ASME B31.3 paragraph 335.1(c)

[anolan23]

335.1(c)refers to the design plane when talking about flange misalignment. What is exactly the definition of design plane? Is it the plane of the mating face?

 

[david339933]

Which year B31.3 are you using....There is no reference to design plane in the 2016 edition.

 

[XL83NL]

Neither in the 2018 edition.

 

[DekDee]

2008

(c) Flanged Joints. Before bolting up, flange faces shall
be aligned to the design plane within 1 mm in 200 mm
(1⁄16 in./ft) measured across any diameter; flange bolt
holes shall be aligned within 3 mm (1⁄8 in.) maximum
offset.

 

[AppletonBowen]

I have always thought about this in the sense of hanging a clock on a wall.
- 1:200mm is the parallelism of the clock (flange face) against the wall (stationary flange); hence, any diameter means applicable in any/every direction.
- 3mm maximum distance tolerance on 12 o'clock position (bolt holes).

I believe the clause was included to give baseline tolerances to help avoid induced stresses from bolting poorly aligned flanges together. I can't comment on why the clause may have been removed, however.