Engineering

Valve Positioner is one of the most extensively used control valve accessories in different industries.

To regulate the rate of gas and liquid flow, a large number of valves are used in oil and chemical plants as well as food, pharmaceutical, steel plants. Each valve is associated with a positioner that controls the valve’s position according to the command from the control system.

What is a Valve Positioner?

Valve Positioner is a device installed with a control valve to get precise and rapid control over flow, to reduce frictional effect and steady valve position even with fluctuating pressure.

Valve Positioner, Image Source: cascadeautomation

The use of a Valve Positioner with a control valve is essential to get accurate and quick control without any hysteresis. The controller sends a direct input signal to the Positioner instead of the actuator. The control signal applied to the Positioner operates the actuator stem through a flapper nozzle mechanism.

Valve Positioner, Image Source: chemicalengineeringworld

Valves are a vital part of any industry that is installed on pipes to control the flow rate of gases and liquids. Hundreds and thousands of valves are required as per the capacity of a plant. Proper control of opening and closing and adjustment of degree of opening of these valves is essential. To get the correct stem or shaft position as set by the control system, Valve Positioners are used widely so that depending on the input from the controller, it can adjust the air pressure to the actuator diaphragm to maintain the correct stem position of the valve.

Where is a Valve Positioner located?

Valve positioners are installed with a control valve to regulate the position of a valve depending on the predecided data for a process variable which may be flow, pressure, or temperature.

As per the type of Valve actuator, the position of Valve Positioner is determined. Normally, the location of a Positioner in case of pneumatic type actuator for a linear control valve is yolk or top casing. In a rotary control valve, the Positioner is located close to the end of the shaft.

Whether rotary or linear, in either types of control valve, the positioner sits and travels along with the valve stem. It measures the distance travel in case of linear valve and degree of rotation for rotary valves and controls the valve as per the points set by the controller.

Location Of a valve Positioner, Image Source: instrumentationtools

What is the necessity of a Valve Positioner?

Valve Positioner helps a control valve to respond quickly as per the changes of the process variable. They are advantageous for a system where fluctuations are the main obstacles to efficiency and quality.

The necessities of a Valve Positioner are explained below:

• Speed: Valve Positioner minimizes the response time of the system, whether operating above or below the set point
• Accuracy: A Positioner gives better resolution and more precision than an actuator can provide on its own. Controller send input signal directly to Valve Positioner. The feedback mechanism provided in the positioner allows to cross-check the valve position and readjust air requirement/pressure to reposition the stem as per the signal provided by the controller. Reduction in friction: Reduces friction effect of valve stem packing, especially beneficial for high-temperature packing material like graphite.
• Range: Valve Positioners also help to control a wide throttling range.
• Split Ranging: Using a Valve Positioner, we can use two valves with one controller(4-12 mA and 12-20mA) without any error.
• Seating friction: Help to defeat seating friction in case of a rotary valve.
• Increased flexibility: By using a Valve Positioner actuator is enable to face high apparatus air supply pressure.
• Flexible configuration: Utilization of a Positioner removes the limitation on distance between the controller and the control valve as the control signal can be sent electronically and converted to pneumatic signal at the input point of the Positioner. On the other hand if an actuator is operated pneumatically over long distance, the control becomes erratic.

Valve Positioner types

A Valve Positioner can receive or transmit both electrical as well as pneumatic signal. The classification of Valve Positioner is based on type of signal it can receive and transmit or a combination of both. 

Different types of Valve Positioners are:

• Pneumatic Valve Positioner:  This type of Positioner get pneumatic signal from controller and they also transmit pneumatic signal to the actuator. They provide a high air pressure to change the position of the actuator and are quite safe for use.
• Electric valve positioners: They transmit and accept electrical signals.
• Electro-pneumatic valve positioners: Also known as “Analog Positioner” because the electrical input received are in the form of analog signals. An electrical signal is fed from the controller but in return Positioner deliver a corresponding pneumatic signal to the pneumatic valve actuator.
• Digital or “smart” valve positioners: Popularly known as “Smart Valve Positioners.” This type of Positioner uses a microprocessor to control the valve actuator and record and monitor data. The electrical input is in the form of a digital signal, and the corresponding output is a pneumatic signal.

