Importance of CAD Knowledge in the Engineering World


It’s safe to say that computer-aided design, or CAD, revolutionized modern day engineering. CAD allows for the easier development of products and product management integration. It also allows for greater modeling and even provides a basis for virtual networking!

In the engineering world, CAD is extremely important and widely used to design and develop products to be used by consumers. This knowledge is a hot commodity for those employing engineers, because of its benefits in the engineering workplace.

CAD Drawing Benefits

CAD drawings offer the flexibility to draft and design in a digital sphere, which were previously done by hand. The digital format makes data handling easier, safer, and quicker. Prior hand drawn blueprints can be scanned and then can be expanded upon digitally. Many CAD programs are now using three-dimensional drawings to maximize productivity and provide quicker, better product results, allowing for the development of the tiniest details.

Project Management Benefits

CAD’s excellent ability for comprehensive documentation and communication allows for an easier product management environment. Team communication is simpler and less stressful due to the easy sharing properties. Engineers working in teams on complex projects can establish a CAD library, allowing for the storing and reference of certain projects.

CAD Networking

The information age has allowed CAD data to be shared throughout the industry, revolutionizing best practices. There are many virtual open CAD libraries providing a wealth of online resources for engineers.

Manufacturers can also supply CAD drawings of products for review before purchase in a way that could not be shared before, allowing for less travel and shipping.

Engineering professionals can also offer advice to the next generation of engineers. Online support is available through a variety of CAD networks.

The Texvyn Group can help you to develop a right Job Oriented Cad Skills. Contact us today for free career counseling & other job oriented courses.


Career in Chemical Process Design Companies


Chemical Process Design Companies play a vital role in bringing up new chemical industries and also provides solutions for retrofitting the old ones to increase the production level. This article helps fresh Chemical Engineers to provide an idea about various Chemical Design Companies and their services, Chemical Engineers job profile and skill set needed to achieve professional excellence. 

Services of Design Companies

 Chemical Process Design Companies carry out Technical and economic feasibility study, Technical audits, Performance and Optimization study, Engineering Procurement & construction, Project management etc

Basic engineering packages, Detailed engineering packages, HAZOP study, Operator training simulators are also developed as per the client requirement.

Most of the Chemical design companies have their own technology for manufacturing chemicals/ petrochemicals and so they provide Commissioning and start up assistance to achieve performance guarantee trial run of the plant.

Job Profile and Skill set Requirement

 Process Engineer, Heat transfer engineer require technical knowledge in Chemical Engineering along with Chemical Process Calculations. Hands on Experience in using Chemical Process Simulation software’s like Aspen Hysys, Aspen Plus, Chemcad PRO II, Unisim , Flarenet, and HTRI is an added advantage. Familiarity with standards like API, ASME, NFPA is also expected since Relief valve sizing, Hydraulics calculation, Equipment and line sizing  are also involves in the job of a process engineer. Shell Design Engineering Practices, Foster Wheeler Process Standards, Exxon Mobil Design Practices will also provide assistance in chemical process design.

Process Safety and Loss prevention engineer, Risk engineer roles require knowledge on Chemical Process Safety. Quantitative Risk Assesment – QRA, Process Hazard Analysis – PHA, Job Safety Analysis- JSA , Hazard & Operability Study – HAZOP are essential studies which is the part of safety engineers job. Softwares like PHAST, SAFETI is also used in their studies.

Startup Advisor, Training specialists & Technology Manager roles need troubleshooting skills along with chemical plant operating experience to excel in their job.

Good communication, negotiation and networking skills in Chemical Engineering conferences are expected for the jobs as Proposals engineer, Sales and Marketing engineer since techno commercial negotiation is the most sought part in their job.

Process Control Engineer develops operator simulator stations for their clients and helps in optimizing the process control philosophy of the plant. Familiarity with Process control systems like DCS, PLC, APC & ESD with logical reasoning skills will help to shine as Process control engineer.

R & D specialist involves in research study to bring in new technology and exploring better alternatives.

Exxon Mobil is one of the largest petrochemical companies in the world. Exxon Mobil holds the technology licensing for LDPE, EVA, PP, Paraxylene, Benzene, Phenolics and styrenics.

Axens is involved in Oil refining, Petrochemicals and Chemicals, Gases, Alternative Fuels, Water. Axens is recognized for its technology in BTX, Propylene, Paraxylene etc.

Headquatered in Switzerland, Casale is famous for its design and refurbishment of Ammonia, Methanol and Urea plants.

Netherland based LyondellBasell is a licensor for Poly propylene – PP & Poly ethylene – PE plants. Visit this interactive page about how products are used in day to day life.

