21/11/2024
Engineering Stress-Strain vs True Stress-Strain Diagram
Key Differences:
1. Material Behavior:
Engineering Stress-Strain: Typically used up to the yield point or in elastic deformation. Beyond the yield point, the curve does not accurately represent the material's behavior due to necking or changes in cross-sectional area.
True Stress-Strain: Continues to represent material behavior accurately even after necking starts. This curve generally rises continuously, showing work hardening, until fracture.
2. Application:
Engineering stress-strain is simpler to measure and commonly used for design purposes where elastic behavior is predominant or for materials that do not neck significantly before failure.
True stress-strain is more useful for understanding the material's behavior at large deformations and for simulations or analyses where post-yield behavior is critical.
3. Graphical Representation:
In a true stress-strain curve, the stress increases even after the maximum engineering stress (ultimate tensile strength) due to the decrease in the cross-sectional area. This contrasts with the engineering curve where stress decreases post-ultimate strength due to necking.
4. Plasticity and Fracture:
True stress-strain can provide insights into plastic instability and the onset of necking, which are not as visible in engineering terms.
20/09/2024
Why is electrical continuity between fl**ges important in industrial setups, and what role does this bonding wire play in ensuring safety and system efficiency?
Electrical continuity between fl**ges is established to ensure that any potential difference or static charge between the fl**ges is neutralized, preventing arcing or sparking that could lead to safety hazards, especially in environments with flammable or explosive materials. This bonding method is essential in industrial piping systems to ground the fl**ges and maintain a uniform electrical potential, ensuring safe operation. It also helps to protect the system from corrosion caused by electrical discharges.
20/08/2024
𝐎𝐭𝐡𝐞𝐫 𝐒𝐭𝐚𝐢𝐧𝐥𝐞𝐬𝐬 𝐚𝐧𝐝 𝐇𝐞𝐚𝐭 𝐑𝐞𝐬𝐢𝐬𝐭𝐢𝐧𝐠 𝐒𝐭𝐞𝐞𝐥𝐬 𝐆𝐫𝐚𝐝𝐞𝐬 𝐂𝐨𝐦𝐩𝐨𝐬𝐢𝐭𝐢𝐨𝐧 𝐚𝐧𝐝 𝐀𝐩𝐩𝐥𝐢𝐜𝐚𝐭𝐢𝐨𝐧𝐬:
(𝑭𝒆𝒓𝒓𝒊𝒕𝒊𝒄, 𝑫𝒖𝒑𝒍𝒆𝒙, 𝑴𝒂𝒓𝒕𝒆𝒏𝒔𝒊𝒕𝒊𝒄, 𝒂𝒏𝒅 𝑷𝒓𝒆𝒄𝒊𝒑𝒊𝒕𝒂𝒕𝒊𝒐𝒏 𝑯𝒂𝒓𝒅𝒆𝒏𝒊𝒏𝒈 𝑺𝒕𝒂𝒊𝒏𝒍𝒆𝒔𝒔 𝑺𝒕𝒆𝒆𝒍𝒔)
14/07/2024
Types of Reduction Gear :
Reduction gear is an arrangement through which speed can be lowered (minimized) as per the requirement of slower output speed (with same or more required torque). Reduction gear mainly consist of set of gears which is in connection with wheel & their parts. The incoming high speed motion is transmitted through the set of rotating gears. (While in this case motion or torque has been changed). Number of gear to be used in the reduction gear is based on the output speed requirement as per the application. Reduction gear assembly also known as reduction gearbox.
Reduction gear is also used when reduction of high speed steam turbine motion into low RPM range (To be decided by propeller).
Mounting Option of Reduction Gears
Base mounted
Shaft mounted
Gearmotor
1. Base mounted :- Base mounted reducer gear which have feet for bolting (platform for stability) are the most common types.
2. Shaft mounted :- Shaft mounted reducer gear which having hollow output shaft that slip over the driven shaft.
3. Gearmotor :- A gearmotor combines an enclosed gearset along with a motor. A motorized reducer resembles a gearmotor except that is driven separate by NEMA C FACE motor.
