Author: User@kavaatavalves.com

The design of ball valves involves the use of many international standards for producing high-quality products. These standards cover the materials, dimensions, tolerances, and marking for ball valves, ensuring that they can handle the pressures and temperatures they are designed for. Different countries use different standards which makes it important for the manufacturer located anywhere in the world to design and produce the proper product. Essentially, the functional design of the valve is fairly common though the end connections are country-specific or region-specific. For example, the projects executed by American companies normally have NPT threaded valves whereas the projects by European companies have BSP threaded valves. Similarly, the flanged connections on valves follow ASME or DIN standards depending upon American or European contractors. The Japanese have their own flange standards prefixed with JIS.

The British standard BS5351 was used extensively for ball valve design until it was replaced by ISO 17292 standard. API 6D is the American equivalent standard for ball valve design. Both the standards are similar in content except for some minor differences. In India, we generally use ISO 17292 standard in conjunction with ASME B16.34 standard. ISO 17292 provides all the necessary information- namely bore diameters for reduced and full bore ball valves as per pressure classes, the basic structure of ball valves for both floating and trunnion mounted, butt weld end and socket weld end dimensions, ball and stem design, seat selection depending upon temperature, testing procedure, markings on valves, etc. ASME B16.34 standard provides the wall thickness details depending upon the material of construction, pressure class, and temperature of operation of the valve.

Most ball valves used in India come with ASA flanges which have dimensions as per ASME B16.5 standard. This standard provides the dimensions of flanges depending upon the pressure class and size of the valve. Under the ASA regime, the pressure classes are specified by numbers such as 150#, 300#, 600#, 1500#, and 2500#. Each pressure class is suitable for working in a specific pressure and temperature range. DIN standards follow a more straightforward approach. The pressure classes are denoted as PN10, PN16, PN25, PN40, PN100, etc. which represent maximum working pressures in the bar.

There are projects executed by European contractors which have ball valves with DIN flanges. Replacement of DIN flanged ball valves with more commonly available ASA flanged ball valves require one-time replacement of pipeline flanges with suitable ASA flanges.

The distance to be maintained between two pipeline flanges is decided by the face-to-face length of the ball valve. This length is provided by ASME B16.10 standard. Valves manufactured in accordance with ASME B16.10 standards can be fitted and replaced with similar valves onto the pipelines whenever required.

Testing procedure for ball valves prior to dispatch is specified in BS6755 Part 1 and Part 2. BS6755 Part 1 gives the testing procedure for normal ball valves whereas Part 2 gives the Fire Safe Test procedure. Similarly, API 598 provides the required information for valve testing. API 607 provides the Fire safe test procedure.

Other important standards are ISO 5211 which provides the dimensional details for actuator mounting pads provided on valves. NACE MR0175 provides the requirements for crack-resistant material to be used in oil and gas environments containing H2S. ASME B16.11 standard gives the dimensional details for threaded ends, socket weld ends for fittings.

It is very important for a valve designer to understand the importance of designing valves as per the standards mentioned above. All valves which comply with the requirements specified by the customer and the corresponding constraints suggested by the standards become a reason for customer delight. In our pursuit to exceed customers’ expectations each time, every time, the Kavaata team takes special care to follow all the requirements set out by the International standards so that the product meets or exceeds our customers’ requirements.

Ball valves with soft polymer seats are used where tight shut off of flow is required. This excellent shut off capability of polymer seats comes with a downside- high temperature service constraint. All soft seated ball valves can work at maximum temperatures dictated by the seat and seal properties. In case of a fire incident at the site/ factory where these valves are installed, it will result in melting or vaporization of seats leading to massive leakages of pipelines. To avoid such an event, fire safe ball valves were introduced. These ball valves have additional secondary metal seats, which comes into play, when the soft seats melt due to heat, caused by a fire. The major part of the leakage is arrested if the fire safe ball valve is in closed position at the time of the fire event. Such ball valves are certified as fire safe after clearing a test specified under API 607 standard, which is basically a standard for isolation valves.

Let us now shift our focus to 3 Way ball valves. 3 way ball valves are used for flow diversion. Hence, the 3 Way valves function like elbows. It is quite clear that elbows do not stop the flow of fluid but merely divert the flow through 90 degrees. When we apply the conditions of fire safe testing to a 3 Way ball valve, we find that in the case of a fire incident, the 3 Way valves shall continue to allow fluid to flow through them. The polymer seats will melt due to the temperature but providing a secondary metal seat will not make a 3 Way ball valve fire safe.

