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Recommended Safety Distance for Siting and Layout of Facilities

Facility layout is one of many document deliverables in a project. Do you know the philosophy to create facility layout? In this post, I want to share a siting and layout approach, as well as recommended safety distance for siting and layout of facilities by Center for Chemical Process Safety (CCPS) of the American Institute of Chemical Engineers (AIChe).

The siting philosophy begin with a review of the material and processing hazards, such as toxicity, flammability, explosivity, reactivity, or a combination of these hazards. Other potential hazards should also be considered since they may be unacceptable to their surrounding community, such as odors, loud noises, or the light from flares.

Once the type of hazards have been identified, their potential off-site and on-site impacts can be addressed. This step includes how the local terrains affects the release scenarios. At the same time, the layout of the process units and associated areas within the facility, such as storage tank areas or flares, should be arranged to reduce risks. The layout of the equipment, including both orientation and distance between them, may affect day-to-day operations. Therefore, it is important to address the balance between reduced or increased distances and the impact on accessibility when evaluating the on-site consequences. Read More

Pipe Wall Thickness Chart

Pipe wall thickness chart is a must-have item for me as process engineer. I usually use it when I have to size pipe, do hydraulic analysis, etc. Information I need from the chart are mostly outside diameter and inside diameter of particular pipe size.

In this post I want to share you pipe wall thickness chart based on ASME B36.19M-2004 Stainless Steel Pipe.

In this chart you can extract data of

  • Outside diameter and wall thickness in inch and mm
  • Pipe size is expressed in NPS (Nominal Pipe Schedule) and DN (Diametre Nominal)
  • Weight in pound per linear foot or kilogram per meter

Read More

PSV

Safety Valve vs Relief Valve (Differences based on API 521)

Sometimes terms can be confusing. Terms safety valve and relief valve are confusing too. So, to make it clear, let see the definition based on API 521.

Pressure relief valve is a generic term applied to relief valves, safety valves, and safety relief valves. It is designed to automatically reclose and prevent the flow of fluid.

Relief valve is a spring-loaded pressure relief valve actuated by the static pressure upstream of the valve. The valve opens normally in proportion to the pressure increase over the opening pressure. A relief valve is used primarily with incompressible fluids.

Safety relief valve is a spring-loaded pressure relief valve that may be used as either a safety or relief valve, depending on the application.

Safety valve is a spring-loaded pressure relief valve actuated by the static pressure upstream of the valve and characterized by rapid opening or pop action. A safety valve is normally used for compressible fluid.

Can you spot the differences?

Relief valve is used for liquid and open in proportion to the pressure increase, while safety valve is used for gas and open rapidly.

Reference:

API 521 Pressure relieving and depressuring system

 

Fail-safe position

Fail-Safe Position Selection of Control Valve

In designing a processing facility, we usually use control valve to manipulates the temperature, pressure, level, or fluid flow rate in process system. The selection of control valve, which is air-to-open or air-to-close, is base on safety consideration. In case of power loss or air failure , control valve should move in safe position (fail-safe).

Fail Position

Fail position is the term used to describe how control valve will react when there is loss of power. I read there are three different fail positions. Read More

Pipe Size Selection and Several Criteria of Pipe Size

Someone in my office asked me if there is a criteria for pipe size selection, in other words, pipe sizing criteria. One basic document that every process engineer produce in the beginning of engineering stage is process design basisIn the document, pipe size criteria shall be stated clearly.

I have involved in at least two engineering projects. Those two projects have different pipe size criteria. Which one is correct? Read More

Reciprocating Pump P&ID Configuration

Reciprocating pump is a class of positive displacement pump which includes piston pump, plunger pump, and diaphragm pump. It is often used where a relatively small quantity of liquid to be handled and where delivery pressure is quite large. Priming is not required because it is positive displacement pump. Reciprocating pumps have lower efficiency compared to centrifugal pump.

API 674 – Positive Displacement Pump – Reciprocating covers minimum requirements for reciprocating positive displacement pumps for refinery application. The standard also covers piping and instrumentation required for the pump. Read More

Piping Basics

I am getting a really nice and free piping bulk material training in my company. It is a really rare for me to get such training so I won’t let it pass without meaning. The training was actually intended for supply chain staff. Although I am not one of them, my boss let me participate in the training.

Five days ago was a second meeting. It was not as good as the first time because we started to learn technical matter although it’s only the basic. Since there will be a test and I don’t want to put my face on shame, I need to learn more to gain the same understanding as those supply chain staffs.

I just got a nice, simple, and understandable presentation about piping basics. I really enjoy the presentation and I hope you too.

 

Understanding Terms in Piping System Part 1

You always need to find a bright side of a simple task. For example, copy, paste, and modify piping material specification, specification for coating and wrapping, and piping design. Yesterday I did this! At the first time I thought this was a very ridiculuous task yet unimportant. I’ve ever seen a drafter did this. But I found a bright side of this task which is a chance to learn. 

My objective is very simple. I want to understand what other people are talking about, when piping is their topic. I want to undestand the terms and imagine what they are looked like. That’s all. I think this is a good step to learn about piping.

Piping system has a lot of terms. So, it is impossible to write and describe all of them. In this post I want to share a brief explanation about piping system. As long as I understand them, it’s oke 🙂 Read More

Where to install pressure gauge at pump discharge line

Yesterday I had enough time to increase my basic knowledge in chemical engineering because I had finished my works. Then, I stumbled upon this link and started to think about my piping and instrumentation diagram. I realized I had make a fundamental mistakes. I felt useless.

I am writing this post so that I will remember my mistakes and never try to do it again. Hope you find it useful.

Remember everyone! Pressure gauge shall be installed after pump discharge nozzle and before check valve. The consequence is if you have two pumps (one is running and another is stand by, then you have to install two pressure gauge). The reason is:

  • To show actual pump discharge pressure. If you install pressure gauge after check valve, the value of discharge pressure won’t be actual due to pressure loss of check valve
  • In the case of check valve failure, pressure gauge will show actual discharge pressure. If the pump has problem, pressure gauge will show pressure value lower than usual

Storage Tank Selection

In my recent project, there are at least eight liquid storage tanks we need to design and purchase. Although, the design of storage tank is not part of my work (it is a job of mechanical engineers), but I always wonder how people design the tanks. In this post, I want to share to you the results of my desktop study about liquid storage tank selection. Read More