"nominal" means of existing, in name, not in fact
"nominal diameter" is called NPS in ASME & DN in DIN,
NPS4 is comparable to DN100

NPS5 / DN125 is not a common size

ASME: NPS14 and above, the "nominal diameter" is in fact the OD
DIN: no such thing !

ASME: different wall thickness is refered as SCHEDULE @ SCH
DIN: different wall thickness is refered as OTHER WALL THICKNESS

the critical dimension of pipe flange is
1) number of bolt-hole
2) diameter of bolt-hole
3) pole center diameter (PCD)

Class150 means nominal pressure of 150psi, PN10 means nominal pressure of 10bar
it is wrong to interpret any Class150 can withstand 150psi at all condition
it is depending on these 3 factors:
1) material
2) pressure
3) temperature

technical evaluation / inspection for a valve:
1) flange-to-flange distance
2) nominal pressure
3) nominal diameter

important terms:
1) weld-neck vs slip-on
2) welded vs seamless
3) raised face serrated face (RFSF)


ASME B16.5 = pipe flanges & flanged fittings from NPS 1/2 TO 24
ASME B16.9 = factory-nade wrought steel butt welding fittings NPS 1/2 to 48
ASME B16.10 = face-to-face & end-to-end dimension of valves
ASME B16.47 = large diameter steel flanges from NPS 26 to 60
ASME B31.1 = power piping
ASME B31.3 = process piping
ASME B36.10 = welded & seamless wrought steel pipe
ASME B36.19 = stainless steel pipe


DIN 2632 = weld-neck pipe flanges for PN10
DIN 2633 = weld-neck pipe flanges for PN16

under-construction !!!

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