Valve Positioner working principle

A pneumatic Valve Positioner is a mechanical device employed to fine-tune the movement of the stem of a control valve.

The pneumatic Positioner is provided with a feedback mechanism to accurately identify the control valve stem position and compares it with the input signal. Based on the feedback signal, the positioner varies the supply of air to the actuator stem in order to bring the stem into the position dictated by the signal sent to the Positioner from the controller. 

There are two philosophies on how a positioner is implemented. One is where the air is used to opena valve stem, and the other is when to air the used to close a valve stem. The description of the mechanism noted below is for the second case, i.e., the air is used for closing a valve stem. This is also called a direct-acting Valve Positioner.

Direct Acting Valve Positioner, Image Credit: instrumentationtools

The Positioner is normally fitted into the yolk or pillars of the actuator. It is operated by an input air pressure of 3-15 psi (0.2 bar to 1.1 bar); as the signal is provided from the controller to open the valve stem, the input air pressure to the input instrument increases. The input pressure acts on the input signal diaphragm, which drives the diaphragm along with the flapper connecting stem. The flapper connecting stem opens the supply flapper allowing the supply air to act on the actuator stem diaphragm.

During this time, the exhaust flapper is in the closed position as the flapper connecting stem is deflected to the right. As the air pressure is increased, it forces the valve stem down. As shown in the figure above, the positioner lever moves clockwise as the valve stem goes down.

Due to this clockwise rotation of positioner lever, range spring experiences a compression through cam. As soon as the valve stem reaches the position as per the set point provided by the controller the range spring exerts a balancing force closing both the exhaust and supply flapper and the desired control action is achieved.

On the other hand, if the controller sends a signal to open the valve, the signal pressure decreases. With the decrease in signal pressure, the force from the range spring push the flapper linking stem towards left direction. As a result, the exhaust flapper is opened. The force acting on the actuator diaphragm also decreases causing a upward movement of the valve stem until an equilibrium in force balance is achieved.

The device used for regulating the flow of fluids in passage ways are called as valves. This article tells us about what are valves uses and related insights.

• Gate valves
• Globe valves
• Butterfly valves
• Ball valves
• Check valves

Application of valve in industry

Industries use many types of valves which include gate valves, ball valves, globe valves, butterfly valves and check valves. 

The applications of above mentioned valves are given below-

• Gate valves– They are used in high temperature and pressure conditions. They are used for binary operations such as ON/OFF. They can be used in both directions inside a flow circuit. They operate on low friction and can be used both ways.

• Globe valves– They are generally used for throttling purposes. These valves are used as stop check valves as their opening and closing time is much shorter than other valves. The body ring seating surface is easier in globe valves.

• Ball valves– These valves are used to regulate the flow of corrosive fluids and slurry and are also used in oil industry. They provide leak proof service.  They are compact and requires little or no lubrication.

• Butterfly valves– These valves are used in pharmaceutical, chemical and food processing services. They are used for low pressure and low temperature applications. They can be installed without pipe dislocation. They are very reliable and require little or low maintenance.

• Check valves– They are used in waste water management and in industries such as refining, petrochemical, chemical, viscous fluids etc. These valves prevent backflow and serve as backup system. They sustain high pressure which helps in preventing the backflow.

What is a valve?

As mentioned above, valve is a device that is used for regulating or controlling the flow of fluids by opening or closing passage ways.

By opening or closing passage ways, valves create obstruction (or remove obstruction) from the fluid flow which enables the flow to stop or continue (if it was being stopped initially). The amount of closing and opening can control the speed and discharge of the flow.

Image credits: Paul Goyette, Water valves with spigots, CC BY-SA 2.0

Working mechanism of a simple valve

Valves can be used to regulate or control the flow of fluid. That means it can start/stop the flow as well as control the discharge of the flow as well.

