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Advanced Control Valves COURSE — Free Demo Lesson [Join Now]
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Sep 5, 2025
Free demo from our Advanced Control Valves course—learn Cv sizing, trim choices, noise & cavitation fixes with real plant tips. Course Join Link: https://learn.advanceinstrumentation.com/services/gfdl #controlvalve #course #valve Tags: Advanced Control Valves, Advanced Control Valves course, Free demo lesson, Control valve training, Control valve sizing, Cv, Kv, Trim selection, Equal-percentage vs linear, Valve characteristics, Rangeability, Installed gain, Cavitation prevention, Noise prediction, IEC 60534, ISA-75, Severe-service valves, Anti-cavitation trim, Globe valve, Ball valve, Butterfly valve, Choke valve, Positioner tuning, Smart positioner, Actuator sizing, Bench set, Stroking test, PID interaction, Split-range control, Flashing and erosion, Valve capacity, Process control, Instrumentation course, Join now
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0:30
We'll try to divide the webinar into four sections. So first 15 minutes we will focus on the valve body selection.
0:37
Then the next 15 minutes we'll focus on the trim selection especially which type
0:42
of trim to be selected and we'll try to have some kind of you know thumb rules or kind of like an algorithm so that you
0:48
know when you make your data sheet you have a basic idea of okay fine for this application this should usually be the
0:54
trim type selection. Then next we will look at material selection. Again these
1:00
these four points I have come across by your questions only over the years at least for the past 8 years whenever I
1:06
have seen these were usually the four questions and the final one was control valve standards also at least and you
1:13
should have an overview not in depth but at least you should know the basic international standards that are
1:19
applicable when it comes to control valves. First is the selection process. So let us first start with understanding
1:24
the valve body selection as a first case. So I would start here by explaining is basically you know if you
1:29
want to protect yourself and uh should you use a mosquito repellent or should you use a machine gun for example. Now
1:37
this question sounds ridiculous but if you actually look the answer is not clear. It depends on what is in front of
1:44
you. If it's just a cockroach you know the mosquito repellent or the cockroach repellent would be very good for you but
1:50
a machine gun even though is better but it's oversp specified. So the first
1:55
thing in the valve selection which some of you said in the comments is basically
2:00
to understand the exact application. Once you know the application, we will
2:06
go into uh details of what in the application you should know. But the point is first you should know the
2:12
application where do you want to apply the valve and that is where we go forward. For example, if you have a
2:18
dinosaur, for example, your mosquito repellent would definitely not be, you
2:23
know, sufficient for that case. In that case, you definitely need a machine gun even though it is costly. So, you should
2:30
know the cost difference between various kind of valves. But that is not the only
2:36
criteria to select. First is you need to know what you're dealing with and then you can select based on your
2:42
application. For example, how can you be cost effective plus technically compatible at the same time? Let us look
2:48
as to how to understand a particular application. Now when we go here, the first thing we need to understand is is
2:55
the application requiring precise flow control or not. Let me give you an example. For example, let's say you have
3:02
a utility service. Now utility service, you don't require it to be completely
3:08
precise. However, if you are exporting or if you are having petroleum products or for example it's a paint line where
3:14
you know you need to mix in a certain proportion there your precise flow becomes very important in that case you
3:22
have to first know is how is your application does it require very precise flow or not. Second thing is
3:28
differential pressure. Okay, one of my friends in Shell, he told me one thing to remember. If you want to do control
3:34
valves, differential pressure or the pressure drop across the valve is going
3:40
to be your number one characteristic that will help you to understand which
3:46
valve, which trim in control valve sizing, in selecting the correct CV for
3:52
everything your DP becomes extremely important. So this is what we have to
3:58
pay very attention how much is the differential pressure. It is less for example five bar two bar or if it is 50
4:05
bar 100 bar of pressure. So as the pressure changes your selection has to
4:11
definitely reflect that. Third thing is what I call CFC and issues. We will deal
4:16
with that as we come there. And finally is your budget a least in the list but
4:22
according to clients and your uh end users definitely that is one of the most
4:27
important thing to them but as an engineer I put that at the last first is because to understand that if it follows
4:34
the first three criteria only then can you look for budget if your valve cannot cater to application it doesn't make
4:41
sense even if your valve is the most cheapest then you have some smaller parameters also like the leakage
4:47
requirement ment line size and other I think around 20 parameters but these four have usually been the strong
4:53
parameters while deciding any application. Now first let us look into the cost effective pattern. Okay. Now
