NDT- Non Destructive Testing

Nondestructive testing - NDT - use test methods to examine an object, material or system without impairing its future usefulness. Non-destructive testing is often required to verify the quality of a product or a system. Commonly used techniques are

AET - Acoustic Emission Testing

Acoustic Emission Testing takes advantage of the sharp sound that PCCP emits when it breaks or slips to identify areas of active distress within a construction. AET can be used to verify the structural integrity of pressure vessels, spheres, high temperature reactors and piping, coke drums, above ground storage tanks, cryogenic storage tanks and more. The inspection is executed externally and shut-down of the process may often not be necessary.

ART - Acoustic Resonance Testing

After an impact a specimen will vibrate in certain characteristic modes and frequencies that can be measured by a microphone or laser vibrometer. Acoustic sonic and ultrasonic resonance analysis is a non-destructive testing technique that allows testing of a wide range of test objects. Typical detecting faults are cracks, cavities, detached layers, material inconsistencies, hardness deviation in materials.

Utility Piping | Steam Piping - Steam Heating

In Previous Article We seen the different use and types of steam.

We know the dry saturated steam is generally used in pipe heating process.

Steam is one of the most common and effective heat transfer mediums used in industry, but it is not the only medium available. Other fluids such as hot water and oil are also used for indirect heating in heat exchangers.

So following are the advantages of steam heating:

In case of heating with hot water it only loose sensible heat around 17kcal/hr But if we use dry saturated steam then it loose latent heat around 539kcal/hr.

So we can see the use of the steam is more preferable in case of pipe heating.

Utility Piping | Steam Piping - Basic Of Steam

What Is Steam

In  a simple word Steam is the gas formed when water passes from the liquid to the gaseous state.

The process of formation of steam can be explained as,

In liquid water, H2O molecules are constantly being joined together and separated. As the water molecules are heated, however, the bonds connecting the molecules start breaking more rapidly than they can form. Eventually, when enough heat is supplied, some molecules will break free. These 'free' molecules form the transparent gas we know as steam, or more specifically dry steam.

So there are main two form of the steam: Dry steam and wet steam 

Steam is Called Dry steam when all its water molecules remain in the gaseous state. It's a transparent gas.

And is called as Wet Steam When Is Contain water particles in it. 

Because there are various form of the steam so according to the phase of steam use is different.

Cooling Tower

Cooling tower are very important part of many chemical plants. primary task of cooling tower is to reject heat into the atmosphere.

Cooling Tower Type:

Mainly there is two type : Natural draft and mechanical draft

Natural draft cooling tower are large in construction and mainly use for water flow rate more than 45000 m^3/hr.

There are three arrangement in mechanical draft:

1. Counter Flow induced draft

2.counter flow forced draft

3.cross flow induced draft

Main component of cooling tower:

Frame and casing, fill, cold water basin, drift eliminator, air inlet, louvers, nozzles and fan.

Pipe Material For Pipe And Pipe Elements

MATERIAL SELECTION OF PIPING COMPONENTS

The first thing to be considered is the selection of suitable material for the service. The selection of piping material requires knowledge of corrosion properties, strength and engineering characteristics, relative cost and availability.
The   main process considerations  in the material selection are the corrosion properties of the fluid, the pressure temperature conditions of the service and the nature of the service.

The Piping Designer selects/designs the piping components based on the mechanical properties  such as the following.

Heat and Mass Transfer Interview Question

Following are the three way of heat transfer:

Conduction

Convection

Radiation

What is Fourier law of heat conduction?

Concept of critical thickness of insulation.

What is Fin? Where it is require and why?

Heat Transfer By convection.

Free convection and force convection.

Newtons law of cooling.

Thermal Boundary layer.

What is Difference between free and force convection.

Fluid Mechanics Interview Question

Fluid mechanics is the science which deals with the fluid in rest or in motion.

It can be classified in static, kinematics and dynamic.

Fluid static deal with fluid at rest.

Fluid kinematics deal with fluid in motion without considers any pressure effect.

In Fluid Dynamics Fluid is in Motion and pressure effect is consider.

Following are some question which can be ask in Interview.

What are the different between liquid and gases?

Property of the fluid:

Density, Specific Weight, Specific Volume, Specific Gravity, Dynamic Viscosity, Kinematic Viscosity

What Is Newtons law of viscosity?

What are the changes in viscosity with temperature?

What is Cohesion, Adhesion and Surface Tension.?

What is Bulk modulus of elasticity?

What is pressure head? And what are the different types of pressure?

Which is the pressure measuring instrument?

What is buoyancy? Condition for equilibrium of floating Body.

What are the different types of flow?

Explain steady and unsteady Flow, uniform and non-uniform flow, Laminar and turbulent flow etc.

What is the use of Bernoulli Equation?

Basic Of Steam Turbine

The steam turbine is universally used as prime mover in steam power plants.

Flow over Blades:

The steam turbine obtains its motive power from the change of momentum of a jet of steam flowing over a curved blade. The steam jet, in moving over the curved surface of the blade, exerts a pressure on the blade owing to its centrifugal force. This centrifugal force is exerted normal to the blade surface as shown in figure and acts along the whole length of the blade.

The resultant of these centrifugal forces plus the effect of change of velocity is the motive force on the blade. It should be realized that the blade obtains no motive form any impact of the jet, because the blade is so designed that the steam jet will glide on and off the blade without any tendency to strike it. In principle, it is analogous to a train passing around a railway curve. The train exerts a radially outward force on the line due to the centrifugal force.

Moving and Fixed Blades

In a steam turbine, a number of small blades are fixed to the ring of a revolving wheel or rotor. Jets of steam of a high velocity are obtained by expansion through nozzles and are directed on to the blades. The effective force of these jets, acting on the blades, rotates the wheel.

In modern turbines several of the wheel of moving blades are keyed to the same shaft, having a ring of fixed blades between each wheel of moving blades. These fixed blades are fixed to the turbine casing. Their object is to receive the steam jet from the moving blade ring and to divert it on to the next ring of moving blades by changing its direction as shown. This diversion may continue over several rings of moving and fixed blades until the whole of the kinetic energy of the steam jet is expended.