Haldor Topsoe is a Denmark based company involved in Catalyst manufacture and process design and revamp of Ammonia and Methanol plants.

UOP – A Honeywell company, international supplier and licensor for the petroleum refining, gas processing and petrochemical plants. UOP technologies are used in Biodegradable detergents, Polyester and gasoline production.

KBR – A Texas based company employs around 27,000 people all over the world. KBR provides technology for Ammonia, Hydrogen, Coal Gasification, Carbon capture and storage, Olefin, Petrochemical Refining plants.

Some of the other leading Chemical Process Design companies include Technip, Saipem, Dow, Toyo, Linde, Lurgi, Stamicarbon, Lummus, Air Liquide, Uhde etc where Chemical Engineers have enormous opportunities to work with.

Hope this will help Chemical Engineers to land their dream job in Chemical Process design companies.

We at Texvyn Technologies, provide a unique training program which ensures young Chemical engineer 100% Job Guarantee**


Safety Valves


What are they?

‘A valve which automatically, without the assistance of any energy other than that of the fluid concerned, discharges a quantity of the fluid so as to prevent a predetermined safe pressure being exceeded, and which is designed to reclose and prevent further flow of fluid after normal pressure conditions of service have been restored’

Safety valves, as the name implies, have a specific function

to protect equipment & personnel

EN ISO 4126 only refers to safety valves & covers –

• Safety Valves
• Relief Valves
• Pressure Relief valves
• Safety Relief Valves

Why we need one?

4 main reasons –

  • Blocked Discharge
  • External Heat
  • Thermal Expansion
  • Failure of pipeline component, i.e. control valve


Set pressure :

The pressure at which the valves starts to open measured at valve inlet
normally 1.1 x working pressure or working pressure + 0.7 bar for water whichever is the greater.

Overpressure :

Pressure at which valve has to achieve its full discharge capacity normally set pressure +10%

Accumulation :

Pressure increase over the maximum working pressure of the system during discharge through the safety valve.

Operating states

There are 3 operating states for safety valves –

1. Equilibrium
2. Fully open
3. Fully closed


Blowdown :

The pressure difference between set pressure and pressure at which the valve reseats expressed as a % of the set pressure.

Reseat Pressure :

Pressure at which valve is fully closed.

Working Pressure :

Pressure at which the system being protected normally operates.

Discharge Capacity ;

The amount of water / gas/ vapour the valve will pass at a given pressure.

Equilibrium :

Forces acting to close are in equilibrium (balance) with the forces acting to open and the seat & disc are just in contact

>defined in EN ISO 4126 as the Set Pressure

>this is the point when flow is about to start

>in practice flow commences as the equilibrium point is reached

Fully open :

The position the valve must achieve to pass its rated capacity at its specified over pressure
note – this is not the Set Pressure
different designs of valve have different relationship between flow & pressure
some designs have a rapid increase in flow for a small increase in pressure -others offer a gradual increase.

Fully closed

the position when the valve has re-seated i.e. fully closed – nil leakage

the difference between the re-seat pressure & set pressure is often referred to as the Blowdown Pressure.

the blowdown pressure will depend on valve design, the faster the flow increases on opening the lower the blowdown pressure is


Underground Piping (U/G)

The piping system is taken underground generally for the utility services like cooling water supply to various units and cooling water return to cooling tower for line sizes normally 18 inch NB and above, other water services with big pipeline sizes, big oil supply lines and various sewer systems in the process units of the chemical, petrochemical and refinery type of plants.  The term “underground” applies to the piping – both buried or in trenches. The underground system consist of gravity flow drainage system carrying process waste, spillage, reclaimable hydrocarbons, sanitary and storm water, firewater and drinking water system.

Good engineering practice, local code / regulations, specific client requirements shall govern the design of the underground piping system in the plant.

The following are the common underground services in a chemical / petrochemical / refinery plants.

  • Cooling water (line size normally ≥18″ NB).
  • Fire Water.
  • Contaminated Rain Water Sewer from process catchment area.(CRWS).
  • Oily Water Sewer (OWS).
  • Liquid Effluent to the Effluent Treatment Plant.
  • Closed Blow Down system (CBD).
  • Sanitary system.
  • Storm Water.
  • Equipment drainage to slop tank.
  • Electrical cables.
  • Instrument cables

Type of Underground System

Depending on the service and the material that each system handles there are different system defined in the Underground system.Various underground systems can be described in the following way both for Utility system and sewer system.

Cooling Water System (CWS & CWR)

This is generally a buried system with protective wrapping and coating or with cathodic protection or both.

Any valve for isolation of a part of the cooling water system shall be enclosed in a valve pit. The normal compacted earth cover shall be 1200 mm over the top of the pipeline.  Theearth cover over pipe (back-fill) shall be compacted to at least 95% Proctor compaction Index to protect the pipe from aboveground loadings as per ASTM D-698.