5:00
when you get to cost effective pattern what I would suggest is there are a lot of valves available with
5:06
us but with respect to their design not all of them are good for control. So let
5:12
us ignore as of right now is gate valves and the common ball valves. We'll keep
5:17
segmented ball valves, plug valves with us. Plus we'll keep is globe valves and butterfly valves because these are
5:23
usually the four types which are usually used for control applications. For special applications you have diaphragm
5:29
seals, diaphragm type valves etc. But those are very you know very high viscous applications and very specific
5:36
industry related stuff. So let us first discuss is overall as a graph. Now when it comes to your application you have
5:43
butterfly, segmented ball and globe. Now here which is the most cost effective
5:48
option. Ideally speaking in a very broader picture butterfly valves are
5:53
usually the most cheapest. Then comes your segmented ball and plug valves and
5:59
then comes your globe valves. If you see logically also a butterfly valve is a very thin valve with completely you know
6:06
uh the material itself used to make it is less. Then comes your segmented ball
6:11
or plug valves. And then if you see the globe valve design with respect to its complex flow path it is very difficult
6:18
to manufacture it very cheaply. So comparatively if you see butterfly we
6:23
can keep as of now a segmented ball and plug and then the globe pack. I would say maybe you can imagine the butterfly
6:29
valve just for our uh understanding kind of like the cockroach. So wherever the application is simple as an engineer
6:36
your first chance is to see whether can you have butterfly valve implemented there. If that doesn't work out then you
6:42
look for whether segmented plug can work or globe can work. Now let's look into the second important point size. Okay.
6:50
Now the budget will greatly depend on your line size. So as somebody said in the comments very clearly as the line
6:56
sizes increases the impact of the size on globe valve will become two times
7:02
four times it will increase dramatically as your line sizes increases and also the maintenance will become tougher. So
7:09
in that case if your line size is very large first look can you make butterfly
7:14
valve fit in your application. If not then look for segmented ball or plug valve design and if nothing works out
7:21
then maybe you can look for a globe valve design or you should consult a specialist if the line size is too big
7:28
because globe valve maintaining at such high line sizes and with such a huge
7:34
pressure drop is something tricky. The second application or the point which we discussed was precise flow. Now when it
7:41
comes to precise flow, we have globe segmented ball plug butterfly. Can you tell me which one has the most precise
7:48
flow control capability available with them? Globe has definitely the winner. You go to any you know control valve
7:55
whether you go to manufacturer, you read any reference book, any standard, global val definitely wins here. They have very
8:02
precise control. So if you're having some petroleum products etc. Definitely you should first go for globe valve
8:08
regardless of the cost if you want precise flow control especially critical application here is CFCN. What I call
8:14
CFCN is cavitation, flashing, choke flow and noise. For these four issues which
8:20
is usually what a control valve mostly faces here the valve selection again becomes important. If you have any of
8:27
these four criterias then which valve is better for you in terms of the solutions for such cases. If you see the CFCN is
8:36
basically also having a relation to differential pressure. What I mean by that is if you would look into your
8:42
control valve sizing or if you have already done you would notice that the applications which have higher DP which
8:49
have challenging DP values would mostly be experiencing these CFCN issues which
8:54
is cavitation flashing choke flow noise etc. So I would see kind of they're
8:59
interrelated to each other. So for applications which have high differential pressure or you have
9:04
already experienced CFC and happening through your calculation for those applications which valves should you
9:10
choose? The answer has to be out of the three it is definitely going to be globe
9:16
valves. Why is that the case is because globe valves first of all they have lot
9:21
of options. For example if you want low noise trim for you want to have you know different kind of characteristics it
9:27
becomes easier when it comes to and handling. If you see a butterfly valve in terms of its construction, it's
9:34
basically a vein which is rotating. So now imagine at especially I would say 60 or 70 80° that is when at that time to
9:42
maintain its state at a very high DP. Let's imagine 100 bar of DP. It's too difficult. It will start to vibrate
9:48
here. So it's very difficult. You have certain valves which have come in the market which are called as triple offset
9:54
butterfly valves. But still it is very tricky to maintain that kind of position
9:59
in such high differential pressures. So for that case I would definitely suggest is that you know you should definitely
10:07
go for globe valves as long as it is possible and then you can have in the middle which is your segmented ball or
10:13
plug valves to be used in case if you can cater to those applications. Now getting to industries. Uh can you tell
10:20
me generally for oil and gas which is the most common type of valve used for pulp and paper and for waste water.
