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How to Estimate Total Capital Cost of Flare System Part 1 – Estimate Equipment Cost

Rifka Aisyah Leave a comment

In this post I want to share how to estimate total capital cost of flare system. Since the post is quite long, I will divide it into 3 posts:

  • Part 1 will explain how to estimate equipment cost
  • Part 2 will explain how to estimate installation cost
  • Part 3 will explain total capital cost

In the last part, I will also post a free spreadsheet on how to estimate capital cost of flare system described in every post.

For disclaimer, the accuracy of this cost estimation is ±30% (study estimate). Apply for tip flare tip diameter ranging from 1-60 in and stack heights ranging from 30-500 ft. Standard construction material is carbon steel.

The cost is based on 2017$ basis.

Flare system equipment cost
How to estimate total capital cost of flare system

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How to Estimate Gas Specific Gravity

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In this post I want to share how to estimate gas specific gravity.

What is gas specific gravity?

Gas specific gravity refers to the ratio between the density of a gas and the density of air at standard conditions (1 atm pressure and 60°F). When assuming ideal gas law behaviour, it equals the molecular weight of the gas divided by that of air.

What is the importance of gas specific gravity data?

Gas specific gravity data is frequently utilized in chemical engineering design processes. For example, gas specific gravity data is used to:

  • Predict natural gas hydrate formation temperature
  • Design oil and gas equipment
  • Assess the expected behaviour of gas when a leak occurs in the pipeline.
  • Etc

How to Estimate Gas Specific Gravity?

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How to Estimate Wind Speed as Function of Height

Rifka Aisyah Leave a comment

In this post I want to share to you how to estimate wind speed as function of height. Wind velocity plays a significant role in influencing the dispersion of released fluids. Wind speed rises with altitude above the earth’s surface, so reference height should be specified. Typically, 10 m is used as the meteorological standard unless noted otherwise.

Wind speed is also a function of weather stability and on the terrain.

Weather stability relates to vertical temperature gradients and atmospheric turbulence. The Pasquill-Gifford (P-G) classes are commonly used, with class G excluded from dispersion modelling. Read More

Process Safety Fundamentals: Learn Important Terms to Characterize Fires and Explosion

Rifka Aisyah Leave a comment

I plan to post more about process safety fundamentals in the future. In this post I want to share about process safety fundamentals which is important terms regarding characterization of fires and explosion.

Disclaimer: I am not a process safety expert. I am still learning about process safety topics. So, your feedback is appreciated. 

Based on statistics, the main cause of accidents in the chemical industry is fires and explosions. To prevent fires and explosions, we need to:

  • Learn the basics of fires and explosions
  • Conduct experiments to assess flammable and explosive materials
  • Implement these concepts in plant operations effectively

Understanding the basics of fires and explosions begins with familiarizing yourself with key terms related to these phenomena. You will learn through this post. Read More

Learn About Closed Drain Systems and How to Design

Rifka Aisyah Leave a comment

In this post I want to share to you about closed drain systems and how to design them. You may know several types of drainage in process plant, which are:

  • Closed drain
  • Open drain
  • Oil drain
  • Water drain

This post will cover about closed drain system. Hopefully in the near future I share to you other types of drain.

What is closed drain system?

During maintenance activities, process liquid in the equipment should be emptied. The liquid must be collected. The volume of collected liquid can be significant, therefore must be recovered and can be reused in the process or disposed safely.

Closed drain system is facility used to collect the liquid from the bottom of vessels and their associated piping to a recovery vessel or closed drain drum or closed drain vessel. The liquid flows to the vessel or drum by gravity. Read More

Fail-Safe Position Selection of Control Valves (Part 2)

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In this post I want to share several examples of fail-safe position selection of control valves. I posted about this topic a long time ago. You can also check the post.

A control valve consists of valve body, trim, or stem, plug and seat, and an actuator. The valve body consists of an orifice through which the manipulated variable passes. The trim or stem is connected to the diaphragm and the valve plug that can be in the form of a ball, a disk, or a gate. The valve seat offers a tight seal for a valve shutoff position.

Schematic of control valve
Schematic of control valve

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How to Easily Estimate the Time Needed for the Vessel to Collapse

Rifka Aisyah Leave a comment

In this post, I want to share to you how to easily estimate the time needed for the vessel to collapse. The equation involves several simple and basic equation, such as conservation principle and adiabatic compression equation. Let’s dig into the example.

There is a thermally insulated vessel initially at atmospheric pressure and partially filled with water. The vessel is fed with additional water at a constant flow rate of 2 m3/h. The air contained in the vessel headspace is compressed as the additional water is fed. The vessel can withstand a maximum pressure of 3 atm absolute. Read More

Applications of Globe Valves and Their Examples

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In this post, I want to share with you the applications of globe valves and their examples. Different from ball, plug, and gate valves, which are used to start and stop fluid flow in piping systems, globe valves are used to regulate flow. Globe valves usually should not be used for less than 20% opening for throttling, because it will increase the wear and load concentration on the seat and plug.

Application of Globe Valves for Control Valves Bypass

Typical application of globe valves is for control valves bypass. When control valve is taken out for maintenance purpose, a bypass globe valve provides continuous operation with some level of regulation. Read More

Applications of Butterfly Valves and Their Examples

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In this post I want to share with you the applications of butterfly valves and their examples. A butterfly valve can stop, regulate, and start the fluid flow. Due to its ninety-degree rotation of the handle and the disk, the valve is quickly and easily operated.

Butterfly valves offer many advantages over ball, gate, globe, and plug valves, such as lower cost, less weight, less space requirements, and lower maintenance cost. The maintenance cost is relatively low because of few moving parts.

Butterfly valves are usually selected for utility services and low pressure gas services, with pressure class 300 and lower.

Applications of Butterfly Valves and Their Examples
Applications of Butterfly Valves and Their Examples

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Application of ball valves and their examples

Applications of Ball Valves and Their Examples

Rifka Aisyah Leave a comment

In this post, I want to share with you the applications of ball valves and their examples. In my experience, many oil and gas projects use ball valves a lot. What are the advantages and disadvantages of using ball valves, and what are their applications?

Ball valves are frequently selected for process and aggressive services containing hydrocarbon oil and gas. Ball valves are used for on/off purposes only, not for flow control (throttling). Read More