Oily Water Sewer (OWS)

This system collects waste, drips and leaks from equipment and piping in areas that contain process equipment in non-corrosive services.  The layout engineer should consult the process engineer to fully identify all such equipment and provide a drain hub at each item.

The piping engineer should locate the oily water drain hubs using the above ground piping studies, setting each invert elevation and routing the line with relevant components / fittings.

Oily water sewer shall collect oily waste / drain from pump, equipment through funnel points and shall run with separate headers and manholes in the units.   The regular oil contamination areas shall also be segregated and discharge from these areas shall be collected in catch basins to be joined in oily water sewer.  Oily water sewer shall consist of carbon steel sewer, funnel points, clean outs, RCC catch basins, RCC manholes, vent pipes, flame arrestor etc.

Contaminated Rainwater Sewer (CRWS)

The areas which are contaminated due to floor wash drains etc. inside unit boundaries shall be demarcated.  Contaminated areas collected in catch basin shall be drained through CRWS while un-contaminated areas, normally at periphery of the units shall be drained through ditches covered with grating.

CRWS shall consist of underground carbon steel sewer with corrosion protection, funnel points, clean outs, RCC catch basins, RCC manholes, vent pipes, flame arrestor etc.

Open ditches of units should have a bypass either to the CRWS or to storm water, drains of offsite.

This system collects surface drainage from areas containing hydrocarbon – bearing equipment.  This water must pass through a treatment facility before being discharged into an uncontaminated system or natural body of water e.g. river or a stream.

Closed Blow Down (CBD) sewer

This system picks up drains around boilers and steam drums and is run as a separate system preferably to the battery limit.

The system shall be designed as per P&ID and the effluent collected from equipment through funnel points and underground piping system shall be connected to the underground CBD drum.

Amine Blow Down (ABD) sewer

The amine blow down system (ABD) shall be designed as per P&ID.

The effluent shall be collected from equipment through above ground points into close funnels connected to underground system.  The main header shall be connected to the underground Amine sump / drum.

Fire Water System

This system consists of a fire hydrant network around a process unit or equipment, with branches as required for hydrants or monitors to protect the unit in case of fire.

This is a close loop system starting from Firewater storage and pump to the specific location of hydrants and monitors.   This is always kept under a predetermined working pressure level.

Potable Water System

This water is used for drinking, emergency eye washes and safety shower facilities.

Sanitary Sewer System

Sanitary sewer system collects waste from all toilet facilities provided in various plants and non-plant buildings and shall be discharged to WWTP (Waste Water Treatment Plant)

Acids, caustics, hydrocarbons, rainwater or other chemical waste shall not be discharged to this system.

This system is routed to normally to a septic tank.

Underground Electrical and Instrument ducts

In the beginning of a project, the decision to route the major electrical and instrument conduits – above ground in the piperack or buried below grade shall be taken.

In case underground route is selected, electrical and instrument engineers shall be consulted for the optimum layout of ducts by the plant layout engineer.

Where conduits enter the unit through a pull box and cables come above ground for routing upto the terminal points, the space shall be kept free of piping, equipment or associated maintenance access.


Pig Launchers / Pig Receivers – Arrangement

Pig launchers and receivers are commonly used in upstream oil and gas industry for periodic cleaning of pipelines carrying crude oil, natural gas and water from oil wells. A pig is a bullet shaped object which fits the pipeline from inside. The pig launcher launches the pig into pipeline and the upstream pressure pushes the pig to other end of the pipeline where it is received by the pig launcher. Hence generally arrangement for pig launchers and receivers are essentially the same, except for the difference between ‘Kicker line’ position for launchers and receivers. The sample drawing presents this general arrangement common to pig launchers and receivers.