Types of Reduction Gear ( Types of Gear )
There are mainly two types of reduction gear followed by:
Single reduction gear
Double reduction gear
1. Single Reduction Gear: ( Types of Gear )
Single reduction gear having arrangement that consist of one pair of gears. Reduction gearbox consist of different ports for propeller & engine shaft respectively to take entry inside of gear assembly. Assembly is also equipped with small gear known as pinion which is driven by incoming shaft of the engine while pinion is used to drive the large gear that is place on the propeller shaft. The speed is to be adjusted by maintaining the ratio of speed reduction to the diameter of pinion & gear proportional. A single gear assembly having a gear the double size of pinion.
2. Double Reduction Gear: ( Types of Gear )
Double reduction gear is used in application that involving high speed specific needs. In this double reduction gear arrangement pinion is directly connected to input shaft (combines with flexible coupling connection). Intermediate gear is connected to first reduction gear. This first reduction gear is connected to pinion which is operating at low speed with help of another shaft. This pinion is connected to reduction gear that is mounted on the propeller/ shaft. This arrangement fascinates that gives speed reduction up to 20:1 .
Selection of Reduction Gears
Reduction gear comes in two class or configuration with different types while these classes are right angle class or parallel shaft type.
Right Angle Class
They are included with worm types equipped with bevel (straight or helical).and for parallel class of gear reducer having configuration of parallel shaft that include spur (internal & external), helical planetary or harmonic gears. It is also found possible in such a way that reduction gear composed of multi stages which occupies or involve one or more types of gear reducer.
Selection of gear reducer between these two classes based on to the space restriction of the application. Worm gear with speed reduction ratio of 20:1 or greater than this are self locking that can be desirable in application basic requirement is that load is on even after turned off the motor while worms gear are less efficient than the other types of gears which requires the large motor to achieve the same output torque.
08/07/2024
𝐇𝐨𝐭 𝐁𝐨𝐥𝐭𝐢𝐧𝐠:
The sequential removal and replacement of bolts on fl**ged joints while the unit is under reduced operating pressure. The procedure generally consists of removing one bolt at a time in a fl**ge, re-lubricating it, reinstalling it (or a new bolt), and retightening it to a specified torque. Hot bolting can be performed while the unit is online or once the unit is depressurized. If performed while the unit is online, consideration of the risk of leakage includes the number of bolts in the fl**ge and the hazard associated with the contained process fluid. Hot bolting is used either to replace corroded or defective bolts or to proactively increase the gasket stress to prevent leakage (in high-temperature or cyclic services) or to reseal a small stable leak.
𝑵𝑶𝑻𝑬: Hot bolting while the unit is online to increase gasket stress or seal a small stable leak is not recommended or required if turn-of-nut tightening can be used. An engineering and risk analysis of the hot-bolting operation should be carried out to establish that the operation can be performed safely. 𝑹𝒆𝒇𝒆𝒓 𝒕𝒐 𝑨𝑺𝑴𝑬 𝑷𝑪𝑪-2 for further information on joint-tightening activities once the unit is fully operational.
07/05/2024
𝐇𝐲𝐝𝐫𝐨𝐠𝐞𝐧 𝐒𝐨𝐮𝐫𝐜𝐞𝐬 𝐢𝐧 𝐒𝐡𝐢𝐞𝐥𝐝𝐞𝐝 𝐌𝐞𝐭𝐚𝐥 𝐀𝐫𝐜 𝐖𝐞𝐥𝐝𝐢𝐧𝐠 (𝐒𝐌𝐀𝐖)
Hydrogen can find its way into the welding process through various sources:
► The coatings on SMAW electrodes can absorb moisture from the atmosphere, which dissociates during welding, releasing hydrogen.
► Any hydrocarbons or oils present on the base metal surface or within the electrode coating can contribute to hydrogen generation.
► High humidity in the welding environment can introduce moisture, leading to hydrogen formation.
