Key points for installation and pipeline layout design of NORGREN solenoid valve

Key points for installation and pipeline layout design of NORGREN solenoid valve

NORGREN solenoid valve is a safety protection valve. The opening and closing parts of the safety valve are in a normally closed state under external force. When the pressure of the medium in the equipment or pipeline increases and exceeds the specified value, it automatically opens. It prevents the medium pressure in the pipeline or equipment from exceeding the specified value by discharging the medium outside the system. Safety valves belong to the category of automatic valves, mainly used in boilers, pressure vessels, and pipelines to control pressure beyond the specified value, playing an important protective role in personal safety and equipment operation.

The opening height of NORGREN solenoid valve disc can be divided into micro opening safety valve and full opening safety valve. The opening stroke height of micro opening safety valve is ≤ 0.05d0 (small discharge throat diameter); The opening height of the fully open safety valve is ≤ 0.25d0 (small discharge throat diameter).

NORGREN solenoid valves can be classified into three types based on their structural form: hammer type, lever type, spring type, and pilot type (pulse type); According to the structure of the valve body, it can be divided into two types: closed and non closed. A closed safety valve means that the discharged medium does not leak out and is completely discharged along the outlet to the location. It is generally used in toxic and corrosive media. Non enclosed safety valves are commonly used for NORGREN solenoid valves. The selection of safety valve products should be determined based on the actual sealing pressure. For spring type safety valves with several working pressure levels within a nominal pressure (PN) range, in addition to specifying the safety valve model, name, medium, and temperature, the valve body sealing pressure should also be indicated when ordering. Otherwise, the supply should be based on the maximum sealing pressure.

The installation and maintenance of safety valves should pay attention to the following: all types of safety valves should be installed vertically. The outlet of the safety valve should be unobstructed to avoid pressure. Before installation, safety valves should be specifically tested and their sealing properties checked. Regular inspections should be conducted on NORGREN solenoid valves in use.

(1) Safety valves on equipment or pipelines should generally be installed upright. But for safety valves installed at liquid pipelines, heat exchangers, or containers, they can be installed horizontally in places where pressure may increase due to thermal expansion when the valve is closed;

(2) The installation position of NORGREN solenoid valve should be as close as possible to the protected equipment or pipeline. If it cannot be arranged close, it is required that the pressure drop of the pipeline between the protected equipment pipe mouth and the safety valve inlet should not exceed 3% of the valve's rated pressure value.;

(3) NORGREN solenoid valves should not be installed at the dead end of long horizontal pipelines to prevent the accumulation of solid or liquid materials at the dead end, which may affect the normal operation of the safety valve;

(4) NORGREN solenoid valves should be installed in a location that is easy to maintain and adjust, with sufficient working space around them;

(5) Due to the heavy weight of large-diameter safety valves, it is necessary to consider the possibility of dismantling and hoisting them during layout, and if necessary, install suspension rods;

(6) The inlet pipeline of NORGREN solenoid valve should use a long radius elbow;

(7) The design of the outlet pipeline of NORGREN solenoid valve should consider a certain value of back pressure beyond the safety valve. For example, for a regular spring safety valve, its back pressure is less than 10% of the set value of the safety valve;

(8) The outlet pipeline of the safety valve discharged into the closed system should be diagonally connected at a 45 ° angle to the top of the pressure relief main pipe in the direction of the medium flow, in order to prevent the condensate in the main pipe from flowing back into the branch pipe and reduce the back pressure of the safety valve;

(9) The outlet pipe of NORGREN solenoid valve should not have a "bag shape". When the outlet pipe of safety valve is long, a certain slope should be set (except for dry gas system);

(10) When discharging the NORGREN solenoid valve into the atmosphere, it is important to note that the discharge outlet should not face equipment, platforms, ladders, or cables;

(11) There should be no "bag shaped" accumulation of liquid in the discharge pipe of the wet body pressure relief system, and the installation height of the safety valve should be higher than that of the pressure relief system. If the outlet of the safety valve is lower than the pressure relief main pipe or the discharge pipe needs to be raised and connected to the main pipe, a liquid separation package should be installed at a low point that is easily accessible;

1、 Leakage caused by detachment of the closure component

reason:

1. Poor operation can cause the closing component to get stuck or pass through the top dead center, resulting in damage and breakage of the connection;

2. The connection of the closure is not firm and loose;

3. Choosing the wrong material for the connectors cannot withstand the corrosion of the medium and mechanical wear.

Maintenance method:

1. Correct operation: Do not apply excessive force when closing the valve, do not exceed the top dead center when opening the valve, and after fully opening the valve, the handwheel should be slightly reversed;

2. The connection between the closing element and the valve stem should be firm, and there should be a stopper at the threaded connection;

3. The fasteners used to connect the closure and valve stem should withstand the corrosion of the medium and have certain mechanical strength and wear resistance.

2、 Leakage at the packing point (the proportion of valve leakage at the packing point is large)

Reason:

1. The selection of packing is incorrect, it is not resistant to the corrosion of the medium, and it is not resistant to the use of high pressure or vacuum, high temperature or low temperature in valves; 2. The packing installation is incorrect, with defects such as replacing large with small, poor spiral winding joints, and loose tightening and loosening;

3. The filler has expired, aged, and lost its elasticity

4. The valve stem has low precision and defects such as bending, corrosion, and wear

5. Insufficient number of packing rings, and the gland is not tightly pressed;

6. Damage to the gland, bolts, and other components makes it impossible to press the gland tightly;

7. Improper operation and excessive force;

8. The pressure cap is skewed, and the gap between the pressure cap and the valve stem is too small or too large, causing wear on the valve stem and damage to the packing.

NORGREN solenoid valve maintenance method:

1. The material and type of packing should be selected according to the working conditions;

2. Install the packing correctly according to relevant regulations. The packing should be placed and compressed one by one, and the joint should be at 30 ℃ or 45 ℃; 3. Fillers with long service life, aging, or damage should be replaced in a timely manner;

4. After the valve stem is bent or worn, it should be straightened and repaired, and those with serious damage should be replaced in a timely manner;

5. The packing should be installed according to the specified number of turns, the gland should be symmetrically and evenly tightened, and the compression sleeve should have a pre tightening gap of more than 5mm;

6. Damaged covers, bolts, and other components should be repaired or replaced in a timely manner;

7. The operating procedures should be followed, except for the impact handwheel, which should be operated with normal force at a constant speed;

8. The gland bolts should be tightened evenly and symmetrically. If the gap between the gland and the valve stem is too small, the gap should be appropriately increased; The gap between the gland and the valve stem is too large and should be replaced.

3、 Leakage of sealing surface

Reason:

1. The sealing surface is unevenly ground and cannot form a tight fit line;

2. The top center of the connection between the valve stem and the closing component is suspended, misaligned, or worn;

3. The valve stem is bent or improperly assembled, causing the closing component to be skewed or not aligned;

4. Improper selection of sealing surface material quality or failure to select valves according to working conditions