Some manufacturers of 3 way ball valves do provide a fire safe certificate with their valves. The only way a fire test can be conducted on a 3 Way ball valve is by shutting one outlet and using the other two ports for pressurizing and for leak testing. However, this arrangement does not mimic actual conditions of usage where the shutting of one outlet is not possible. As written above, one port shall continue to allow passage of fluid under normal working condition. The arrangement for fire test by shutting one outlet, does test the fire safety of the secondary metal seat on the closed side, yet does not satisfy the conditions of API 607 standard.

There is one more unique issue in the case of 3 Way L Port ball valves which does not allow for successful fire safe test. In case of a two way valve, the ball inside the valve has the ability to float towards the downstream seat when pressure is applied. This characteristic is exploited to the hilt during fire safe testing. Once the primary polymer seats are destroyed, the ball keeps on floating under pressure towards the secondary metal seat and seals the possible leakage. However, in the case of an L port 3 Way ball, the floating of the ball occurs only in one direction. If the valve is rotated by 90 degrees, there is no floating of the ball. During fire safe test of a 3 Way ball valve with one outlet shut, the ball is arranged in such a way that it can float towards the metal seat. The valve in this configuration may pass the “fire safe test”. However, if the ball is rotated by 90 degrees such that there is no floating possible, the valve will definitely fail the fire safe test. What this means is that the fire safe test is staged to suit the convenience of the manufacturer because it can pass only in one possible configuration.

Any ball valve can pass the fire safe test only when enough pressure is built inside the valve to force the ball to float and minimize leakage. The fire safe test must mimic actual working conditions as the valve should prevent a catastrophe during a fire incident. If a fire incident does occur, a 3 Way ball valve shall continue to allow flow of fluids towards one port. This does not satisfy the requirement of the standard. It may allow or prevent the flow to the closed port depending upon whether the ball is in floating or non- floating configuration, at the time of the incident. Thus, even if someone were to argue that the valve minimizes flow through the closed port during a fire incident, it is clear from the above information, that the valve can work fire safely, only 50 percent of the time. No standard or engineering practice can certify a product as conforming when it fails half the time. Hence, 3 way ball valves cannot be fire safe.

At Kavaata Valves, we provide a variety of materials for ball valves. These valves are important for different industries, as they control the flow of liquids and gases. Read more about the different materials for ball valves here. Ball valves are often used in various processes. The use of ball valves in various industries has meant that several materials have been used in their manufacturing. This blog talks about the different materials of ball valves and what they are used for.

Kavaata ball valves are made from the best materials, and they are manufactured to the highest standards. They are suitable for use in various demanding applications, such as food, biotech, pharmaceutical, chemical, oil and gas, mining, power generation and more.

Choosing the right materials for ball valves is always a challenging issue. You should be well aware of the operating parameters before choosing the material. The most important parameters are – Operating Pressure, Operating Temperature, Type of Fluid or gas flowing and Application.

Ball valves offer a wide range of materials, from plastic to metal to ceramic. Metal ball valves are used the most, and this is the type of valve that we will focus on.

Types of Materials used for Ball Valves

1. Carbon Steel – WCB is a very common material for ball valves, and is often used in both cold and hot water applications. Carbon steel valves are not ideal for use in applications that are exposed to strong acids or bases, as the valves will corrode. Another disadvantage of carbon steel is that it is not ideal for extreme temperatures, and should not be used in temperatures below zero degrees Fahrenheit. WCB (as carbon steel is commonly called) is a type of cast alloy that exhibits good strength, toughness and ductility. It is typically used in structural applications with elevated temperatures and pressures. WCB is an iron-based alloy that is commonly used in a variety of applications including valves, fittings, flanges, pipes and ducting.

2. Stainless Steel – CF8 is not only stronger, but it’s also better in every aspect. That’s why CF8 is used in the most demanding and critical applications. CF8 has superior tensile yield strength than WCB. It also has higher impact strength, lower modulus of elasticity and higher thermal conductivity. CF8 is non-magnetic and has higher heat resistance, so it is ideal for applications with high operating temperatures. CF8 also offers a wider range of chemical resistance. CF8 is compatible with hot water, steam, seawater, molten salt, phosphates and many other chemicals. CF8 is the best choice for your ball valves, and our team can help you find the right solution for your valve application.CF8 is a grade of austenitic stainless steel used in applications where toughness, strength, and corrosion resistance are required in a non-oxidizing environment. It is used in the food, chemical, petroleum, and pharmaceutical industries. The alloy composition of 18% chromium and 8% nickel gives the material a high corrosion resistance. The high chromium content of this grade makes it suitable for many low-temperature applications such as cryogenic storage. CF8 is an excellent material for high-temperature applications where its high strength, toughness and corrosion resistance are required.

