Pressure Vessels – The ASME Code Simplified

Pressure Vessels – The ASME Code Simplified

History of the ASME Code
On March 20, 1905, a disastrous boiler explosion occurred in a shoe factory
in Brockton, Massachusetts, killing 58 persons, injuring 117 others,
and causing a quarter of a million dollars in property damage. For years
prior to 1905, boiler explosions had been regarded as either an inevitable
evil or “an act of God” (see Figs. 1.1 and 1.2). But this catastrophic accident
had the effect of making the people of Massachusetts see the necessity
and desirability of legislating rules and regulations for the
construction of steam boilers in order to secure their maximum safety.
After much debate and discussion, the state enacted the first legal code
of rules for the construction of steam boilers in 1907. In 1908, the state
of Ohio passed similar legislation, the Ohio Board of Boiler Rules adopting,
with a few changes, the rules of the Massachusetts Board.
Therefore, other states and cities in which explosions had taken
place began to realize that accidents could be prevented by the proper
design, construction, and inspection of boilers and pressure vessels and
began to formulate rules and regulations for this purpose. As regulations
differed from state to state and often conflicted with one another,
manufacturers began to find it difficult to construct vessels for use in
one state that would be accepted in another. Because of this lack of uniformity,
both manufacturers and users made an appeal in 1911 to the
Council of the American Society of Mechanical Engineers to correct the
situation. The Council answered the appeal by appointing a committee
“to formulate standard specifications for the construction of steam boilers
and other pressure vessels and for their care in service.”

Finite Element Simulation of Fillet Welds




In this study, residual stress results for different fillet geometries are compared

with previous welding simulation results obtained for a simple “straight” fillet weld in a

longitudinal stiffener [12] (see Fig. 1a). In [12], an axisymmetric model was developed

to approximate the welding stresses in a circular arc around the end of the longitudinal

stiffener. As shown in Fig. 1b, a cross-section of the end of the longitudinal stiffener

provides the geometric dimensions for a circular swept arc that can reasonably represent

the 3-D state of stress at the far ends of the welded joint. The results in [12] illustrated

how the boundary conditions (clamps conditions) and metallurgical phase changes could

the influence residual stresses near the fillet weld

Description of the Welding Simulation Suite

Description of the Welding Simulation Suite



If You …
Want to virtually manufacture each welded design before it is fabricated or repaired.
Work with sheet metal, heavy plates, or both.
Work with structural steel, complex materials, or dissimilar metals in the aerospace, energy, nuclear or chemical
Require that your welded designs meet tolerance requirements, at minimum cost and within minimum time –
without the necessity of incorporating all the details of complex physics.
Need to optimize the distortion of a welding assembly, taking into account all process details.
Need to ensure that the microstructure after welding meets your requirements.
Need to determine residual stresses as a basis for a high cycle low amplitude fatigue analysis, and to discover
problem zones in the design.
Want to understand the stress and fracture mechanics of the cladding, the heat treatment, and the welding process
of large dissimilar metal welded assemblies caused by the fabrication or repair process.

چرخ دنده ها

چرخ دنده ها


چرخدنده وسیله ای برای انتقال مکانیکی توان یا حرکت بین محورهای متوازی، متقاطع یا متنافر است. با اینکه معمولا چرخ دنده ها بدلیل اینکه در بیشتر موارد بمنظور رعایت ایمنی درون پوششهای فیزیکی قرار میگیرند، از نظر پنهان میباشند، مهمترین عنصر مکانیکی تمدن بشری بوده و حتی اهمیتشان از چرخ هم بیشتر است، زیرا بیشتر چرخها بدون نیروی دریافتی از چرخ دنده ها قابل حرکت نیستند.

جوش و بازرسی جوش و متالوژی

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جوش و بازرسی جوش و متالورژی


سوپر آلياژها داراي خواص متنوعي بوده و به منظور برآورده كردن نيازمنديهاي گسترده و متنوع مصرف كنندگان، بوجود آمده اند يك سوپر آلياژ ، آلياژي است كه براي كار در دماي بالا توسعه يافته، معمولاً زمينة آن روي عناصر گروه VII ست در جائي كه تنشهاي مكانيكي شديد حادث مي‌شوند و صافي و يكنواختي سطحي مورد نياز است. اين آلياژها معمولاً از فرمولهاي مختلفي كه از عناصر زير در آنها بهره برده‌اند تشكيل شده است. آهن، نيكل، كبالت و كروم همينطور مقدار بسيار كمي تنگستن موليبدن، تانتاليم، نيوبيوم، تيتانيم و مقاومت در برابر خوردگي كرم و سائيدگي مي‌باشد. انواع بسياري از آلياژها در دستة وسيعي از سوپر آلياژها قرار مي‌گيرند. اينها عبارتند از: آلياژهاي پاية اهن، تشكيل شده از كروم و نيكل، و تركيبي از مخلوط Fe – Ni – Cr – Co ، آلياژهاي با زمينة كبالت كه به وسيلة كاربيد تقويت شده‌اند .

Modelling Residual Stress and Phase

Modelling Residual Stress and Phase


Mathematical modelling of welding phenomena is very complex: involving melt pool

phenomena, solidification, weldability analysis, microstructure evolution in the heat

affected zone, welding heat-flow simulation, electrical-thermal-mechanical simulation etc.

Some interactions between these processes are included in Fig. 1. Each topic alone can be

intellectually challenging and too hard to be investigated by classical methods. With the

increasing power of modern computer systems, numerical modelling and especially finite

element analyses make it possible to produce excellent solutions to satisfy engineering