Part 2

Some Tips and Notes (2)

Advantages of reduced bore valve over full bore valves

Reduced bore valves have a smaller ball size than full bore valves and consequently the body (casting or forging) is smaller for reduced bore ball valves. This results in lower construction costs and lower weight. The smaller ball size also results in lower operating torque and lower cost of the actuator for the valve. The pressure drop across a reduced bore valve will be marginally higher than for full bore valves.

Where pressure drop becomes very critical, full bore valves are supplied instead of reduced bore valves. Full bore valves are also supplied in special applications such as in pipelines to facilitate pigging and for hot tapping applications.

Piston check valves mounted in vertical position

Piston or ball check valve are generally used in small sizes up to 2 inches. The fluid flow forces the piston or ball away from the seat causing the valve to open. When the flow stops or reverses, the piston or ball returns to its, seat stopping the reverse flow. Piston check valves function properly when they are installed in the horizontal piping as gravitational force reduces the chance of the piston sticking in the open position. Though in some designs a light spring is provided to assist in valve closure, they are not recommended to be installed in vertical piping.

Symbols on drawings
On my website, in the Documents menu you will find symbols applied to Isometrics, Piping and Instrumentaton Diagrams (PIDs) etc. All symbols are taken from drawings that I have handled myself, but almost every client and engineering company uses their own symbols, and some, with the same description can be seen in multiple versions.
A standard for all these symbols, would perhaps be an option.

References to YouTube videos
On my website, you can watch videos made by others. Sometimes it happens that the link gives an error message because the owner of the video has made changes. All links to the relevant videos are regularly checked by me, but it can still happen that an error occurs. If that is the case, I would be grateful if you let me know, through this Link
Thank you

Pictures general
A lot of pictures on this website are photographed by myself. But there are also a lot of pictures I got through people I know and the World Wide Web. Pictures of others I basically give a caption where I found the picture with the corresponding website URL.

A standard for all these symbols, would perhaps be an option.

Relationship between gauge and absolute pressure

There are two reference points for measuring pressure. When the reference point is standard atmospheric pressure, the measured pressure is called gauge pressure and is written psig. When the reference point is a perfect vacuum, the measured pressure is called absolute pressure and is written with psia.

So, standard atmospheric pressure at sea level is 14.696 psia = 0 psia.
Perfect vacuum = 0 psia = -14.696 psia
Absolute pressure (psia) = gauge pressure + 14.7 psia

Steel beams in accordance with NEN-EN 10025-1/2
The difference between a HEA, HEB and a HEM beam is generally in the thickness dimensions of the three planes. But there are also substantial differences in the width and height dimensions. (In the past I once made quite a HEA mistake with the W - H dimensions, to assume something, while the reality was not the same.)

The link below will take you to the dimensions of the mentioned beams...
Dimensions of Steel Beams

Copper Steam Tracing
For pipelines equipped with copper steam tracing tubes and insulated for this reason, it must be ensured that threaded fittings used to mount the tubes are definitely not placed under the insulation.

The link below may tell you why...
Heat Tracing of Piping Systems

What is killed carbon steel?

Steel that has been completely deoxidized by the addition of an agent such as silicon or alumimium, before casting, so that there is practically no evolution of gas during solidification. Killed steels are characterized by a high degree of chemical homogeneity and ;freedom from porosity.

We say the steel is "killed" because it will quietly solidify in the mould, with no gas bubbling out. As a result, killed steel is dense in structure, uniform in composition, and not so segregative as other types of steels.

Background
During the steel making process, oxygen may become dissolved in the liquid metal. During solidification, the dissolved oxygen can combine with carbon to form carbon monoxide bubbles. The carbon is added to the steel as an alloying element.
The carbon monoxide bubbles are often trapped in the casting and can act as initiation points for failure.

How Killed Steels are Produced and Their Advantages
Formation of the carbon monoxide bubbles can be eliminated through the addition of deoxidising agents such as aluminium, ferrosilicon and manganese. In the case of aluminium, the dissolved oxygen reacts with it to form aluminium oxide (Alumina, Al2O3). The formation of alumina not only prevents the formation of bubbles or porosity, but the tiny particles or inclusions also pin grain boundaries during heat treatment processes, preventing grain growth.