If a valve wants to stop the flow, it will simply close the entire cross section of the passage. To control the discharge, it will partially close the cross section so the flow will occur only through a small portion of the passage.

Variation of sizes in valves

Depending upon the application, valves can vary in size.

The size of a valve is typically in the range of 0.1mm to 60cm. Although there are special valves which have diameters exceeding 5m. They can be cheap (simple disposable valves) and of very high cost that are used for special purposes.

Types of valves

Valves can be classified on many basis. To make it simple, we classify them on the basis of their mode of actuation.

Different types of valves used in industries are-

• Hydraulic– Hydraulic valves are used to control the fluid flow in a hydraulic circuit. This is done by controlling pressure and flow rate of flowing fluid and are actuated by action of a hydraulic fluid.
• Pneumatic- Pneumatic valves are used to control or regulate the flow of air or any other inert gas. These valves are actuated with the help of pressurized gas.  
• Manual– Manual valves are simply those valves which needs to be actuated by a manual operator.
• Solenoid valve– These are control units which disrupts the flow of fluid when energized or de-energized.
• Motor valve- Motors are used to actuate the valve. These are used in pumps.

Components of valve

A simple valve comprises of two main parts- Body and bonnet. Both of them form a casing that is responsible for holding the fluid that goes through the valve.

• Body-As the name suggests, body is the outer casing of the entire valve that contains internal parts.
• Bonnet-Bonnet is the covering of the valve. It may be semi-permanently screwed to the valve body or simply bolted onto it. Stem passes through bonnet that acts as seal of the valve.
• Ports-These are small passages that allows the fluid to pass through the valve.
• Handle or actuator-It is used to control the action of valve manually. With the help of this, the valve can be closed or open as and when needed. The movement of actuator can be automated by the use of sensors and electric circuit.
• Disc-It is an internal part in the valve assembly which adjustably obstructs the flow of the fluid inside the valve.
• Seat-It is the inside surface of the body that comes into contact with disc to make a leak-tight seal.
• Stem-It is responsible for transferring motion from the handle to disc.
• Valve balls-These are used for high pressure and heavy duty applications. They are generally made of Titanium and stainless steel and sometimes plastics such as ABS, PVC or PVDF.
• Spring-Some valves have spring for spring loading to set the position of disc and reposition it as and when needed.

What is trim in valve?

Trim simply refers to the internal parts of the valve assembly or internal elements of valve.  

According to API standards, trim contains disc, stem, valve balls, spring, seating surface in the body gate, gate seating surface, bushing, stem hold guide and small internal parts that contact the service fluid.

What valve operating positions of valves?

Valve operating positions are the operating conditions based on the position of disc inside the valve.

• Two port valves– For two port valves, the operating positions can be completely shut or completely open and sometimes partially open to precisely control the degree of flow.
• Three port valves– These kind of valves serve many functions. Some of them are used as shuttle valves, thermostatic valves, single handler mixer valves etc.
• Four port valves- It has four equally spaced ports round the body. It can be operated in two positions. This kind of valve is used to simultaneously isolate and bypass a sampling cylinder that is installed on a pressure line.

Limit Switch valves have wide use in our daily life at home as well as in our workplace.

A simple example of the application of Limit Switch is the light comes on inside the fridge whenever we open the fridge door. Here Limit Switch detects if the fridge door is opened or closed.

Another most frequently seen use of Limit Switch is in the overhead shop and garage doors where Limit Switch stops the movement of the door at its fully opened position.

What is a Limit Switch valve?

In an automatically operated machine, Limit Switches are used to convert the mechanical movement of the device into an electrical signal.

As per its name ‘Limit,’ these switches mainly define the limit or boundary of travel of an object or machinery. At the same time, these electromechanical devices indicate the presence or absence of an object.

After getting physical indications, it is easy to operate the whole circuit by converting mechanical motion into an electrical signal.

Limit Switch, Image Source: Automation forum

What is the function of Limit Switch?

