fluorine lined Archives

Precautions for the application of fluorine-lined valves

January 19, 2022

Appropriate selection and application of fluorine-lined anti-corrosion valves is a matter of concern to everyone in engineering. Tanghai Valve puts forward the following views based on years of field application experience for your reference. We are specialised in the production of fluorine lined butterfly valves.

lug butterfly valve-lined-PTFE-DI body (1)

The price of fluorine-lined butterfly valves is much lower than that of corrosion-resistant stainless steel valves and Hastelloy valves. Some metal valves with strong corrosive media cannot be used, but only plastic-lined valves can be used well. However, the plastic-lined valve must be suitable for application. It is hoped that several technical conditions such as application pressure and application temperature should be used. Take our company’s products as an example to illustrate the following:
(1) The temperature of the medium used in the fluorine-lined valve: Usually, the fluorine plastic used in the fluorine-lined valve is F46 (FEP), and the temperature of the medium used cannot exceed 150 °C (the medium temperature can reach 150 °C in a short time, and the temperature of the long-term use It should be around 120℃), otherwise, the F46 lining of various parts of the valve is easy to soften and deform, resulting in the valve not closing and the leakage is large.
If the temperature of the medium used by the user is below 180 °C for a short time and below 150 °C for a long time, another fluoroplastic, PFA, can be used, but the price of fluoroplastic lined with PFA is more expensive, so it should be used in advance when matching. Inquiry.
(2) Do not have negative pressure. Fluoroplastic-lined valves should avoid negative pressure in the pipelines used. If there is negative pressure, it is easy to cause the fluoroplastic-lined layer of the valve cavity to be sucked out (bulged) and shelled, resulting in failure of the valve to open and close.
(3) The pressure and differential pressure should be controlled within the allowable range. Especially the fluorine-plastic-lined regulating valve and globe valve sealed by bellows. Because the bellows is made of tetrafluoro material, the pressure is high and the pressure difference is high, which can easily lead to the rupture of the bellows.
Bellows-sealed fluoroplastic-lined regulating valve can be changed to PTFE packing seal if the operating condition pressure and differential pressure are high.
(4) The medium conditions used in the fluoroplastic valve should not have hard particles, crystallization, impurities, etc., so as to prevent the valve from breaking the valve core, the fluoroplastic layer of the valve seat or the tetrafluoro bellows during the opening and closing operation. For the medium with hard particles, crystals and impurities, when selecting, the valve core and valve seat can be changed to Hastelloy, but additional inquiry is required.

TH Valve is a professional manufacturer of butterfly valve, gate valve, check valve, globe valve, knife gate valve, ball valve with API, JIS, DIN standard, used in Oil, Gas, Marine industry, Water supply and drainage, fire fighting, shipbuilding, water treatment and other systems, with Nominal Diameter of DN50 to DN1200, NBR/EPDM/VITON, Certificates & Approvals: DNV-GL, Lloyds, DNV, BV, API, ABS, CCS. Standards: EN 593, API609, API6D

Video of PTFE butterfly valve:

What is a fluorine-lined valve? How to extend the service life of it?

January 4, 2022

Fluorine-lined valves are made by using PTFE resin (or profile processed) to be molded (or inlaid) on the inner wall of the steel or iron valve pressure part or the outer surface of the valve inner part, and use its The unique performance of the anti-corrosive medium valve is made into various types of valves and pressure vessels.

Fluorine lined butterfly valve-PTFE-WAFER (10)

Among anti-corrosion materials, polytetrafluoroethylene has incomparable excellent performance. In addition to molten metal, elemental fluorine and aromatic hydrocarbons, it is used in various concentrations of hydrochloric acid, sulfuric acid, nitric acid, aqua regia, organic acids, strong oxidants, and concentrated , Alternate dilute acid, alternate alkali, and various organic agents are all reacting spontaneously. The inner wall of the valve is lined with polytetrafluoroethylene, which not only overcomes the shortcomings of low strength of polytetrafluoroethylene material, but also solves the corrosion resistance of the valve theme material. Poor performance and high cost. In addition to its excellent chemical stability, PTFE has good antifouling, anti-sticking properties, extremely low dynamic and static friction coefficients, and good anti-friction and wet performance. Use it as a valve opening and closing sealing pair, and it is necessary to reduce the sealing surface The friction force between the valve and the operating torque of the valve is reduced, and the service life of the product is increased. The scope of its application can also be extended to the food and pharmaceutical industries.