Completely deoxidised steel are known as "killed steels".

They have a more uniform analysis and are relatively free from ageing.
For a given carbon and manganese content, killed steels are usually harder then rimmed steels.
The disadvantage of using killed steels is they often display deep pipe shrinkage.
Steels that are typically killed and are generally killed include..

Steels with carbon contents greater then 0.25%
All forging grades of steel
Structural steels with carbon content between 0.15 to 0.25%
Some special steel in the lower carbon ranges

Dead man's handle for a valve

A deadman handle is a spring return valve designed for applications where fluids need to be drained or sampled.

The valve can be opened by the operator, but once the operator releases the handle, it springs back to the closed position, automatically closing the valve. A deadman handle provides a safe, economical, and reliable way to automatically close manual valves.

ANSI B16 or ASME B16?
Often I hear individuals talking about ANSI flanges. Probably because a particular customer's system has never upgraded its own standards, or because an older plant has ANSI described on the flanges. For years ANSI has not been the American standard for flanges e.g. but has become an ASME standard.

Do you see the ANSI marking on the flange?

The link below can tell you more about that...
ANSI B16 or ASME B16?

Proper length of Stud Bolts
For the proper length of a stud you can use as a rule of thumb.. The free threads of the bolt above the top of the nut is equals to 1/3 times the bolt diameter.

Throttling function of gate valve

When a gate valve is opened, the area of the opening does not increase linearly with stem movement. That is, the flow velocity across the valve does not increase linearly with stem movement. When a gate valve is opened, fluid flows over the valve at high velocity, causing erosion on the disc and seats, ultimately causing leakage across the seats. In the partially open position, the valve disc is also sensitive to vibration. Therefore, gate valves are not considered suitable for regulating or throttling flow.

Parallel slide gate valve

Parallel gate valves consist of two discs with a spring mounted between the two discs. The discs are held lightly against the body seats by the springs to provide the initial sealing force. The springs do not provide the seating force. The upstream line pressure holds the downstream disc firmly against the downstream seat and provides the seating force. Parallel gate valves are used for applications with high pressure differentials or where thermal expansion can cause the gate to seize or block, such as in high pressure steam service.

Can Ring Joint Gaskets be reused?
Simple answer - NO
The link below will give you the answer to that...
Can Ring Joint Gaskets be reused?

How do you calculate the length of a Stud Bolt?
The link below will give you the answer to that...
Method for calculating Stud Bolt length

Difference between solid wedge gate valve and flexible wedge gate valve

The solid wedge gate valve is the most commonly used type of gate valve. The wedge is a one-piece construction that is machined to fit the body seat to provide a tight seal. The disadvantage of a solid wedge is that it is prone to seizing when there is slight deformation in the valve body due to thermal expansion or bending loads. The flexible wedge gate valve overcomes this limitation. In a flexible wedge design, the wedge is provided with an annular groove that allows the wedge to flex in the body seat. The flexible wedge can accommodate deformation in the valve body.

Height of Stud Bolt Nut
The height of a nut for a Stud Bolt ASME B16.5 and ASME 16.47 is the same as the diameter of the thread rod.

Height of Raised Face
In Pressure Classes 150 and 300, the height of raised face flange is approximately 1.6 mm (1/16 inch). In Pressure Classes 400, 600, 900, 1500 and 2500, the height of raised face is approximately 6.4 mm (1/4 inch).

Difference between NPS and DN Pipe Size

NPS stands for Nominal Pipe Size, and indicates the standard pipe size followed by the size designation without an inch symbol. For example, NPS 8 refers to a pipe with a nominal pipe size of 8 inches. For sizes 14" and larger, the NPS is equal to the outside diameter in inches..

DN stands for Diameter Nominal and is used in the metric system of units. DN indicates the standard pipe size followed by the size designation without a millimeter symbol. For example, DN 100 refers to a pipe with a nominal diameter of 100 mm. The equivalent designation is NPS 4.

Part 1

Part 2