Limit Switches are activated by the presence or absence of an object or by the movement of machinery.

The primary function of a Limit Switch is to open or close a contact in a circuit when a certain distance covered by a motor-operated device has been reached. Limit Switch is applied in the control circuit for different purposes like slow down, reverse, or stopping the operation of the machinery.

A Limit Switch consists of an actuator connected to an electrical switch. As soon as a moving machine or a moving machine part strikes the actuator, the operation of the Limit Switch begins and actuates the switch. As a result, the Electrical circuit controls the machine and its motion.

Limit Switches can be used either as a control device for standard operations or as emergency switches to stop the inappropriate functioning of the machine.

Components of a Limit Switch

A Limit Switch is a detection kind of switch inside a metal or resin casing. The outer case is necessary to protect the switch from dust, dirt, external forces, moisture, oil, etc.

The main components of Limit Switch are:

• Actuator: This is the part that comes in physical contact with the moving machine or machine part. It is constructed with tough material to withstand a significant amount of force and shock.
• Operating head: Sometimes, the actuator is connected with an operating head which converts the rotary, linear, or perpendicular motion of the device into an electrical signal to operate the switch.
• Switch body: It refers to the whole electrical contact mechanism.
• A series of Electrical terminals: Screws or screw/clamp assembly essential for wiring purposes.

Components of a Limit Switch, Image Source: @pub/@electrical

What triggers a Limit Switch?

Limit switches are triggered by a physical force applied to the actuator of the switch by machinery. The cams connected to the actuator shaft readily activate the switch.

When the product comes to physical contact with the actuator of a Limit Switch, this physical touch is converted into an electrical signal which activates or deactivates the electrical circuit within the switch. As the product moves away, the actuator and the switch go back to the normal position.

Different types of actuators are used in Limit Switches depending on different applications. Actuators are mainly selected considering certain factors like travel distance, shape, speed, the direction of the machine part being used to trip the Limit Switch. The main types of actuators are flexible rod, plunger, and roller lever.

Function of a Limit Switch, Image Source: omron.com

What is a valve position switch?

Valve position switches are electrical switching devices associated with a Limit Switch for giving an easy visual indication of the current position of the valve assembly.

Valve position switches inform us about the position(open, closed or in an intermediate state) of the valve in the form of continuous signal. These switches can be fixed directly on the actuator of the valve. They can be used in combination with a valve positioner.

Limit switches are activated by the physical touch experienced by the actuator of machinery. The mechanical motion experienced by the actuator plunger is converted into electrical signals which in turn change or regulate the make or break state of the circuit.

Valve position switch, Image credit : aoxactuator.com

How does a Rotary Limit switch work?

Rotary Limit Switches are generally used to control shaft revolutions or to limit movement based on the rotation angle of industrial machinery.

A Rotary Limit Switch is an assembly of gears and cams to trigger a microswitch when the preset number of revolutions has been reached. Here the working principle of a worm drive has been followed. Gears are linked to a cam mechanism that rotates entirely depending on the central gear.

In a Rotary Limit Switch, a shaft must turn a predetermined number of revolutions before the contact changes state as in cranes.

Rotary Limit Switch consists of a shaft that is connected to the shaft of a gear box through a coupling. When the shaft of the gear box rotates, the shaft of the Rotary Limit Switch also rotates. Cams are mounted concentrically with the gears, so as the gears turn, the cams rotate, and rocker arms attached to the cam lobes trip switches at set positions.

Rotary Limit Switch, Image Source: Motion control tips

Generally the input gear is a worm gear but planetary and spur gear are also used. Gear type is decided depending on the requisite gear ratio. The limit at which the switches are activated depends on design of cam lobes and on the ratio of the input gear.

Rotary Limit Switch, Image Source: ohmic-local-manufacture

At least two cams and two switches are essential for a Rotary limit Switch assembly, one for each end or upper and lower limit of travel of the machinery.

Frequently Asked Questions (FAQs)

Q.What are the applications of a Limit Switch?

