ASME code for unfired pressure vessels

ASME Code for Unfired Pressure Vessels, Section VIII, Division I... 

Figure 18.15. References to items covered in the ASME Code for Unfired Pressure Vessels, Section VIII Division 1 (Chuse and Eber, 1984).

Storage tanks should be designed in accordance with the ASME code for unfired pressure vessels. All-welded construction is recommended. Ethylene oxide storage tanks should be electrically grounded, isolated from potential fire hazards, and equipped with pressure relief devices. New equipment should be cleaned of iron oxide and immediately puiged with inert gas. 

These supports will not make a rectangular or square vessel suitable for pressure or vacuum service. If such a vessel is to receive a masonry lining, it must be designed as a cylinder with dished or hemispherical heads, both top and bottom or as a sphere. (Reference 8, p 80). Such vessel must also be designed in accordance with the ASME Code For Unfired Pressure Vessels, Section VIII. 

We will now consider the special problems in tall tower design which are not described in the ASME Code for Unfired Pressure Vessels. As discussed previously, circumferential stresses control the design of cylindrical vessels if external loads are of small magnitude. In tall vertical vessels, four major factors (wind load, seismic loads, dead weight and vibration) may contribute to axial stresses — in addition to axial stress produced by the operating pressure or vacuum of the vessel. 

The comparisons shown on Charts 1 and 2 are based on the 1956 Revision of Section 8 of the ASME Code for unfired pressure vessels. The clad-steel stress values used are based on the use of the full thickness of the composite plate as permitted by this Code. A factor of safety of 4 is used in all calculations. 

Construction In accordance with ASME Code for Unfired Pressure Vessels all-welded with flanged and dished heads shell thickness in., head thickness Ke in. 

Example of Analysis of Reinforcing Area for Opening IN Shell. The following example is quoted from the 1956 edition of the ASME code for unfired pressure vessels (11). This example illustrates the recommended procedure for calculating the required reinforcement for an opening in a shell. 

Note that for fired boilers, where the safety valve installation must comply with the ASME Code for Power Boilers rather than the code for Unfired Pressure Vessels, the allowable accumulation is only 6% instead of 10%. Reference also should be made to the Kj and A definitions, above. 

Standard calculation forms can save considerable time in pressure vessel design. These forms also systematize the mechanical design procedure to insure that nothing is omitted. Most engineering contractors have developed their own vessel calculation forms. Basically, all are alike in that they correlate, in easy-to-use fashion, the design rules set forth in Section VIII of the ASME Boiler and Pressure Vessel Code for Unfired Pressure Vessels. They also include design considerations not covered by the code, such as wind loading for tall vessels. (Text continues on p. 139.)... 

Pressure- Vessel Standards. Explosion-clad plates for pressure vessels are tested according to the appHcable ASME Boiler and Pressure Vessel Code Specifications. Unfired pressure vessels using clads are covered by ASTM A263, A264, and A265 these include tensile, bend, and shear tests (see Tanks AND pressure vessels). 

An abbreviated listing of the key rating provisions is given in paragraphs UG-125 through 135 of the ASME code, Section 8, Div. 1, for unfired pressure vessels [1]. 

Section I of the ASME code for fired boilers requires that the PSVs reach their full lift at a pressure not greater than 3% over their set point. Section VIII of the ASME code for unfired vessels does not provide a blowdown requirement, and the industrial practice is about 7%, which means that the normal operating pressure must be under 93% of set pressure. The position of the adjustable ring on the PSV nozzle controls the blowdown. This position establishes a secondary orifice area as the valve opens and closes. 

The first boiler code was published in 1915, the first Code (Section VIII) for Unfired Pressure Vessels in 1925. The allowable stresses were based on a factor of 5 on tensile strength. In 1934, the joint API-ASME code. Unfired Pressure Vessels for the Petroleum Industry, was published. It was based on a factor of 4 on tensile strength. In 1950, the ASME published a new edition of Section VIII which was also based on a factor of 4 on tensile strength. 

In 1931 a joint API-ASME Cumniilloe on Unfired Pressure Vessels was uppoiiitod to prepare a code for safe pnic-tice in the design, construction, inspection, and repair of unfired pressure vessels for petroleum liquids and gases. The API-ASME code was first published in September, 1934, and was revised in 1936, 1938, 1943, and 1951. The rly API-ASME code was considerably more lenient than section VIII of the then-existing ASME code. This resulted in the reduction of fabrication (x ts for vessels designed to tbe joint code. In recent y irs tbe ASME code has been broadened and improved so that it more completely covers the petroleum industry s pressure vessel needs and is in some respects more advanced (186). In May, 1956, the API-ASME code was officially discontinued, the discontinuation to beexime effective December 31, 1956, (186) and was supplanted by the 1956 edition of section VIII of the ASME Boiler and Pressure Ve el Code (11). 

ASME Boiler and Pressure Vessel Code. The ASME Boiler and Pressure Vessel Code is pubhshed in 11 sections. Section VIII, which is concerned with rules for the design of unfired pressure vessels, was first pubhshed in 1925 and since 1968 it has been issued in two parts. Division 1 (147) and Division 2 (148), the latter being known as the Alternative Rules. 

C = ASME Unfired Pressure Vessel Code constant for a vapor as described above, C is a function of the specific heat ratio, K. The equation given earlier for determining C is expressed in tabular form in Table 2. 

The American Society of Mechanical Engineers (ASME) Unfired Pressure Vessel Code is accepted by almost all states as a requirement by law and by most industrial insurance underwriters as a basic guide or requirement for fabrication of pressure vessel equipment, which includes some components of heat exchangers. 

Sometimes the design is governed by considerations that have little to do with heat transfer, such as the space available for the equipment or the pressure drop that can be tolerated in the fluid streams. Tubular exchangers are, in general, designed in accordance with various standards and codes, such as the Standards of the Tubular Exchanger Manufacturers Association (TEMA) and the ASME-API Unfired Pressure Vessel Code. ... 

The hazard of brittle-fracture is lessened as the average and local stress levels are lowered. Both the ASME Unfired Pressure Vessel Code (Par. UCS-66) and the Code for Pressure Piping (Par. 323.2.2) recognize this by allowing materials to be used below the transition temperature. Where the allowable stress is reduced to 40% of the normal allowable, the ASME Code permits such material to be used without limitation. The code for pressure piping sets an allowable stress of 15% of the maximum allowable without impact test. 

The American Society of Mechanical Engineers, ASME Boiler Pressure Vessel Code, Section VIII, Rules for Construction of Unfired Pressure Vessels, ASME, New York (1962). 

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