3. Stainless Steel – CF8M is a grade of austenitic stainless steel used in applications where toughness and high strength are required in a non-oxidizing environment. It is used in the food, chemical, petroleum, and pharmaceutical industries. The alloy composition of 18% chromium, 10% nickel, and 2% molybdenum gives the material a higher corrosion resistance. The high chromium content of this grade makes it suitable for many low-temperature applications such as cryogenic storage. CF8M is an excellent material for high-temperature applications where its high strength and corrosion resistance are required.

4. Super duplex stainless steel is a type of alloy which has both the characteristics of ferrite and austenitic stainless steel. The various grades contain about 25% of chromium and at least 5% of nickel. Because of its high nickel content, the alloy’s corrosion resistance is very similar to that of the 18-8 stainless steel with the addition of superior mechanical strength and creep resistance at higher temperatures. Duplex stainless steel is highly resistant to chloride pitting and crevice corrosion, but is not as resistant to sulfide stress corrosion cracking, although it is still considered a good choice for sulfide service. It is used in many applications where improved corrosion resistance, high strength, and/or constant magnetic susceptibility is required. It is the usual material of construction for nuclear power plant heat exchangers, process piping, and marine applications. Duplex stainless steel is an excellent material for chemical processing equipment, due to its superior resistance to acidic or caustic environments. It is also used for valves and pumps in the process industry.

5. Hastelloy is a nickel-based superalloy. Hastelloy alloys are resistant to corrosion in many chemicals and at high temperatures. They are typically used in applications such as nuclear reactors, chemical processing, steam boilers, and oil refineries. Hastelloy is widely used in the petrochemical industry and the chemical process industry. Hastelloy alloys are also used in power generation, marine applications, and metal forming operations. Alloys in the Hastelloy family have excellent resistance to many corrosive environments, as well as excellent mechanical properties at elevated temperatures.

We hope you enjoyed our article about various materials used for ball valves. Because ball valves are used in such a variety of industries, we are sure that you can find a valve that will work in your environment. With this knowledge, we know that you can find a ball valve that will work for you and your business. So what are you waiting for?

Visit – www.kavaatavalves.com today to learn more!

3 Way L Port or T Port ball valves are used in flow diversion applications. These valves are used extensively in duplex filters and duplex heat exchangers. Here, the valves perform the function of diverting the fluid from one filter or heat exchanger shell to another. Throughout the movement of the ball, when operated, the flow is not interrupted or brought to a halt. This helps to control pressure surge and makes the 3 Way ball valves ideally suited for the application. Two 3 Way ball valves are connected by a common lever in such a way that both valves operate together when a common handle or gear is operated. Sometimes, it becomes very difficult to maintain the collinearity of the two stem axes due to the distance between the valves. In such cases, Kavaata valves provide common levers with flexible couplings to avoid side loading of stems and consequent leakage.

Sometimes, in compact duplex filters, there is a specific need to bring the valve centers closer. This is not possible to achieve with two 3 way ball valves as described above, as it is imperative to have a minimum distance between two valves when they are connected, to accommodate the two stems and the common lever. Here,
Kavaata 6 way ball valves are the only option available. The concept of 6 Way ball valves involves using two tandem 3 Way ball valves. Instead of connecting the two stems of the 3 way ball valves, here the stem and ball of the valve on top drive the stem and ball of the valve below.

In-line inlet and outlet 6 Way valves

A 6 way ball valve is shown in the picture. 6 Way ball valves manufacturing involves very high degree of machining and assembling accuracy. Any misalignment can lead to leakage and increased operating torque. Kavaata valves have made a name for themselves by providing bespoke solutions in 6 Way ball valves to customers. Another variation in the design of 6 Way valves is the In-line inlet and outlet 6 Way valves. The picture alongside shows one such arrangement. Here, the inlet and outlet of the filter are in-line or collinear.

