Pressure vessels high-alloy steels

ASTM A 517, Specification for Pressure Vessel Plates, Alloy Steel, High-Strength, Quenched and Tempered... 

Pressure vessels are constructed from plain carbon steels, low and high alloy steels, other alloys, clad plate, and reinforced plastics. 

The central part of the plant is the reactor pressure vessel housing the reactor core with its components as well as the water-steam separators and the steam dryers (see Fig. 2.2.). The dimensions of this component (inner diameter 6.62 m, height 22.35 m, total weight 785 Mg) exceed the dimensions of a PWR reactor pressure vessel considerably. The reactor pressure vessel is made from the high-alloy steel 22NiMoCr37 with an austenitic weld overlay on the inner surface. In its cylindrical section, the wall thickness of the vessel is 16.3 cm plus a weld overlay of 0.8 cm. 

The fifth component is the stmcture, a material selected for weak absorption for neutrons, and having adequate strength and resistance to corrosion. In thermal reactors, uranium oxide pellets are held and supported by metal tubes, called the cladding. The cladding is composed of zirconium, in the form of an alloy called Zircaloy. Some early reactors used aluminum fast reactors use stainless steel. Additional hardware is required to hold the bundles of fuel rods within a fuel assembly and to support the assembhes that are inserted and removed from the reactor core. Stainless steel is commonly used for such hardware. If the reactor is operated at high temperature and pressure, a thick-walled steel reactor vessel is needed. 

Vessels for high-temperature serviee may be beyond the temperature hmits of the stress tables in the ASME Codes. Sec tion TII, Division 1, makes provision for construction of pressure vessels up to 650°C (1200°F) for carbon and low-alloy steel and up to 815°C (1500°F) for stainless steels (300 series). If a vessel is required for temperatures above these values and above 103 kPa (15 Ibf/in"), it would be necessaiy, in a code state, to get permission from the state authorities to build it as a special project. Above 815°C (1500°F), even the 300 series stainless steels are weak, and creep rates increase rapidly. If the metal which resists the pressure operates at these temperatures, the vessel pressure and size will be limited. The vessel must also be expendable because its life will be short. Long exposure to high temperature may cause the metal to deteriorate and become brittle. Sometimes, however, economics favor this type of operation. 

Tube material includes any that can be formed into a coil, but usually copper, copper alloys, and stainless steel are most common. The casing or shell material can be cast iron, cast steel, cast bronze, fabri-catea steel, stainless, and other high-alloy materials. Units are available with pressure vessel code conformance. 

The submitters employed a nickel autoclave and noted that product from Step D may contain a small amount of hydrogen chloride or chlorinated material than can adversely affect a stainless steel pressure vessel. Hastelloy C is a high-nickel alloy. 

Low-alloy steel (-r = 0.8 Mn) Fe + 0.2 C 0.8 Mn High-stress uses pressure vessels, aircraft ports. 

Pittman (1972) performed five experiments with titanium-alloy pressure vessels which were pressurized with nitrogen until they burst. Two cylindrical tanks burst at approximately 4 MPa, and three spherical tanks burst at approximately 55 MPa. The volume of the tanks ranged from 0.0067 m to 0.170 m. A few years later, Pittman (1976) reported on seven experiments with 0.028-m steel spheres that were pressurized to extremely high pressures with argon until they burst. Nominal burst pressures ranged from 100 MPa to 345 MPa. Experiments were performed just above ground surface. 

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