𝗗𝗲𝘁𝗿𝗶𝗺𝗲𝗻𝘁𝗮𝗹 𝗘𝗳𝗳𝗲𝗰𝘁𝘀 𝗼𝗳 𝗛𝘆𝗱𝗿𝗼𝗴𝗲𝗻:
➊ 𝙃𝙮𝙙𝙧𝙤𝙜𝙚𝙣 𝙀𝙢𝙗𝙧𝙞𝙩𝙩𝙡𝙚𝙢𝙚𝙣𝙩: Hydrogen atoms can diffuse into the hot, solidifying weld metal and heat-affected zone (HAZ), causing a loss of ductility and toughness, potentially leading to delayed cracking or fisheye formation.
➋ 𝙋𝙤𝙧𝙤𝙨𝙞𝙩𝙮: Excessive hydrogen can result in porous welds, with small, dispersed bubbles or cavities within the weld.
➌ 𝙐𝙣𝙙𝙚𝙧-𝙗𝙚𝙖𝙙 𝘾𝙧𝙖𝙘𝙠𝙞𝙣𝙜: Hydrogen accumulation in the root area of the weld can cause cracking along the weld root, known as under-bead cracking.
𝗔𝘃𝗼𝗶𝗱𝗶𝗻𝗴 𝗛𝘆𝗱𝗿𝗼𝗴𝗲𝗻 𝗶𝗻 𝗦𝗠𝗔𝗪:
✧ 𝙋𝙧𝙤𝙥𝙚𝙧 𝙀𝙡𝙚𝙘𝙩𝙧𝙤𝙙𝙚 𝙃𝙖𝙣𝙙𝙡𝙞𝙣𝙜 𝙖𝙣𝙙 𝙎𝙩𝙤𝙧𝙖𝙜𝙚:
Store electrodes in dry conditions and follow the manufacturer's recommendations for baking or drying before use.
✧ 𝙋𝙧𝙚𝙝𝙚𝙖𝙩𝙞𝙣𝙜:
Preheating the base metal before welding helps reduce the cooling rate and promote hydrogen diffusion out of the weld.
✧ 𝙋𝙤𝙨𝙩-𝙒𝙚𝙡𝙙 𝙃𝙚𝙖𝙩 𝙏𝙧𝙚𝙖𝙩𝙢𝙚𝙣𝙩:
Stress-relieving or other post-weld heat treatments can help diffuse hydrogen from the weld and HAZ, reducing cracking risks.
✧ 𝙇𝙤𝙬-𝙃𝙮𝙙𝙧𝙤𝙜𝙚𝙣 𝙀𝙡𝙚𝙘𝙩𝙧𝙤𝙙𝙚𝙨:
Use electrodes specifically designed with low-hydrogen coatings to significantly reduce hydrogen introduction.
✧ 𝙎𝙪𝙧𝙛𝙖𝙘𝙚 𝙋𝙧𝙚𝙥𝙖𝙧𝙖𝙩𝙞𝙤𝙣:
Thorough cleaning of the base metal surface to remove oils, greases or contaminants that can contribute to hydrogen generation.
✧ 𝘾𝙤𝙣𝙩𝙧𝙤𝙡𝙡𝙞𝙣𝙜 𝘼𝙩𝙢𝙤𝙨𝙥𝙝𝙚𝙧𝙞𝙘 𝘾𝙤𝙣𝙙𝙞𝙩𝙞𝙤𝙣𝙨:
Maintain a dry welding environment by using dehumidifiers or shielding gas systems to minimize moisture and hydrogen introduction.
23/04/2024
Breaking News!!! Just got discovered the best sensor that exists in the world.
21/04/2024
𝗟𝗣 𝗧𝘂𝗿𝗯𝗶𝗻𝗲 𝗜𝗻𝘁𝗲𝗴𝗿𝗶𝘁𝘆 𝗨𝗻𝗱𝗲𝗿 𝗦𝗰𝗿𝘂𝘁𝗶𝗻𝘆: 𝗖𝗼𝗿𝗿𝗼𝘀𝗶𝗼𝗻 𝗮𝗻𝗱 𝗗𝗲𝘀𝗶𝗴𝗻 𝗔𝗻𝗮𝗹𝘆𝘀𝗶𝘀
Steam turbines boast a lifespan exceeding 30 years, with overhauls typically every 10 years. However, approximately 5 percent encounter corrosion and deposition issues.
