Knowledge of Safety Valve

What is a Safety Valve?

Safety valve is a valve that act as a protection of equipment from exploding or damaging and it is mainly installed in pressure vessels such as chemical plants, electric power boilers and gas storage tanks.
Safety Valve is a type of valve that automatically actuates when the pressure of inlet side of the valve increases to a predetermined pressure, to open the valve disc and discharge the fluid (steam or gas ) ; and when the pressure decreases to the prescribed value, to close the valve disc again. Safety valve is so-called a final safety device which controls the pressure and discharges certain amount of fluid by itself without any electric power support.
Safety valve support not only the safety of energy industry but also the safety and security of our life.title h3 product valve genri - Knowledge of Safety Valve

  1. “Nozzle” inside the Safety Valve starts to receive a higher pressure from the inlet side of the valve.
  2. When the pressure becomes higher than the set pressure, “Disc” starts to lift and discharge the fluid.
  3. When the pressure decreases until the predetermined pressure, the force of the spring closes “Disc”.

( Role of the spare parts )
Nozzle — Pressure Entrance 
Disc —– Lid
Spring — Pressure Controller

Components of the Safety Valve
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Parts of a typical safety valve

ASME standards which are suited in United States has referred to safety valve as a general term that pertains to different mechanisms that relieves pressures that are specifically designed in order to put off too much pressure build-up in the fluid contained inside. The term suggests its primary function which is to provide safety. It is vital that you know the parts of a valve so that in the event that you would use them, you will be able to utilize them at the maximum potential. The typical designs are consisted of a number of parts.

safety valve parts asme - Knowledge of Safety Valvesafety valve parts din - Knowledge of Safety Valve

The usual ones you can find are those with a spring inside. There are two fundamental parts of the typical design. They are the valve body which is positioned in a right angle and the valve inlet connection or what is commonly called a nozzle. The nozzle is often located above the system that holds the pressure. On the other hand, the outlet connection can be screwed so that it will be connected on the piped discharged system. In some cases, there would be no outlet connection when the bonnet is closed.

Meanwhile, the approach channel or the inlet tract can have a full-nozzle or semi-nozzle kind of design. This part is the only component of the safety valve, aside from the disc,that is open to the elements of the process when the operation is in normal mode. If the valve will be utilized for applications that include high pressure, it is recommended that you use full-nozzles particularly if the fluid is quite acidic. On the other hand, you can opt for semi-nozzles if you are not fond of replacing the inlet every time especially when it is the seat only that you ought to exchange.

On the other hand, the disc is positioned behind the nozzle seat by the spring, provided that it is in normal state of operations. This spring is lodged inside a bonnet positioned above the body. It may be open or closed depending on the application of the valve and what it contains. The discs in the pop types have a holder that plays a key role in the rapid opening feature of the valves. It is the spring that is responsible for the force that is pushed into the disc so that it can contract. More often than not, the springs used in safety devices are made out of carbon steel.

Spring adjuster is used in order to adjust the quantity of the compression given into the spring. It has the ability to regulate the pressure especially when the disc is moved from where it sits. The durability of all the above mentioned parts is usually covered in the Dresser Inc. safety valve reviews. No matter how good the valve you might have; if you do not know how you can make its parts work for your advantage, it will be of no value. Such safety devices are not cheap so you might as well maximize the budget.

title h3 product valve tokusei - Knowledge of Safety Valve

Spring-loaded Pressure-relief Valves

img product valve tokusei 01 - Knowledge of Safety Valve

Generally, the safety valves are referred to the Spring-loaded Pressure-relief valves, the most common type ( See the left figure ).
The load of the spring is designed to press the “Disc” against the inlet pressure.
Depending on the fluid type, such as steam, gas or liquid, we are offering a Bellows model to clear the back pressure effect.

Pilot-operated Pressure-relief Valves

img product valve tokusei 02 - Knowledge of Safety Valve

Pilot-operated Pressure-relief Valves are composed of Pilot Assy and Main Valve. Although Spring-loaded Pressure-relief valves adopts the force of the spring against the inlet pressure, the reliving pressure and reseating pressure of the Pilot-operated Pressure-relief Valves is controlled by Pilot Assy, which acts nearly as same as Spring-loaded Pressure-relief valves. There is no adjusting function in the Main Valve.
Pilot-operated Pressure-relief Valves have larger size variations compared to Spring-loaded type, which is applied in a severe condition such as high pressure.

Safety valve selection guide

There are quite a number of factors that you have to take into account when you choosing a safety valve.

