Piping Engineering / Design Blog.


Pipe Flanges – Do’s and Don’ts

Posted by Antony Thomas at Monday, January 27, 2014

Pipe Flanges – DO’s and DON’Ts


a) Always visually inspect the surface finish of the flange for injurious defects. It should be clean, degreased and free of any defects, nicks or burrs. The permissible imperfections in flange surface finish specified in ASME B16.5, Table 3 are not allowed for critical applications. Raised Face and Flat Face flanges should also be checked for flatness with a straight edge.
b) All rust and burrs must be removed, small scratches should be removed by polishing, other defects may mean component replacement.
c) Check the phonographic or concentric groove on the face of Raised Face and Flat Face flanges. Any radial defects for example will be virtually impossible to seal against.
d) RTJ grooves must be kept scrupulously clean, corrosion free and undamaged.


a) When cleaning a flange face, never use a tool which may damage the surface finish. A soft wire brush is recommended.
b) Do not use unnecessary force; say by tirforing or pulling, to bring flanges which are clearly misaligned together. This may overstress adjacent pipework and will make sealing of the flanged joint difficult and unreliable. Instead, report the situation.

c) Do not mate flanges manufactured to different unless specified in an approved design.


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