Ans: Though Limit Switches are available in many forms and perform different functions but in general they are electromechanical switches which are operated by the presence or motion of an object.

Some applications of Limit Switches are as follows:

• In material handling application giving indication of passage of material from one platform to another.
• Widely used in overhead cranes
• Used in automatic machinery.
• Used in High speed equipment.
• Also used in machine tools and rusticate the travel of a machine axis.
• Used to control the liquid level in pumping system.
• Used in elevators and conveyors.

Q. What are the types of Limit Switches?

Ans: Limit switches are classified based on motion of the lever and type of actuating mechanism.

Limit switches are classified based on the actuating mechanism as:- Lever type and Plunger type. Based on the type of motion the limit switches are classified as Rotary motion type and Linear motion type.

Lever Type: A switch with lever type actuating mechanism has a lever attached to it. When the moving machinery or equipment comes in contact with the lever it pushes the lever, which in turns connects or disconnects the electrical circuit. The contact point of the lever with the machinery is normally provided with a roller. The lever is also provided with a retrace mechanism to bring back the lever to original position once the machinery/ equipment is removed from the position. It normally finds use in lifting cranes, lifts etc.

Plunger Type: A Push or plunger type Limit switch on the other hand, gets actuated when the machinery or equipment presses against the push button provided in the limit switch. This is the most common type of limit switch which are available in a car or a refrigerator door. A typical push type limit switch is shown below.

Rotary Motion Limit Switch: A rotary motion limit switch is normally attached to a rotating device such as an electric motor. It detects the rotary motion of the shaft or device connected to it. On achieving specified number of rotations or in other cases angles set for rotation, the limit switch gets activated. They are normally used for rotating service such as crane hoisting or in service where linear motion is translated to rotating motion.

Linear Motion Limit Switch: The most common type of limit switch used in the industrial application is the linear motion limit switch. They detect the linear motion of the equipment or machinery and find wide sue in packaging, manufacturing, motor control and other consumer applications.

Gate valves are generally made for shut-off, and you find them in almost all plumbing applications from industrial to water supply at home or in gardens.

Needless to say, the same applies for home fluid plumbing as well. To solder a Gate valve following steps are to be followed:

• For smooth functioning and cost-effectiveness of the fluid pipelines, proper soldering of a Gate Valve is mandatory.
• Ensure that the whole piping system is free of any fluid(or water in case of home plumbing) by closing the main valve and draining the residual fluid.
• Before you start the soldering job, ensure the valve is in close condition.
• Measure the length of the Gate valve accurately because that much portion of the pipe has to be cut (generally ½ to ¾ inch depending upon the size of the valve and piping)
• Next, using a pipe cleaner, clean the main pipe as well as the Gate valve. The ends of the pipe must be free of dirt. Cleaning the inside of the pipes is as important.
• Using a flux brush apply some paste flux on both the ends of the main pipe and along with the Gate valve.
• Now insert the cut ends of the main pipe inside the Gate valve properly. Some resistance should be expected.
• For the final step, get the solder wires. Using a propane torch heat both the ends to be soldered. Keep the bent end of solder wire near the adjoined area so that it melts around it properly. Same process is applied for the other end also.
• Allow to cool down the soldered ends and remove the excess amount with the help of a rag.
• The Gate valve is now fixed in the piping system.

Do you Solder a Gate Valve open or closed

Generally, each manufacturer has a recommendation for open or closed state of the Gate valve at the time of soldering.  Therefore, it is beneficial to go through the manufacturer’s guidelines before starting the work

As per the experts’ opinion Gate valve should remain in a closed state at the time of soldering. Gate valves are most widely used in industrial sectors for starting or stopping a flow. Gate Valves are not suitable for regulating service.

Before installation of a Gate valve, detailed verification of operating fluid, environment, pressure, and temperature are necessary. The installer should ensure the limit of pressure and temperature that may be sustained by the Gate valve.

•  

Image credit: Gate valves https://hardhatengineer.com/gate-valve-types-parts/

How do you Solder a copper gate valve?