10:27
Based on what we learned if you also apply to industries you will generally see that for oil and gas which majority
10:34
of you have answered and seen in your books is that the traditional sector preference is globe. Now when I say
10:41
globe for oil and gas does not mean that it should be globe for any XY Z project XY Z line. It should definitely depend
10:48
in oil and gas also you have utility section where you will have water transporting. So there if you see a
10:53
globe valve you can definitely try to replace that with a butterfly valve and save cost and maybe have a value
11:00
addition as an engineer in the project. So but overall speaking because oil and
11:05
gas projects are generally more challenging in terms of their differential pressures that you will face for example a ethane cracker. So
11:12
all those projects generally you would see that all engineers usually recommend a globe valve. When it comes to pulp and
11:18
paper it is not extremely challenging but not that easy as just water
11:24
treatment plants. So generally they have a you know uh generally they have a preference for segmented ball or plug
11:30
valve design. And finally when it gets to waste water most of you answered
11:35
because those are not challenging applications you might first try to go for a butterfly w. So we'll make a quick
11:41
summary. So first as an engineer when you're looking you will see do you have these three issues there CFC and high
11:47
differential pressure or precise flow control. If that is the case the answer is yes then you should look for globe
11:53
val which is your most costliest option but you have no choice as an engineer.
11:58
If no then you can look for some budget friendly options. For example you will first try for butterfly valve. If
12:05
butterfly doesn't work then maybe you can look for you know some more tough applications. For example, segmented
12:10
ball plug valve which can be in the middle. So basically you have is the best is the globe in terms of the
12:16
overall applications but the most costliest one. In the center you have is ball or segmented plug valve. And
12:22
finally you have is the butterfly valve which is the most cost effective option. Trim type selection. Now this is
12:30
definitely very confusing when it gets to especially globe valves. So when you
12:35
get to trim for globe valve, you have plugg guided trim. You have balanced type, unbalanced type, cage guided, trim
12:43
guided, single port, double port. Then you have characteristics like linear, quick opening, equal percentage. So now
12:50
with all of these different types, it becomes very confusing how to mix and match them together based on a
12:56
particular application. For trim type selection first I would like to you know
13:01
uh make it at least divided into subcategories and then we will explore them. So the first category which I call
13:07
is unbalanced and a balanced trim design. Then the second opposite side on the spectrum is basically where you have
13:14
linear characteristics quick opening and equal percentage. Then you have something called a skage guided design
13:20
and plugg guided trim. And then finally you have dual port and single port globe
13:26
valves available. First thing is I want to explain this concept of you know how these so many these trims come into
13:33
picture with something related to civil engineering. Now in civil engineering you have something called as canty
13:38
lever. Now canty lever is basically a very simple design. If you see canty lever means a support which is given by
13:45
civil department which is fixed at one end and the other end is unsupported. So
13:52
basically if you want you remember I don't know if you have instrumentation trays which have to be laid civil gives
13:59
you this kind of support. So one side it is usually uh fixed and the other side is usually because the trays are not
14:04
very heavy. So they can easily rely on the uh beam that is given. Now that being the case how does this basically
14:12
help in our trim design? Let us look into that point. This design is kind of similar if you see to a valve connected
14:19
to a plug. If you see here the top side is basically the fixed end that we have
14:26
and the bottom is something which is free which is the unsupported end that we have. If you see for any valve
14:33
application for example here this is how your flow is flowing through the valve. Now when you look here at this design
14:40
you can see that because it is supported at one end the other end if there is huge amount of you know I would say
14:47
turbulence or for example very high DP it is very difficult to keep the other
14:52
end stable. It will start to you know kind of oscillate and this is especially
14:58
not good for a valve which needs to have precise flow control and that is how came your dualported design. Now what
15:04
happens here is in the dualported design if you see here as the way it is moving
15:09
it is supported at the fixed end which is from the actuator side and at the bottom also it is supported. So how this
15:16
was helping was if you have very high DP uh this is just I'm giving you a example
15:23
maybe 30 bar 50 bar it depends on your application we will look in the end as to when do you select dualported design
15:30
but just giving an example if the DP is high then your plug is definitely going
15:36
to oscillate a bit so it is better from single port to go to a dualported design
15:41
you would see in majority of the chat very few people a dualported design. If
15:47
this design can cater for high DP and most of you have your experiences in
15:53
challenging applications, why didn't you select a dualported design compared to a single port design? So basically with
16:01
dualported design as some of you said there is going to be an issue. So but
16:06
overall remember one thing when it comes to dual port and single port. Single port valve plugg guided is good for low
16:14
differential pressure applications. Dual port is good for high differential pressure applications. Okay. Then now
16:21
let's look into answering the question why it is not used in most of the applications. The first important thing
16:28
is leakage paths are increased. You have one point of contact with the fluid there. If the shut off is not good, you
16:34
will have some fluid leaking. If you have two ports, definitely it's going to have four parts of leakage available.