  1. Proper equipment symbol for pig launcher (vertical or horizontal) should be selected first of all, as shown in the presented drawing. This should be selected from the list of equipment symbols on the legend sheets of a particular project.
  2. The major and minor barrels of the pig trap should be indicated as shown in the sample drawing. Minor barrel size is equal to pipeline size and the major barrel size is slightly larger.
  3. All the nozzles on the pig launcher should then be correctly represented with size and flanges. This includes door on the launcher, pig outlet to pipeline, kicker line, balancing line, PSV connection, purge, vent, drain and instrument nozzles, as shown in the sample drawing presented here. Typical instrumentation on the pig launcher would be pressure gauges and transmitters and pig indicators to know if the pig has been launched (or arrived in the case of pig receivers).
  4. Different lines connected to the pig launcher are the next to be drawn up. Line number, material class, size etc. is to be correctly assigned to each of the lines.
  5. Kicker line is used to pressurize the upstream side of pig so it can be launched. In case of receiver, kicker line provides an outlet for fluids arriving in the pig trap. Normally when pigging is not being performed, kicker line is closed using normally closed valve.
  6. Balancing line connecting the kicker line to minor barrel of the pig launcher, helps lower the pressure differential so that sudden shooting of the pig will not damage downstream automatic valves.
  7. A bypass line of the pig launcher is the normal route for the fluids when pigging is not taking place. This section upstream to the shutdown valve at beginning of pipeline can be protected against overpressure as indicated in the sample drawing.
  8. The hand operated valve (HV) on the bypass line is used to create a pressure differential for launching the pig (also for receiving the pig). A pressure differential indicator (PDI) has to be available to the HV operator to monitor the pressure differential.
  9. On the outlet of the pig launcher, another hand operated automatic valve is provided to open up the launcher upon pressurization.
  10. The pig launcher (and receiver) are also protected against overpressure with a PSV which discharges to flare. Typical representation of PSVs can be referred to in another article.
  11. Isolation valves, spectacle blinds, spacers etc. to be used for maintenance should be drawn up next, on various lines to and from the pig trap. The spectacle blinds, spacers etc. are usually connected right next to the isolation valves and equipment nozzles, as indicated in the sample drawing presented here.
  12. Drains should be provided either on major or minor barrel or on both for complete draining of  the pig trap after the pig is launched or received. Sample drawing has indicated drains on both the barrels. These drains are connected to the closed drain system.
  13. Vents to flare and to atmosphere are required on pig launchers. Venting to flare for depressurization of the pig launcher can be achieved using bypass on the relief valve. For maintenance, when pig is not in operation it can be vented to atmosphere.
  14. A utility connection is required to purge the pig launcher / receiver after the pigging is done and the pig trap is depressurized and drained. A nitrogen connection should normally be provided as indicated in the sample drawing.
  15. Most of the guidelines mentioned for pig launchers also hold good for pig receivers.
  16. All the guidelines given here are very general and may be modified as per specific requirements of any particular project.


Introduction to Valves – Control Valves


Why Control Valves used?

Process plants consist of hundreds, or even thousands, of control loops all networked together to produce a product to be offered for sale. Each of these control loops is designed to keep some important process variable such as pressure, flow, level, temperature, etc. within a required operating range to ensure the quality of the end product. Each of these loops receives and internally creates disturbances that detrimentally affect the process variable, and interaction from other loops in the network provides disturbances that influence the process variable.

To reduce the effect of these load disturbances, sensors and transmitters collect information about the process variable and its relationship to some desired set point. A controller then processes this information and decides what must be done to get the process variable back to where it should be after a load disturbance occurs. When all the measuring, comparing, and calculating are done, some type of final control element must implement the strategy selected by the controller.

Principles of Operation

The most common final control element in the process control industries is the control valve. The control valve manipulates a flowing fluid, such as gas, steam, water, or chemical compounds, to compensate for the load disturbance and keep the regulated process variable as close as possible to the desired set point.

Control valves may be the most important, but sometimes the most neglected, part of a control loop. The reason is usually the instrument engineer’s unfamiliarity with the many facets, terminologies, and areas of engineering disciplines such as fluid mechanics, metallurgy, noise control, and piping and vessel design that can be involved depending on the severity of service conditions.

Any control loop usually consists of a sensor of the process condition, a transmitter and a controller that compares the “process variable” received from the transmitter with the “set point,” i.e., the desired process condition. The controller, in turn, sends a corrective signal to the “final control element,” the last part of the loop and the “muscle” of the process control system. While the sensors of the process variables are the eyes, the controller the brain, then the final control element is the hands of the control loop. This makes it the most important, alas sometimes the least understood, part of an automatic control system. This comes about, in part, due to our strong attachment to electronic systems and computers causing some neglect in the proper understanding and proper use of the all important hardware.

What is a Control Valve?

Control valves automatically regulate pressure and/or flow rate, and are available for any pressure. If different plant systems operate up to, and at pressure/temperature combinations that require Class 300 valves, sometimes (where the design permits), all control valves chosen will be Class 300 for interchange-ability. However, if none of the systems exceeds the ratings for Class 150 valves, this is not necessary.

Globe valves are normally used for control, and their ends are usually flanged for ease of maintenance. Depending on their type of supply, the disk is moved by a hydraulic, pneumatic, electrical or mechanical actuator. The valve modulates flow through movement of a valve plug in relation to the port(s) located within the valve body. The valve plug is attached to a valve stem, which, in turn, is connected to the actuator.

Control Valve Arrangement