The soldering flux paste used for copper soldering is Superior No.135 (rosin/petrolatum). This flux provides protection to the soldering area and is ideal for copper soldering.

The basic steps of soldering copper gate valve are as follows:

• Collect all the necessary tools at one place like a propane torch for heating. Arrange tinning flux or paste flux and lead-free solder.
• Cut the pipe with a tube cutter.
• By inserting and twisting a reaming attachment, the inside burrs at the cut ends of the pipe can be removed.
• Clean dirt and corrosion from the outside pipe surface with an emery cloth.
• Inside portion of the pipe should also be cleaned using a wire brush.
• Brush an even layer of flux over the pipe surface and inside the valve, the same way as you apply butter on a toast.
• Heat the joint with the help of a propane torch evenly and allow itthe solder to meltso that it flows into the joint and seal it. A full joint on all sides should be obtained.

How do you Solder a brass gate valve?

The main difference between copper and brass is that brass requires much more heat for the solder to work efficiently.

As an alloy of copper and zinc, Brass is companionable with copper. Solder adheres to copper as well as brass properly, and fittings are generally molded with slip joints and can be easily soldered to the pipes.

More often than not, you would encounter a brass valve while looking for a valve to solder in a copper pipe. The amount of heat required to melt the flux inside a brass valve is around 5-6times that of a copper valve. Hence, in order to ensure that the flux has properly set in between the piping and the valve, sufficient time must be provided for heating.

What position should a gate valve be is to be soldered?

Gate valves are suitable for all types of applications, both above-ground and underground installations.

Most convenient position for all models of Gate valves (inclined, horizontal, and vertical) with the flow in both directions is installed horizontally with the hand wheel pointing in the upward direction.

The position should be selected in such a way so that it can be easily accessible during operation, inspection, and maintenance. A horizontally placed Gate valve is always easy to operate and also easily accessible for maintenance. However, there are some industrial applications where installing a Gate valve vertically downward is preferred. This is to ensure that the valve remains in an open position, even if the lock-nut holding the gate to the spindle has broken and the gate has fallen off.

How to Solder a ball valve?

Soldering a ball valve is a very familiar and frequently used project in plumbing. The soldering technique of ball valves is not a complex process and can be performed without any professional guidance.

To perform correctly, one should have proper knowledge of the whole process. The step by step process for soldering a ball valve is as follows.

• Assemble all the necessary tools like tinning flux, lead-free solder, a ball valve, pipe cutter, pipe cleaner, heat source, safety gloves, etc
• Cut the pipe with the help of a pipe cutter and clean the two ends thoroughly.
• Apply a layer of flux with the help of a brush on the two pipe ends and inside the ball valve also.
•  Place the ball valve in between the cut ends of the pipe,
• According to the manufacture’s guidelines, keep the ball valve in the open or closed position during soldering.
• Apply heat to the pipe and ball valve area. It is important to note that the body of the valve should not come under direct fame as otherwise, the nylon seal inside the valve may be melted.
• Apply the solder on adjoined areas and continue heating until the solder melts and fills up the gap.  Let the pipe cool down.
• One of the most commonly asked questions is whether to solder ball valves in an open or closed position.Both open and closed option is suitable for soldering ball valves. But it is advisable to solder ball valves in a closed position to avoid the chance of formation of blowing gas bubbles in the joint.
• In the closed position, air generally exits the pipe. On the contrary, there are certain risks involved in soldering a ball valve in an open position. In the open position, water may be trapped in the seals or pipes, which get convert into steam due to the application of heat during soldering. Steam may blow out the seal causing damage to the valve.

Image Credit: Soldering of Ball valves https://www.pressreader.com/usa/the-family-handyman/20180501/282437054662433

Can I Solder a closed ball valve with water on the other side?

Soldering a closed valve with water on the side is beneficial.

It is possible to solder a ball valve with one side in live condition. The application of heat during soldering should not be too high to melt the seals. Otherwise, it may result from a bleeder port. Wrapping a wet rag is always suggested for better results.