16:40
Second is higher cost because the body size is going to definitely increase.
16:45
Then you have the third thing is they are heavier because of the two ported design. They make it far heavier valves
16:52
compared to your regular application. Then this bigger design also has to be accommodated. Again that becomes
16:59
difficult for the size to be available in the plant, the clearances available to remove the valve out etc. So all of
17:06
these factors were actually having an issue and up till 1960s
17:12
engineers had no solution. So it was very clear for them at that point of time if it's less DP low DP applications
17:21
I go for a single port valve. If it's heavier or high DP applications, I will
17:27
go for a dualported design. That was it. But then what happened here is what I
17:33
would like to share is the idea of cageguided came into picture. Now what happens with cage guided is we will get
17:40
to the uh characteristics of trim. But before that what I wanted to explain was
17:45
that cage guided why did the need come for cage guided? If you see here a lot of people also said in high DP I use
17:52
cage guided valves. You are correct. What happens here is in cage guided design is the top end is anyways fixed
17:59
basically with some kind of support. The bottom here is also fixed because the cage will never move. It is the plug
18:06
that moves inside the cage. So now you have better stability at high differential pressure applications. And
18:13
this reduces the idea of leakage path. This red reduces the idea of you know having uh bigger design or two ports
18:21
available also the uh space requirements have reduced. So this seems to make a
18:26
lot of sense. However, there is a big however. If your service has big solid
18:34
particles which could get plugged into your cage then maybe you need to still
18:40
think about dualported design. They are not traditionally used. Most applications you should avoid them. If
18:47
nothing works out and if you know your fluid is that much tricky then maybe you
18:53
might need to go for a dualported design. Otherwise if it's high DP you should go for a cage guided design is a
18:59
better choice. The balanced and the unbalanced trim design and then we will you know club all of these trims
19:05
together and try to make a you know kind of like an algorithm. So now here when I'm trying to talk about balanced or
19:12
unbalanced design if you see here this is the plug this is the seat assembly available and this is the fluid forces which are hitting to it. Now what is
19:19
going to happen is the fluid forces let us call it is P2 and the actuator force is P1. I want the valve to be closed P1
19:27
has to be greater than P2 which makes sense right? If actuator force is greater it is going to close and not
19:33
allow the fluid to enter. This means the actuator has to put all the power. When
19:38
you go for a balanced trim design, if you see there's this small hole here,
19:43
what does this small hole do over here is at this particular portion is that once you have that hole available, the
19:49
fluid forces can enter through the hole and go to the opposite side. Once they go to the opposite side, the actuator
19:56
and the fluid forces become friends with each other. And it's kind of like they'll further support and allow the
20:02
force to add up. For example, the fluid force was P2 and on the other side you have actuator force P1 plus P2 acting
20:10
from the opposite direction. So this greatly reduces your load on the
20:16
actuator. When is this design good? It is good when you have very high DP or
20:21
your line size is too large. Because if your line size is too large, your actuator sizing will become again big.