𝗥𝗼𝗼𝘁 𝗖𝗮𝘂𝘀𝗲𝘀 𝗼𝗳 𝗙𝗮𝗶𝗹𝘂𝗿𝗲𝘀:
Failures in blades and discs stem from various factors, including design flaws with high stresses, poor steam chemistry, and the use of high-strength materials.
𝗖𝗼𝗺𝗺𝗼𝗻 𝗦𝘁𝗲𝗮𝗺 𝗧𝘂𝗿𝗯𝗶𝗻𝗲 𝗣𝗿𝗼𝗯𝗹𝗲𝗺𝘀:
𝘾𝙤𝙧𝙧𝙤𝙨𝙞𝙤𝙣 𝙖𝙣𝙙 𝘿𝙚𝙥𝙤𝙨𝙞𝙩𝙞𝙤𝙣: Leading to LP blade and disc rim failures.
𝙇𝙤𝙬 𝘾𝙮𝙘𝙡𝙚 𝙏𝙝𝙚𝙧𝙢𝙖𝙡 𝙁𝙖𝙩𝙞𝙜𝙪𝙚: Resulting from repetitive heating and cooling.
𝙇𝙤𝙨𝙨 𝙤𝙛 𝙈𝙒/𝙃𝙋 𝙖𝙣𝙙 𝙀𝙛𝙛𝙞𝙘𝙞𝙚𝙣𝙘𝙮: Due to deposits impacting performance.
𝙒𝙖𝙩𝙚𝙧 𝘿𝙧𝙤𝙥𝙡𝙚𝙩 𝙀𝙧𝙤𝙨𝙞𝙤𝙣: Damaging turbine components over time.
𝙁𝙡𝙤𝙬 𝘼𝙘𝙘𝙚𝙡𝙚𝙧𝙖𝙩𝙚𝙙 𝘾𝙤𝙧𝙧𝙤𝙨𝙞𝙤𝙣: Influencing material degradation.
𝙎𝙤𝙡𝙞𝙙 𝙋𝙖𝙧𝙩𝙞𝙘𝙡𝙚 𝙀𝙧𝙤𝙨𝙞𝙤𝙣: Caused by magnetite particles from superheaters.
𝙏𝙪𝙧𝙗𝙞𝙣𝙚 𝘿𝙚𝙨𝙩𝙧𝙪𝙘𝙩𝙞𝙫𝙚 𝙊𝙫𝙚𝙧𝙨𝙥𝙚𝙚𝙙: Caused by control valve issues due to deposits.
𝙒𝙖𝙩𝙚𝙧 𝙄𝙣𝙙𝙪𝙘𝙩𝙞𝙤𝙣-𝙒𝙖𝙩𝙚𝙧 𝙃𝙖𝙢𝙢𝙚𝙧: Posing risks of sudden pressure spikes.
𝗣𝗿𝗲𝘃𝗲𝗻𝘁𝗮𝘁𝗶𝘃𝗲 𝗠𝗲𝗮𝘀𝘂𝗿𝗲𝘀:
All issues are well-understood, detectable, and preventable through various methods, including monitoring, inspection, and defect evaluation. These include design reviews, NDT, vibration monitoring, and chemical analysis.
𝗜𝗻𝗳𝗹𝘂𝗲𝗻𝗰𝗲 𝗼𝗳 𝗦𝘁𝗲𝗮𝗺 𝗖𝘆𝗰𝗹𝗲 𝗗𝗲𝘀𝗶𝗴𝗻:
Steam cycle design and operation play a crucial role in turbine problems, affecting stresses, thermal conditions, and water/steam purity, thus necessitating diligent monitoring and maintenance.