Fluorine-lined valves are also known as anti-corrosion valves. They are often exposed to harsh working conditions. They are not toxic and harmful chemicals, or are very corrosive. Various acids and alkalis or organic solvents. Improper use will cause major economic losses and serious problems. as a result of. Correct use and maintenance of the valve can prolong the service life of the fluorine-lined valve. What details can be done to effectively protect it?
1. Before use, carefully read the fluorine-lined valve instruction manual.
2. Use according to the pressure, temperature, and use medium specified on the nameplate or in the manual.
3. When using, prevent the fluorine-lined valve from generating excessive pipeline stress due to temperature changes, minimize temperature changes, and add U-shaped expansion joints before and after the valve.
4. It is forbidden to use levers to open and close the fluorine-lined valve. Pay attention to the opening and closing indication position and limit device of the fluorine-lined valve. After opening and closing are in place, do not forcefully close it to avoid premature damage to the fluorine plastic sealing surface.
5. For some media that are unstable and easy to decompose (such as the decomposition of some media will cause volume expansion and abnormal pressure increase in working conditions), which will cause valve damage or leakage, measures should be taken to eliminate or limit the factors that cause unstable media to decompose . When selecting the valve type, the fluorine-lined valve with automatic pressure relief device should be selected in consideration of the changes in working conditions that may be caused by the unstable and easy decomposition of the medium.
6. For fluorine-lined valves on pipelines with toxic, flammable, explosive, and highly corrosive media, it is strictly forbidden to replace the packing under pressure. Although the fluorine-lined valve is designed to have an upper sealing function, it is not recommended to replace the packing under pressure.
7. For pipelines with spontaneous flammable media, measures must be taken to ensure that the ambient temperature and working condition temperature do not exceed the spontaneous ignition point of the media to prevent the danger caused by sunlight or external fire.

Applicable medium: various concentrations of acid-base salts and certain organic solvents.
Features: It is the most ideal anti-corrosion material in the world at present, and it has been widely used in the lining of large-scale rotary forming equipment and pipe fittings.

TH Valve is a professional manufacturer of butterfly valve, gate valve, check valve, globe valve, knife gate valve, ball valve with API, JIS, DIN standard, used in Oil, Gas, Marine industry, Water supply and drainage, fire fighting, shipbuilding, water treatment and other systems, with Nominal Diameter of DN50 to DN1200, NBR/EPDM/VITON, Certificates & Approvals: DNV-GL, Lloyds, DNV, BV, API, ABS, CCS. Standards: EN 593, API609, API6D

Video of PTFE butterfly valve:

Fluorine-lined valve instructions | Installation instructions

June 7, 2021

Fluorine-lined valve instructions | Installation instructions
1 The fluorine-lined valve flange cover cannot be opened at will. Unless it is ready to be connected to the pipeline, the PTFE flange surface may be bumped, scratched or deformed due to temperature differences and foreign objects, which may affect the sealing. If the cover is moved due to inspection needs, It is also necessary to quickly reset the cover plate after inspection to protect the PTFE flange surface.

Fluorine lined butterfly valve-PTFE-WAFER (9)

2 When the fluorine-lined valve is connected to the pipeline, the gasket is generally no longer used alone, but when it is connected with the flange surface of dissimilar materials (metal surface, etc.), appropriate gaskets should be used to protect the PTFE flange surface.
3 During the use of the fluorine-lined valve, if a leak occurs at a higher temperature, the system temperature should be lowered to room temperature first, and then the cause should be investigated and repaired.
4 During installation, the flange nuts should be evenly tightened in the diagonal direction (symmetrically), and matched with appropriate torque: a If the flange sealing surface leaks and the leak location nut is locked, the leak location nut should be loosened at this time Half a circle, and then apply the same torque to the opposite side to lock it again; b If the above method still does not stop the leakage, check whether the PTFE flange surface has unevenness, indentation, scratches, and then it can be leveled with fine gauze paper or cloth. reconnect.
5 It is not allowed to do any high temperature welding work on the fluorine-lined valve to avoid permanent damage to the lining layer.
6 Fluorine-lined valves should be stored in a dry and ventilated room. Stacking is strictly prohibited.
7 Fluorine-lined valves after maintenance must be tested and qualified according to relevant standards before they can be installed.
8 When manually operating the fluorine-lined valve, it is not allowed to force the valve to be opened or closed with the help of other levers.
9 When installing fluorine-lined valves with directional requirements, pay attention to the flow of the medium in the direction indicated by the arrow on the valve body, and ensure convenient operation and maintenance.
10 The sealing pair of fluorine-lined valves stored for a long time should be in a slightly separated state to avoid permanent deformation of the sealing surface under long-term pressure, which will affect the sealing performance and service life.