20:27
So either if your DP is too high. So even if the line size is small but the DP is extremely high, you should still
20:33
go for a balanced trim design. Why? Because it will save a lot of your cost
20:39
in terms of the actuator sizing. But again, there is a big butt. The reason
20:45
is if your fluid even has smaller solid particles still they'll get stuck in
20:51
your balancing hole and your actuator will not be able to function well
20:58
because it is not designed for that high pressure. Now why am I telling you this is a lot of times what happens as
21:04
engineers is you give a requisition for a particular vendor the vendor will
21:09
definitely has to save cost. He would not see any clause maintained in your data sheet saying that there is going to
21:16
be some solid particles. You miss to mention that clause and he gives you a balanced design. Now when it gets to
21:22
plant your valve will actually that hole will get stuck and your valve will not
21:28
function properly. It will not close and you will have extremely high leakage rate. First thing. Second thing is if
21:35
you can see my mouse here once the fluid enters here at this particular point again there's going to be another
21:41
leakage path available. So your leakage chances also increases. So again you
21:47
need to be very cautious that are you okay to have slight amount of leakage available here. Now let us look into the
21:54
trim selection chart. So first you have to see which I told you initially a
21:59
friend of mine has always been an advocate of DP. So if the DP is high or not, DP is like one two bar is like very
22:07
minimum. As the DP increases 50 bar, 100 bar, you have to understand how is the
22:13
DP. Once you know that, then you look for is the line size large. If the line size is also not large, then you should
22:21
go for single port plug guided. Plug guided means the plug itself is contoured to that level instead of cage
22:27
guided. You might go with plug guided should be okay for very small size. the DP is also less. Go for that. Save your
22:33
cost. If that is not possible, if your DP is very high, then you see whether the
22:41
service is clean or not. Because if your service is dirty service, even if you
22:47
have something like unbalanced trim or you know cage guided then you have to look how dirty is the service. If your
22:53
service is clean, the answer is yes and your line size is also large, then you
22:59
should prefer to go with a balanced trim design with a cage guided design. So
23:04
inside the cage guided with a balanced trim is your best choice to go. If your service is extremely dirty, it has very
23:12
hard and strong particles which are there. In that case maybe you might have
23:17
to go for a dualported valve so that the valve stays in its you know position at
23:23
very high DPS and it has a lot of dirty fluids. It still should be able to handle it. But this side can be
23:29
discussed with your valve vendor and people can come together and find if there is some other solution. If not
23:36
then maybe you might have to go for a dualported design. Now in this algorithm what we have yet not considered is the
23:43
characteristics whether it's going to be linear equal percentage or quick opening. So now let's look at only that
23:49
part. What maybe give you a golf example to make that point is example if you see here I need to reach to point A1 which
23:56
is the winning point. Okay. And you have B1 and C1 two different points for you know hitting the golf ball. Whenever I
24:02
hit a ball to reach to A1, there is wind which acts and causes my ball to fall in
24:08
B1. So now what is an engineer's mind here? You can't control the wind.
24:14
But you can definitely control your stroke and your ability. So what do you do is you aim for C1. So you know that
24:22
as soon as I aim for C1, eventually the wind is going to come which is a
24:27
uncertain factor but to kind of extend you can you know manipulate. Okay fine you Okay, it causes your valve or your
24:33
basically ball to move 10 cm behind and then you get to A1. So basically you try
24:39
to understand how the nonlinearities of wind works and then eventually you get to your point. This is the same concept
24:47
when it comes to your valve characteristics. There's lot of different literature available when it comes to your characteristic selections.
24:53
A lot of people have their different opinions. I respect all of them. This is what I personally find it to be valuable
25:01
and what I usual use. I'm sharing it with you and I will al also explain the concept. Then it is on to you to decide
25:08
of how you want to select your characteristics. They mention something called as delp max by delp min which is
25:15
under the ratio of 2 is to1 or higher. So the overall concept is very simple. The concept is that if you have
25:22
variations in the db ideally you are expecting your valve to be linear.
25:27
Everybody wants the valve to be but because you can't control the DPS in the plant because they are continuously
25:33
fluctuating. If the DP variation is high which you see on the right hand side here the percentage selection should be
25:40
usually be equal percentage there. If your DP variation is less in and of
25:45
itself you should usually go for linear. However, there are certain people who recommend certain type of
25:51
characteristics based on application. We will also look into that point. So for trim characteristic selection I would
25:58
say is the DP fluctuating? Is it greater than 2 is to1? Is it fluctuating? No.
26:03
Then go for linear characteristics is usually recommended. Then if your DP fluctuation is higher you should go for
26:09
equal characteristics. Most of you people who are working you might have selected equal percentage
26:15
characteristics. Sometimes it is just because you found in some other data sheet and you copy and pasted the same
26:21
data which is not correct. But most applications are tricky for us. But when
26:27
it gets to applications, we can also have this thumb rule that you know usually level applications are kind of
26:32
simple. So usually you might see linear mentioned more there most of the times.
26:38
When it comes to flow or pressure applications, these are kind of fluctuating a lot. So usually you will
26:44
have equal characteristics trim mentioned here. But I would say go with this rule of 2 is to 1 and 5 is to1.
26:51
Less DP fluctuation go with linear. High DP fluctuation go with equal percentage.
26:56
Third important thing is material selection. I have got a lot of questions
27:01
from engineers asking about material selection. First before we select is to know how the
27:07
materials are actually named in their way. For example, when you see unsing system, you see something like this
27:13
mentioned here where this is your main material and this is your subgrade. Now this subgrid will vary. For example,
27:19
316L you have 03 written in the end. So some vendors give you materials mentioned in this format. Sometimes you
27:26
might have something in the AM format. Here you would have is like this grade which is the uh let's not answer first.