The primary function of a safety valve is to protect not just properties but the lives of people dwelling in particular places as well. It is a safetymechanism that is intended to stop the fluid from flowing after the pressure normalizes. There are many different designs of valves that are available in the market. This is because each would differ slightly with their functions and applications. In addition, the designs vary because it also depends on the national standards where the valves are made. Since it performs a huge task of protecting everyone, it is of paramount importance that you know how to choose one.

safety valve selection - Knowledge of Safety Valve

There are quite a number of factors that you have to take into account when you choosing a valve. First is the disposal system type. Valves can have levers, open and closed bonnets. Those which have an easing lever allow the users to lift it manually. It is usually conducted during the maintenance period. ASME suggests that suck type of disposal can be used on 60°Cwater, air and steam. Meanwhile, open bonnets are applicable with non-toxic gases and with fluids which has temperature that is higher. Closed bonnet on the other hand is utilized when the fluid inside the container must be held by the valve.

Another thing to consider is the cost of safety valve. However, you ought to consider this greatly only when the application is quite important. After all, you are protecting your safety. Otherwise, you can opt for less expensive ones. The cost must be based both on the capacity and nominal size of the valve. Depending on the model, one may be very different from the other though it may bear quite similar inlet connection.

Furthermore, you must take into account the manufacturer of the valve that you are going to purchase. See to it that you will only buy from the leading firms so that you can ensure the effectiveness of the product and your security as well. Make sure that all parts of the safety valve are working well. Opt for firms that offer warranties so your interest will be protected.

One more factor that you must consider is the approval of the valve. There are many different standard codes that are intended for various models. It varies depending on how the product performs and on the materials used on its assembly. It ought to be approved by the concerned regulating bodies. This will help you put your mind at ease as you can guarantee that the product adheres to the standards set.

How to maintain a safety valve?

safety valve, as the term implies, is important to be maintained as it has the capability to prevent not just too much pressure but a catastrophic incident as well. As it concerns your very lives, it is of paramount importance that it is in good working condition all the time since inopportune events can come unannounced. They say prevention is better than cure. A good saying that can complement that old adage is one way of prevention is proper maintenance. Below are some useful tips on how you can safeguard your valve and keep it in top shape.

safety valve maintenance - Knowledge of Safety Valve

Writing down a checklist of all the things that need to be accomplished will be extremely helpful. This will allow you to list down all the tasks that ought to be carried out. Anticipate all the problems that may arise so that your entries will be complete. Keep in mind that maintenance is a serious matter and that you cannot afford to make a colossal blunder of forgetting something essential that could pose great risks for everyone’s safety.

It is also important that you set a certain schedule of repairing the valves. Normally, it is recommended that it must undergo repairs once or twice a year. However, depending on the present condition of thesafety device, the frequency of such efforts may be decreased or increased. You need to consider carefully when you will check valves there might be operations that can be affected.

The frequency of the maintenance efforts will also depend on the safety valve selection guidelines that you have adopted when you first set it up. The quality of the materials that you have purchase can have a direct effect on it. If the materials were newer, there would be lesser chances that it needs to be repaired. The manufacturer of the materials you have bought the valves from must be screened carefully.

Give your valves a thorough inspection once in a while. It pays a lot to have a good look on it every time so that you will not be surprised of the sudden damage. Watch out some distortions, leaks, or an unusual sound that it may produce. Such warning signs can give you an idea whether you will need to have them fixed right away. After you see what should be repaired, you must decide on who can do the job. If the problems are quite small, you can do it by yourself. However, if you deem that you will need professional help, do not hesitate to call one before the damage gets irreparable.

Source: China Safety Valve Manufacturer – Yaang Pipe Industry Co., Limited (

(Yaang Pipe Industry is a leading manufacturer and supplier of nickel alloy and stainless steel products, including Super Duplex Stainless Steel Flanges, Stainless Steel Flanges, Stainless Steel Pipe Fittings, Stainless Steel Pipe. Yaang products are widely used in Shipbuilding, Nuclear power, Marine engineering, Petroleum, Chemical, Mining, Sewage treatment, Natural gas and Pressure vessels and other industries.)

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Please notice that you might be interested in the other technical articles we’ve published:

  • How To Choose A Valve

  • Knowledge of a filter and a gate valve

  • What Are the Needle Valves

  • What are Thread Valves

  • What is a Butterfly Valve

  • What are Pipe Valves

  • Knowledge of globe valves

  • Knowledge of ball valves

  • Knowledge of Gate valves

  • Knowledge of industrial valves

  • Knowledge of Butterfly Valve

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