TH Valve is a professional manufacturer of butterfly valve, gate valve, check valve, globe valve, knife gate valve, ball valve with API, JIS, DIN standard, used in Oil, Gas, Marine industry, Water supply and drainage, fire fighting, shipbuilding, water treatment and other systems, with Nominal Diameter of DN50 to DN1200, NBR/EPDM/VITON, Certificates & Approvals: DNV-GL, Lloyds, DNV, BV, API, ABS, CCS. Standards: EN 593, API609, API6D

Classification and selection of fluorine-lined valves

September 16, 2020

Fluorine-lined valves, anti-corrosion valves, corrosion-resistant special valves

Introduction to fluorine-lined valves and corrosion-resistant valves:
Fluorine-lined valve, also known as fluorine-lined plastic corrosion-resistant valve, is a method of molding (or inlaying) polytetrafluoroethylene resin and placing it on the inner wall of the valve pressure part or the outer surface of the valve inner part. (The same method applies to all The lining of similar pressure vessels and pipeline accessories), using its unique performance in resisting strong corrosive media, is made into a special corrosion-resistant valve. Simply put, fluorine-lined valve is to use the lining process for all the places in the valve body that the medium can reach.

The lining material of fluorine-lined valves generally adopts FEP (F46) and PCTFE (F3) and other fluoroplastics,

double eccentric butterfly valve (6)

which can be applied to various concentrations of sulfuric acid, hydrochloric acid, hydrofluoric acid, aqua regia and various organic acids, strong acids, strong oxidants and others Corrosive media and other pipelines, but fluorine-lined valves are relatively limited by temperature, and are only suitable for media between -50°C and 150°C.

Classification of fluorine-lined valves and corrosion-resistant valves:
Common fluorine-lined plastic valves are: fluorine-lined butterfly valves, fluorine-lined ball valves, fluorine-lined globe valves, fluorine-lined diaphragm valves, fluorine-lined gate valves, fluorine-lined plug valves, etc.
1. Fluorine lined ball valve
The ball valve with fluoroplastic lining layer has extremely high chemical stability and is suitable for any strong corrosive chemical medium. The structure is a full-pass floating ball valve structure. The element leakage closes in the entire pressure range, which is convenient for the pipeline system to pass Ball sweep line and pipeline maintenance.
2. Fluorine-lined butterfly valve
Used in occasions requiring reliable sealing and good adjustment characteristics. The valve body of the fluorine-lined butterfly valve adopts a split type, and the sealing of the current end of the valve shaft is controlled by adding fluorine rubber to the rotating base surface between the butterfly plate and the valve seat, so as to achieve compact structure, beautiful appearance, reasonable process and reliable performance. The fluorine-lined butterfly valve ensures that the valve shaft does not contact the fluid medium in the cavity. It is very convenient to replace the valve shaft. The fluorine-lined butterfly valve can be completed without removing the pipeline.
3. Fluorine lined gate valve
One of the most common open-close valves, which use wedge-shaped gates sealed on both sides to connect or cut off the medium in the pipeline. The wedge gate valve does not allow a small amount of opening to be used as a throttling device in the pipeline to avoid high-speed flow The medium erodes and accelerates the damage of the sealing surface.
4. Fluorine-lined plug valve
The structure is compact and reasonable, the internal cavity space of the valve is minimal, and the medium retention is reduced. In addition, the special molding process makes the sealing surface dense, and the combination of herringbone ring PTFE packing enables the valve to achieve zero leakage; this series is for various It is designed for automatic opening and closing control of the pipeline of strong corrosive medium.
5. Fluorine-lined globe valve
The valve can be unblocked or blocked by lifting the valve flap. The valve flap and the inner side of the valve body are all made of fluoroplastic lining. It has the advantages of light switch, small size, reliable sealing, simple structure, convenient maintenance and wide range of use.
6. Fluorine-lined check valve
The fluorine-lined check valve only allows the medium to flow in one direction and prevents the flow in the opposite direction. Usually this fluorine-lined check valve works automatically. Under the pressure of one direction, the valve flap opens and the liquid flows in the opposite direction. There are liquid pressure and the weight of the valve flap, and the closing valve flap acts on the valve weight to cut off the flow. Fluorine-lined check valve includes lift check valve, swing check valve, wafer check valve and so on. H41F46 fluorine-lined check valve is suitable for various concentrations of aqua regia, sulfuric acid, hydrochloric acid, hydrofluoric acid and various organic acids, strong acids, and strong oxidants at -50℃～150℃. FEP is also suitable for various concentrations of strong alkali Use on pipelines of organic solvents and other corrosive gases and liquid media.

Posts

Precautions for the application of fluorine-lined valves

What is a fluorine-lined valve? How to extend the service life of it?

Fluorine-lined valve instructions | Installation instructions

Classification and selection of fluorine-lined valves

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