27:33
You have these two grades available here which is actually nothing but 316. One is the forged grade and one is the cast
27:40
grade. The forged grade is something which you beat up and then you make it. Cast is where you cast it into a mold.
27:46
it gets cold and then that's how you get the material. Now why has ASM done this is because you have more grades also
27:54
with ASM but the reason is that forged grades are generally considered to be
27:59
very hard compared to the cast version as an engineer. Why I stressed this
28:06
point is I would not name but after talking to few vendors there are certain
28:14
companies for a certain valve material they want it to be forged. So if the
28:20
vendor has given the cast version of that valve the valve body it was rejected and at a very later stage. So
28:28
the vendors be be very cautious if the vendor gives you unans numbering system of the material. You don't know whether
28:34
it is a cast grade or it's going to be a forge grade. And there are certain I'm
28:39
talking about worldrenowned companies that could reject by saying that no they want the forge grade and that is what is
28:46
specified in their specification. So be very cautious of this point as well and that is the reason why I put this here.
28:52
So both of these stand for nothing but 316. That being said, the DIN is another
28:58
uh numbering system which is kind of like more confusing. Oh, 1.4401 has nothing to do with like 316 mentioned
29:05
anywhere near to it, but it is the 316 grade and in the end if it ends with 04 it's 316 L. So again in this you don't
29:12
know whether it is forged or cast. So first thing is you should know if your
29:17
application is requiring which kind of material and I would like to give you some thumb rule. If your line size is
29:24
small, vendors can give you forged version. If your line sizes are too huge, they it is difficult for them to
29:32
give you forged version. If it is still mentioned in your spec that they want a forged version, then you should
29:38
definitely raise this. I would say leniency here when it comes to very large sizes. Now, in terms of materials,
29:44
as you said, it depends on particular service. I would also like to add like a chef who puts rices to make a particular
29:51
food. You need to know at least the basic components and how do they fit in when it comes to your application. So
29:58
you have chilies, you have pepper, you have something. If you want to make something spicy, you will add more chilies into it. If you want to make
30:04
something sweet, you would add sugar into it. When you mix something in a food, how its taste changes? Similarly,
30:11
when you mix something in a material, its composition is going to change. Now getting to your question that if the
30:18
pipe metal is mentioned something like 13% chromium CR can I select SS 316 I
30:24
would want to answer this after we get maybe to the end of this part. So the first thing here is I would compare
30:32
chilies to be like carbon you know the more you provide the more hotter the
30:38
food gets. Similarly carbon makes the material harder. The more you provide carbon, the more the material becomes
30:45
harder. That means if I want to have an applic So that is why you would see a
30:51
lot of pipes of piping are made of carbon steel especially. Okay. One thing
30:58
is as these things become harder, they'll also become brittle at the same time. Example is glass. Glass is hard
31:05
but if I break it, it's very easy. It's brittle. So I can't keep adding carbon all the time. Similar to chilies, I
31:12
can't keep adding chilies to make the food spicy. At a point of time, it becomes unbearable. Second thing is why
31:18
is this carbon thing important for you to know is if you imagine carbon steel line and if you have SS 316 valve body,
31:26
so you might be more corrosion resistant than that. But if you go to your flange
31:33
ratings, they will be inferior because they are not as hard because carbon steel is harder. So maybe you might have
31:40
to up your ratings. So that is how you should have an in-depth understanding that okay I don't have carbon in my
31:46
valve so my body rating and the flange rating will be higher to match that of
31:52
carbon but corrosion resistant wise I am better than carbon. SS316 is better. Why
31:58
it is better also we will get into that. But so remember carbon is what personally I remember it as the chili.
32:04
Use it as much as you want but at a point of time if it becomes too much
32:10
carbon it's going to make your very uh you know your material to be very hard. The second one which comes in as
32:16
sprinklers is going to be chromium. Very important. The higher the chromium the
32:22
higher the ability to prevent corrosion. So when you have any carbon steel pipe
32:29
and a stainless steel pipe almost every one of you will answer that carbon steel
32:34
pipe compared to SS 316 the 316 will have higher corrosion resistance very
32:41
simple the reason is because we have put chromium into it now now let's answer
32:46
that question so if the piping has 13% chromium is the pipe material as an
32:51
engineer if you select SS 316 the chromium percentage it is very easy you can check it online also and you have
32:58
the standard ASM standard also has it very clearly defined how much percentage of chromium is required it is 18%. So
33:06
you are higher in the chromium side. So you should hopefully be good with the fluid. You are more corrosion resistant.
