ASME STP/PT-004:2005 pdf free download

ASME STP/PT-004:2005 pdf free download.IMPREGNATED GRAPHITE FOR PRESSURE VESSELS.
4 DESIGN
4.1 Existing Codes for Graphite Pressure Vessels
Currently there are no rules in the ASME Boiler and Pressure Vessel Code for the design and construction of graphite pressure vessels. Most of the recently constructed graphite pressure vessels follow the design and construction practices of the German pressure vessel code AD Merkblatt N2 [8], as well as experience driven procedures. These include requirements for materials, testing of graphite materials, marking, certification of quality, allowable stresses, tolerances and surface finish, and design calculations (including factors of safety for design and for pressure tests). Annex 3 to AD Merkblatt includes requirements for tension testing of graphite materials and the details of the tension test specimen. However, the acceptance criteria for mechanical properties to be used in design in AD Merkblatt N2 is less restrictive than that proposed for Part UIG.
The Dutch Rules for pressure vessels include Specification 1) 1401/83-12, Graphite Block Heat Exchangers [9], and M 080783-12, Impregnated Graphite [101. and reference AD Merkhlatt N2 as part of the requirements for impregnated graphite.
4.2 Permissible Design Temperature
The German Technical Supervisory Hoard (Technische Uberwachungsverein, or TUV) permits a maximum design emperature of 200°C (392°F) for impregnated graphite vessels. AD Mcrkblatt N2 limits the minimum design temperature to -60°C (-76°F). The design temperature for impregnated graphite vessels to be designed and constructed to the proposed Part UIG is limited to the same ralueS
4.3 Properties for Design of Impregnated Graphite Vessels and Components
Pressure vessels and pressure components of impregnated graphite shall at least meet the requirements listed in Table 1.
4.5Buckling of Cylindrical Shells
According to the German Pressure Vessel Code AD-Merkblatt N2 [8], paragraph 8.4, clastic bucklingfrom external pressure need not be considered in the design. Because of low design stresses(compared to those for ferrous and nonferrous materials) and low D’t ratios，elastic buckling ofgraphite shells is not of concern.However, calculations need to be performed for plastic deformation,in which case the tensile strength value K used in the design is increased by a factor of 2.5 inEquation 4, which takes into account the higher compressive strength of impervious graphitecompared to the tensile strength. In design of tubes under external pressure, the tensile strength valueK may be increased by a factor of 2.
The allowable external pressure for plastic deformation in AD-Merkblatt B6 is given by the following equation.