To remove the heat produced during soldering, it is normal practice to wrap a wet cloth to remove the heat away. If water is present on the other side, it is beneficial as it will help to remove the heat generated by the soldering process. Care must be taken so that you don’t heat the side with water as it might lead to vaporization of water leading to the blow-up of the ball valve seal.

Can you Solder near Teflon tape?

Teflon tapes or PTFE (Polytetrafluoroethylene) is a common name in plumbing, most widely used for sealing pipe threads. Breakdown may occur in contact with open flames.

The applicable temperature range of a Teflon tape ranges from -268°C to+260°C. Generally, a Teflon tape can withstand temperatures upto 260°C, rate of decomposition is slow up to 400°C. During Soldering near PTFE tape, this temperature range should be maintained.

What is used in Soldering?

Soldering is a joining process most widely used in manufacturing electronic equipment, joining and sealing pipes in the plumbing trade, and also in the jewelry business.

The list of essential items required for any kind of Soldering process are:

• Solder: The main ingredient of the Soldering technique melts to join different types of metals. Traditionally an alloy of tin and lead (Sn 60% & Pb 40%). Nowadays, due to lead toxicity, most of the solders are lead-free, which is an alloy of tin with other metals like copper and silver.
• Soldering Iron: It is a handheld tool that is the main source of heat to melt the solder. Generally, it has a pencil-like shape and very comfortable and easy-to-handle tool. As per the requirement, it may also be available as larger solder guns.
• Soldering Flux:To achieve a good solder joint, a fresh and proper chemical flux is essential. Flux removes oxides from both the metal surface and solder surface so that molten solder can wet the clean metal surfaces to be joined. Resin, Organic, and Inorganic are the different types of flux used as per the requirement.

Soldering valve to copper pipe

Soldering a valve to the copper pipe can be tricky or an easy task at the same time.

The basic steps and precautions that are to be taken for proper soldering of a valve to a copper pipe are as follows:

• The workmanship of an effective Copper pipe soldering depends largely on sticking to the basics, which are: – right preparation, right tools, and rights methods
• Get all your tools in places like the flux paste, the propane torch, the solder, a piece of sandpaper, the pipe cutter, and of course, the valve and the pipe.
• If the soldering is in a live line, ensure the line is drained properly and the source of inlet water is isolated. Then cut the pipes with the pipe cutter.
• Once the pipes are cut, it is necessary that the surfaces at both ends of the cut pipe are properly rubbed with the abrasive sandpaper so that a shine appears over the surfaces to be soldered.
• The next step is to dry-fit the valve, and it is to be ensured that the valve fits into both sides snugly.
• Apply the flux properly on both the surface as you apply butter to a toast!!! And install the valve.
• Before you start heating, ensure the valve is at least partially open. This is done so that if there is any residual water left in the pipe, it doesn’t pressurize the system and crack the soldered joints.
• Lit up the propane torch to heat the surface to melt the flux within.
• Once the flux has melted, the primary sealing is done. The next step is to bring in the solder.
• Continue heating with the propane torch to melt the solder so that it is assimilated into the gap between the pipe and the fitting, thus providing a leak-proof fitting.
• Once it is ensured that the solder has got into all the cracks and crevices of the fitting, let it cool down before being put into service. This is to ensure that the newly soldered joint does not crack due to thermal shock.

How to Solder brass valve to copper?

It is not a big deal to solder brass valve to copper pipe if we are aware enough about certain facts. The temperature of the pipe should be hot enough at the time of applying the Solder.

It is advisable to perform soldering of brass valves correctly in the first attempt because redo may create the problem. When the metal surface reaches the accurate temperature, the plumbing solder flows into the joint between the pipe surface and valve by capillary action and, after cooling, results in a watertight seal.

To avoid a leaking joint, make sure that the moisture inside the pipe can escape completely when it turns into steam.

The same steps are followed as discussed above for soldering valve to copper pipe.