33:13
However, be very cautious of the rating. Could be that your rating might be inferior and you might for example from
33:19
300 flange rating you might require it to be 600 flange rating or 900 flange
33:24
rating depending on that. However, fluid wise you are good to go. Next component which comes in is going to be nickel.
33:31
Now nickel what it does is it adds stability at high temperature. Most applications especially for
33:38
instrumentation you would see SS316. The reason is it has nickel, it has
33:44
chromium, it has carbon. So it is comparatively hard. It has good
33:49
corrosion resistance and because of nickel it has stability at high temperature. So for most applications
33:55
you will see SS 316 being good. But that does not mean every single application
34:02
if your fluid is okay, if the piping material is carbon steel, if you don't
34:08
need any high, you know, especially high temperatures are not there, corrosion is not going to be there, then I prefer go
34:14
with a carbon steel body. You will save a lot of cost. One more thing I want to add up here is whenever you look for
34:20
this is for a bit experienced engineers. Whenever you look for piping material specifications, you always see something
34:26
called as corrosion alloance. If you select your valve material same as the pipe material which is carbon steel.
34:33
Then what you need to be cautious also is that pipe material also has a bit
34:38
allowance for corrosion because pipes are going to be for kilometers also. So you can't always have superior metals.
34:45
So what they do is they increase the thickness a bit that let the pipe corroded. So there's something called as
34:50
corrosion rate per year. So the corrosion allowance is for example 6 mm or 10 mm. So that much area can get
34:57
corroded and still the pipe is going to work well. If that is the case and if the corrosion allowance limit is high
35:04
then remember if your valve body is also of the same material then I think it's a
35:10
risky engineering decision. If the corrosion allowance is low, yes, you can go ahead with the same material because
35:15
our standards don't have like the API standards don't have any specific clause or at least I have not come across any
35:22
clause which talks about corrosion allowance in our walls. So whatever is the thickness is the thickness we
35:28
assume. Another important thing is the trim material according to me. Do not be
35:35
stingy on the trim material. Select the best because the trim is going to experience highest amount of velocity,
35:42
DP everything. So the trim material should be at least same or higher than
35:48
that of the piping valves and on trims we will go in depth hopefully in coming sessions but definitely that material
35:55
selection is very very critical. Third thing important for you is when it comes to high temperature is if you select
36:02
dissimilar metals. If the trim is of a different material than that of your plug or your stem
36:09
each component has its coefficient of expansion due to heat. If they have
36:14
dissimilar at very high temperatures I'm talking about something like 600° 800°
36:20
something of that level. There are certain applications which require such high temperatures. There you have to be
36:26
very cautious of if you're selecting dissimilar metal you can have extra stress which can cause the stem to break
36:32
or some other issues can happen in the plant. Soft packing material. Okay. Now packing material is something which is u
36:40
a little bit more uh trickier than this. I'll just give you thumb rules right now cuz we're running short of time. See uh
36:46
for packing material you need to see the fluid also. At the same time temperature becomes very important. And third is
36:53
which may mentioned fugitive emissions. Overall speaking packing wise low temperatures 200° 250 degree go for PTFE
37:01
goes higher temperature 400° so go for graphite. If you have um fugitive
37:07
emissions usually start with first is you know vtype design live loading
37:13
design if not possible only then you start to go for bellows. It is the worst
37:18
case scenario. If nothing works, your fugitive emission is extremely high which is class A, then only you should
37:25
think for a bellow. I'll just quickly wind up with just giving you at least the basic international standards. These
37:30
are not all. If possible, I'll try to share maybe an Excel or maybe a list of
37:35
all these standards, all the important ones. But here I'm just sharing is uh which are at least basic and crucial
37:42
required. First is the valve C2C distances. Okay, here remember that ASME B 16.10 10 is one very important
37:49
standard that your valve manufacturer should usually follow. The reason is
37:55
piping will not wait for your valves to get manufactured. So they will have certain distance that they need to keep
38:01
between two pipes. Why am I sharing this is in few of my experiences I have learned is especially if you are g
38:09
offers or basically you are inviting newer vendors who have come into the field they sometimes don't comply with
38:15
this faceto-face dimensions and at the site it will be a big hassle for you if
38:20
you cannot match in between the two piping flanges. So first thing is if you have a new vendor if it's a reputed
38:27
established vendor they usually follow asp.10 content or it's there also an ISA standard which gives you the faceto-face
38:33
dimensions. Um I can't go in depth right now but when it gets to your RTG and
38:39
those designs when the plans there you have to be a little bit more you need to calculate it exactly if it's a new
38:45
vendor that you know is he complying with the facetoface requirements or whatever is mentioned in your project.
