Ever wonder how industrial valves are made? The pipe system is not complete without valves. Since safety and service lifespan are the top concerns in a pipeline process, it is crucial for valve manufacturers to deliver high-quality valves.
What is the secret behind high functioning valves? What makes them better in performance? Is it the materials? Do the calibration machines matter that much? The truth is, all of these matters. Before even understanding the minute details of the industrial valve, one needs to know more about how valves are made.
This article will discuss the manufacturing of industrial valves from beginning to end. This would provide readers information about valve manufacturing and processing.
1. Order and Design
First, a customer should put an order, whether that is a customized valve or something found in the list of already-available valve designs. In the case of a customized one, the company shows a design to the customer. Once approved by the latter, the sales representative puts an order. The customer also provides a pre-defined deposit to the company.
Once the placing of the orders and design commences, the manufacturing department will look for the raw materials for the stem, spool, body, and bonnet. If there are insufficient materials, the manufacturing department will procure these materials from suppliers.
3. Completing the Checklist
Once the materials are all present, the manufacturing team goes over the list again to ensure that everything is complete. It is also at this time that approval for the final draft of the design happens. Additionally, the quality assurance team checks the materials thoroughly. This is to ensure that the raw materials are of the best quality.
4. Production Process
This encompasses the majority of the activities pertaining to the manufacturing process of industrial valves. Each major components are made individually. Often, there is a checklist that entails all the names of the spare parts and what material to use for each.
It is at this point that the team leader provides a timeline for the actual manufacturing, from the start of the operation to the completion date. Also, the leader often draws up a detailed operational plan.
Discussed below are the two common methods of how valves are manufactured.
#1: Cast Method
The cast method can be summed up by looking at the illustration below. Note that this is not the complete process.
An initial pre-shaped material cleaned. A turning process is done after cleaning. Turning is the method of removing excess material by cutting using a lathe or a turning machine. It involves attaching the pre-shaped body to a mount and to the turning machine. This machine rotates at a high speed. While it rotates, a single-point cutter cuts the body into the desired and specific shaped. Other than that, turning can also create grooves, holes, among others.
The next step is to add a plating metal, usually, copper to different sections of the body. Copper plating ensures complete and proper sealing of the body.
The next step is the polishing of the body. Then, technicians create the threads that allow attachment of certain valve parts to other components or the pipes. Valves need holes so holing also happens after this. Take note that each valve has different hole sizes, depending on the requirement. This is where regulations and standards come into play.
Technicians then paint the valves with Teflon or other types of elastomer. After painting, baking ensues. Teflon bonds with the body through baking.
The seat undergoes the same process as the body. Since the seat is inside the body and as part of its valve function- for better sealing- it needs perfect fit to its attachment. Whereas the body only has Teflon, the seat as an additional rubber wrapping to ensure tight fitness.
As in the case of the stem, it does not need to have much manufacturing. Rather, cutting these in the right dimensions is important.
#2: Forged Method
The forged method can be summarized in this process below. Similarly, the process below only highlights what the forged method is.
● Cutting and Forging
After the selection of the material, the next process is to cut them into the required lengths and widths. The next step is to forge each part by partially heating them to a certain degree.
The next step is trimming. This is where excess material or the burr is removed. Next, the body is flashed to mold it in the right valve shape.
Sandblasting is the next step. This makes the valve smooth and clean. The size of the sand used depends on customer requirement or standards. The valves are initially sorted out to remove the defective ones.
Machining further enhances the sizes and shapes of threads, holes and the likes, again, depending on the design and requirements of the customer.
● Surface Treatment
The valve undergoes some treatment of the surface using certain acids and the likes.
Assembly is the phase where technicians attach all the valve components to one another. Often times, the assembly is done by hand. It is at this point that technicians assign the valves production numbers as well as designation according to the regulations it follows such as DIN or API and the likes.
6. Pressure Test
In the pressure test phase, the valves have to undergo actual pressure testing for leakage. In some cases, air with 6-8 bar pressure fills the closed valve for a certain number of hours. It could range from 2 hours to a day, depending on the valve size.
If there is a leak after the timeframe, valve repair happens. Otherwise, the valve will move on to the next phase.
In other cases, leakage is detected through water pressure. If the valve does not leak as the volume of water increases, it passes the test. This means that the valve can withstand the increasing pressure. If there is some leakage, the valve returns to the warehouse. The technicians will check for leakages before performing another set of pressure tests to this batch of valves.
7. Inspection and Quality Control
At this point, QA personnel would inspect the valves thoroughly for leaks and other production errors.
The industrial valve manufacturing process is a complex endeavor. It is not just a simple creation of the valve. Many factors contribute to its efficiency: raw material procurement, machining, heat treatment, welding, assembly. Valves should undergo rigorous tests to ensure proper functioning before manufacturers hand them over to the customer.
One might ask, what makes a high-quality valve? One of the determining factors for knowing high-quality valves is the test of time. Long service valves mean they are of good quality.
On the other hand, when the valve shows internal leakage, chances are, the manufacturing methods employed are not within the required standards. Typically, better valves can last up to 5 years while the low-quality ones can only last up to 3 years.