𝙁𝙞𝙫𝙚 𝙖𝙧𝙚𝙖𝙨 𝙤𝙛 𝙙𝙚𝙨𝙞𝙜𝙣 𝙖𝙛𝙛𝙚𝙘𝙩 𝙩𝙪𝙧𝙗𝙞𝙣𝙚 𝙘𝙤𝙧𝙧𝙤𝙨𝙞𝙤𝙣:
𝗠𝗲𝗰𝗵𝗮𝗻𝗶𝗰𝗮𝗹 𝗗𝗲𝘀𝗶𝗴𝗻: Considerations include stresses, vibration, stress concentrations, and frictional damping.
𝗣𝗵𝘆𝘀𝗶𝗰𝗮𝗹 𝗦𝗵𝗮𝗽𝗲: Aspects such as stress concentration, crevices, and surface finish impact corrosion.
𝗠𝗮𝘁𝗲𝗿𝗶𝗮𝗹 𝗦𝗲𝗹𝗲𝗰𝘁𝗶𝗼𝗻: Factors like maximum yield strength, corrosion properties, and material damping are critical.
𝗙𝗹𝗼𝘄 𝗮𝗻𝗱 𝗧𝗵𝗲𝗿𝗺𝗼𝗱𝘆𝗻𝗮𝗺𝗶𝗰𝘀: Flow excitation, condensation, and velocity affect corrosion dynamics.
𝗛𝗲𝗮𝘁 𝗧𝗿𝗮𝗻𝘀𝗳𝗲𝗿: Surface temperature, evaporation, and stress expansion influence corrosion rates.
03/04/2024
FORGING - Mechanism and Types
Metal forging is a manufacturing process in which metal is shaped and formed through the application of localized compressive forces. The process typically involves heating the metal to a high temperature, making it more malleable, and then using a tool or die to apply force to deform it into the desired shape.
Key characteristics and steps of metal forging include:
- Heating: The metal is heated to a temperature where it becomes more pliable and can be easily shaped. The exact forging temperature varies depending on the type of metal being used.
- Forging: There are various methods of forging, including:
➡️ Hammer Forging: In this method, a power hammer or a mechanical hammer is used to repeatedly strike the heated metal to shape it.
➡️Press Forging: Hydraulic or mechanical presses are employed to apply a steady, controlled force to the metal, shaping it into the desired form.
➡️Roll Forging: The metal is passed between two rollers that exert pressure on it, changing its shape.
➡️Die Design: Dies or molds are used to define the shape and dimensions of the final forged product. These molds can be simple or highly complex, depending on the part being produced.
- Cooling: After the forging process, the metal is often quenched or cooled to set its shape and strengthen its structure. This cooling process can be done using various methods, including air cooling, water quenching, or oil quenching.
- Trimming and Finishing: The forged part may require additional trimming, machining, or finishing operations to meet precise specifications and surface quality standards.
20/03/2024
Tensile Fracture:
Ductile vs. Brittle Behavior in Materials 🛠️
🛠️ :
▪️ Ductile materials, like many metals, have the ability to stretch and deform significantly before breaking.
▪️ When subjected to tension, ductile materials undergo plastic deformation, meaning their atoms rearrange to absorb energy and allow elongation.
▪️ The fracture process in ductile materials involves necking, a localized thinning that occurs just before the final break. This can provide warning signs and time for corrective measures.
🔧 :
▪️ Brittle materials, such as ceramics and glass, lack significant plastic deformation capabilities.
▪️ When exposed to tension, they break suddenly without much deformation. This happens due to the limited atomic movement and weak bonding within the material.
▪️ Brittle fractures result in clean, straight breaks without much warning, resembling the snapping of a twig.
🌐 Practical Implications and Considerations:
★ Material Selection: Engineers consider these behaviors when choosing materials for specific applications. Ductile materials are often preferred for structures that require flexibility and gradual failure, while brittle materials find use in applications demanding minimal deformation.
★ Design and Safety: Understanding the fracture behavior aids in designing structures that can withstand various stress conditions. Bridges, airplanes, and critical equipment are designed with these properties in mind.
★ Failure Analysis: Analyzing fractures can provide valuable insights into the causes of failures, helping industries enhance their products and processes.