38:52
Second thing, if your valves are special, okay, I don't know if uh if you
38:58
have experienced this, but if there is some modification or it's a special kind of valve, then sometimes it will not
39:05
comply with this face-to-face dimensions. So up front you need to take the dimensions from the vendor and give
39:11
it to your piping department or else later you will suffer when the pipe when the valve is manufactured. So this
39:18
interface has to be very wellnown. Next after that is going to be your FL
39:23
standards. This is ASMBB 16.34. If you look in this standard as maybe
39:29
16.34, it has various classes. Standard class, special class. Usually 99.9% of
39:36
your projects will be going with the standard class. Check the PT rating based on your standard classes. As
39:42
somebody said, if your pipe material was carbon steel and your valve is 316 L, so
39:49
probably it might not have the same rating. So your rating will increase and similarly the pipe rating has to be
39:54
increased to match the valve with the pipe. Now this is something which a lot of people get confused with. You also
40:00
have API valve standards for example API 623 for globe valves or API 609 for
40:07
butterfly valves. The point is should I follow 16.34 or should you follow the
40:12
API standard is one query which comes in overall speaking if you have API 623 for
40:20
example it is more stringent compared to 16.34 overall so if that is the case
40:27
then if you have already specified API 623 then you are at uh a stringent
40:32
requirement so okay fine makes sense if you have specified 16.34 but your client
40:38
wants it to be an API valve which is usually for the petroleum and the oil and gas industry. You need to
40:43
specifically mention to the vendor that you need a valve which is manufactured as per the API standard as well. It will
40:50
not be covered under ASME. For example, the stem thicknesses for a globe valve is higher. So that is how those things
40:57
have to be definitely taken into care. Third is which a lot of you mentioned is the leakage class. Leakage class I told
41:03
you one important point. The leakage class mentioned is based on standard conditions. If your valve requires
41:09
extremely high amount of tight shut off, do not rely on control valve. Husky
41:14
accident happened. Even the Exxon mobile accidents have happened a lot where the control wall could not actually close
41:21
because and if you also read the API uh RP 553 which is also what we'll mention
41:28
soon in that also it is mentioned especially for flu uh FCC units. This is
41:34
a very common mistake that used to happen. Please avoid that. For uh fugitive emission standards ISO 15848
41:41
tough here uh something for you to know is in ISO 15848 you have -1 and -2. So
41:48
one of is where you do an actual testing of all the valves certain things where
41:55
you have just type testing. So you basically test a particular valve and that is basically suitable for all the
42:00
other valves. Taloft is basically very yet wellnown. It is uh usually used in
42:06
German projects. When you specify ISO5848, this standard itself is further divided.
42:13
Divided in the sense if you read the standard, it has three classes A, B, C.
42:18
A lot of the times engineers just mention the standard and you should check in your specs, do they want a
42:25
specific testing? Do you want it to be a H class or AB or BH class or C class? So
42:33
H stands for whatever is the thing. If you're using helium for whatever is a test gas that you use. So basically you
42:38
have ABC. So if you don't mention my understanding is vendors would consider
42:44
C which is the least stringent which makes sense if you have not mentioned they will consider C and if you wanted A
42:50
and you say later then it will be a big confusion because this testing is not very cheap. it is a good process and if
42:57
all the valves have to be tested if you go for that then that is not easy that being the case be very cautious when you
43:04
mention these standards second thing is the valve testing and I would I wanted
43:09
to cover calculations but I was assuming we'll run short of time so basically here uh I'll just mention is IS75 which
43:16
has further divided into like cavitation and uh cavitation index and all of those things will come here and for control
43:23
valve noise three and four I think three stands for gas and four stands for liquid. So the noise calculations have
43:31
to be done. This is just an overall overview which I'm giving. And then you have is your API RP553. I definitely
43:38
recommend you to read API RP 553. You will learn the recommendations for
43:43
fluid cracker FCC units etc. what you should do in those cases. So this is
43:48
just an overview. I'll try to add up more standards also as we go and then share with you the uh the presentation.
43:56
If I've made some mistakes while speaking, please forgive me. And uh thank you so much for your patience to
44:02
listen. [Music]