ASME PCC-1:2010 pdf free download

ASME PCC-1:2010 pdf free download.Guidelines for Pressure Boundary Bolted Flange Joint Assembly.
Dl FLANGE FACE FLATNESS TOLERANCES
Existing industry flatness tolerance limits’ do not include an assessment of the ability of the gasket to tolerate imperfections. The below tolerances are dependent on the type of gasket employed and are categorized based on the initial compression of the gasket to the final assembled load. Soft gaskets, such as spiral wound, PTFE, fiber, etc., have an assembly compression in excess of 1.0 mm (0.I in.). I-lard gaskets have less initial compression than this and, while this can help with improved assembly due to less bolt interaction, it generally means that they are more susceptible to flange flatness out-of-tolerance. It is not appropriate to classify by gasket type; for example, 1.5 mm (‘/, in.) thick I’TFE or fiber gaskets do not have sufficient compression to be classified as soft gaskets. It is suggested that load- compression test results for the gasket being used are obtained from the gasket manufacturer in order to determine which limits may be employed. It should be noted that the compression limit is measured perpendicular to the gasket surface and therefore gaskets such as the RTJ gasket type are to be regarded as hard gaskets.
It is acceptable to gauge mating flanges that have only one possible alignment configuration and determine that any waviness of the flange faces is complimentary, such that the seating surfaces follow the same pattern. This is found in multipass exchanger ints and is often caused by thermal distortion. In this case, it is conservative to calculate the overall gaps between the flanges at points around the circumference and utilize the single- flange tolerances as shown in Table D-1M and Table D-l to determine acceptability of the gap.
D-2 FI.ANGE FACE IMPERFECTION TOLERANCES
The tolerances shown in Table D-2M and Table D-2 are separated into two categories, depending on the gasket being employed in the joint. Soft-faced gaskets are gaskets that have sufficient soft filler (such as graphite, rubber, or l’TFE) that both the gasket and flange surface finish will be filled and additional filler exists on the gasket such that any small imperfections will also be filled as the gasket is compressed between the flanges. Care should he taken to ensure the correct tolerances are employed for the gasket being installed. It may not be acceptable to categorize by gasket type as extremely thin gaskets or gaskets without sufficient filler will not fill imperfections and therefore should he categorized as hard gaskets. Metal-laced gaskets, such as RTJ or double jacketed gaskets, are categorized as hard faced. It is important to note that the tolerances apply to the gasket seating surface (area where the gasket seats both initially and finally after assembly).