It can be seen clearly that the 6 Way ball valves are very compact and can be used in applications where space constraints exist. One 6 Way ball valve can effectively replace 4 two way butterfly or 4 two way ball valves. In addition, the simultaneous operation eliminates human errors which can creep in while operating 4 valves independently. The variety of 6 Way ball valves, the size options available with Kavaata Valves and the customization is endless and limited only by imagination.

 

There exists a common misconception in the minds of end-users of valves, with regard to the flange thickness of 150# and 300# valves. This is due to the fact that the ASME B16.5 standard treats these two pressure class valve flanges differently when compared to the other higher pressure class valve flanges. The flange thicknesses in the case of 150# and 300# valve flanges are required to be in accordance with the flanged fittings table and are lesser than the flange thickness for the corresponding class pipeline flanges. Sometimes, end users are confused as to whether they should accept valves with thinner flanges than the corresponding pipeline flange thicknesses.

The reason for the confusion stems from the fact that the explanation for this anomaly is given in section 6.2.2 of ASME B16.34 standard and not in ASME B16.5 standard. Section 6.2.2 of ASME B16.34 states that “Flanged ends shall be prepared with flange facing, nut bearing surface, outside diameter, thickness, and drilling in accordance with ASME B16.5 requirements for
(a) flanged fittings for Class 150 and 300 valves
(b) flanges for Class 600 and higher valves”

In light of the above, it is important to understand that Class 150# and 300# valve flanges shall follow the flanged fittings table and shall have lesser flange thicknesses compared to the corresponding pipeline flanges.

Procurement of valves for a project presents itself as a challenge to the Project manager. This is because of the variety of valves required in a project- be it ball valves (manual or actuated, floating or trunnion mounted, two way or multiport), gate valves (rising stem, non-rising stem or knife gate valve), check valves (swing check valve, non-slam check valve or lift check valve), globe valves (regular or Y type globe valve), butterfly valves (lug type or flanged type), plug valves (two way or multiport, manual or actuated), hydraulic valve for high pressure, pinch valves for slurry and the list goes on.  Further, there is a classification based on the material of construction (WCB, CF8, CF8M etc.) and end connections (screwed end- BSP, NPT, BSPT, NPTF etc, socket weld end, butt weld end, and flanged end). Flanged end valves are further classified into pressure classes like 150#, 300#, 600#, PN10, PN16 etc. and country wise standards like ASA, DIN, JIS, BS, EN etc. Of course, size of valves range from 1/4″ to 60″ and above- Phew!

The sheer variety of valves makes it impossible for one company to manufacture all types. Unlike hardware items like bolts, nuts, pipes etc. which are normally available ex-stock, it is impossible for any one company to maintain an inventory of all types of valves. Valve requirement, quantity, size, and type, typically undergoes a number of changes as the project implementation progresses. Hence, the final list of valves required is available only as the pipeline work nears the end. This leaves the project manager very less time for the ordering and procurement of valves. The project manager has to rely on his project a consultant’s recommendation for supplier selection or scout for new manufacturers. The tender process, technical and commercial negotiation and final order generation take up a good chunk of the available time.

Valve manufacturers are always at the receiving end as the time allotted for supply is much less than what is normally required. Valve manufacturers knowingly accept L-D Clause terms, like a discount, while accepting an order. Valve industry is not looked upon as a manufacturing entity with its own set of problems and lead time requirements. This is mainly because the ratio of the total cost of valves to the project cost is very small. The fragmented and specialized nature of manufacturing ensures that valve manufacturers remain small compared to the customer size and hence are not accorded any importance.  Valve manufacturing is a batch process and not a continuous high volume process. What is forgotten is that a delay in supply of valves can bring the entire project implementation to a halt and lead to huge losses. Foundries who supply castings to valve manufacturers work under huge time constraints. Sometimes there are casting defects which can undermine the quality of valves. These show up at the very end of the manufacturing cycle at the valve testing stage and brings more misery to valve manufacturers. Rework, rejection or replacements are required which further delays valve supplies. To add to the misery, sometimes, third-party inspection agencies appointed by customers, do not have inspectors available to conduct a timely inspection. This leads to further delays.

In view of the above, it is imperative that project consultants, project managers, and customers allot sufficient time, typically 6- 8 weeks for good quality valve manufacturing.  Some understanding of the typical problems faced by valve manufacturers will go a long way in early ordering for valves and reduce project delays. It is hoped that this post shall help all concerned to  E-Valve.