or downstream if the body cavity is over-pressurized. Double piston acting (DPE) seats can be specified as single ball DB&B Trunnion valves. This type of valve is classified as a “Double Isolation and Bleed valve” (DIB) in API6D. This design ensures that both seats are always sealed, even if one seat fails, the other seat will continue to provide the seal as the other seat provides a two-way seal. With DPE sites, a body cavity external pressure relief valve is fitted (this can optionally pass to the upstream flange of the valve or to the expansion). This is a cheaper option than double globe DB&B valves and also provides a high level of integrity.

DBB Valves

What is Double Block and Bleed?

The DBB valve is a single valve consisting of two site faces. It can seal against pressure from both valve ends when the valve is closed. The main operating characteristic of this valve is that it discharges fluid or exhausts air between the seat faces. The DBB Valve is designed to avoid the need to bolt individual valves. A single valve can provide double sealing reducing the cost by over 60%.

Design

There are two block valves that function as manifolds or uni, as well as a relief valve. This assembly is installed to provide a positive isolation. Double block and bleed valves are used for hazardous or toxic liquid processes or high pressure systems and many more critical processes. These valves can have a pressure range, usually 10,000 psig, and a temperature range, usually -70.6°F to +1,002°F.

Implementation:

Double DBB valves find applications in chemical applications, manometer connections, Petrochemical and Oil & Gas Industries. DB&B valves require much less weight and space, but can do the work of three different valves, i.e. two isolation valves and one relief valve. In general there can be confusion about when these valves should be used, Basically these valves are used when a vent/drain valve is required between two isolation methods and high tightness is required.

Study:

DB&B valves are used to provide positive isolation when processes are active in the plant and when maintenance activities are performed. Positive isolation can be achieved during shutdown, maintenance or repair activities. Initially, both valves are closed. Then, the shutdown side is vented to prepare for maintenance. The process fluid trapped in the space between the two block valves is discharged by the relief valve assembly. In this way, the shutdown side is separated from the process fluids by means of isolation valves.

DB&B Valve Additional Advantage

The DB&B valve gives you an additional advantage over the traditional connection. The space between the two spheres is very small, which means that an operator can evacuate the space very efficiently, thus creating an environment that is absolutely safe to work in.

DB&B Valves – FLOATING TYPE

The design of ball valves is based on the “floating Ball” principle, which allows the ball to rotate freely between the seals. A positive seal is achieved by the fluid pressure acting on the upstream surface of the ball and the downstream pressure creates a constant homogeneous contact between the sphere and the seal, ensuring a tight seal. The sphere is actuated by a closed shaft with a protruding square end to which the joystick or optionally the actuator is attached. Ball valves are intended for use as on/off flow control devices and should not be used to throttle fluid flow. Valves must always be fully open or fully closed.

DOUBLE BLOCK & BLEED – TRUNNION TYPE

The trunnion ball valve has a mechanical means to fix the sphere at the top and bottom, this design is the standard design applied to larger and higher pressure valves. Sealing is provided by spring-loaded piston-type seats which shut off the flow when line pressure acts on the upstream seat. In the case of self relieving seats, the Trunnion design provides automatic relief of cavity overpressure. The ball operation is supported by a sealed stem connected to the operator. Ball valves are designed for use as on/off flow control devices and should not be used to throttle fluid flow. Valves must be fully open or closed at all times.

BENEFITS OF DB&B Valve Design

ENHANCED SECURITY IN OPERATIONS
SPACE, WEIGHT AND COST SAVINGS
REDUCED SEALING POINTS
REDUCED INSTALLATION AND MAINTENANCE REQUIREMENTS AND COSTS
COMPACT DESIGN
UNINTERRUPTED FLOW FOR NEGLIGIBLE PRESSURE DROP
REDUCED VOLTAGES FROM LOADING AND VIBRATION
SPECIAL CASE DESIGNED AND ENGINEERED

Frequently Asked Questions

What is DB&B Valve?

With the need for verifiable and sustainable shutdown in safety-critical applications, DB&B Valves are widely used for primary and secondary tight shutdown to ensure system integrity.

What are the application areas of DB&B valves?

The DBB valve finds application in chemical applications, manometer connections, Petrochemical and Oil & Gas Industries. DB&B valves require much less weight and space, but can do the work of three different valves, i.e. two isolation valves and one relief valve. In general there can be confusion about when these valves should be used, Basically these valves are used when a vent/drain valve is required between two isolation methods and high tightness is required.

What are the advantages of using DB&B Valves?

The DB&B valve gives you an additional advantage over the traditional connection. The space between the two spheres is very small, which means that an operator can empty the space very efficiently and therefore create an environment that is absolutely safe to work in. In short, it allows you to get the benefit of two valves with a single valve.

What is the difference between DB&B Floating Ball valve and DB&B Trunnion ball valve?

Trunnion ball valve has a mechanical means to fix the sphere at the top and bottom, this design is the standard design applied to larger and higher pressure valves. In Floating type Ball Valve, the sphere moves with the pressure and is not suitable for very high pressures.