The X Dimension - Mandatory or Not? The back face ID (“X”) dimension on 6B flanges carries a note: Reference dimension. It does not meet the usual definition of reference dimensions, which are dimensions that can be calculated from other dimensions of the part. In the source document for the design of Type 6B flanges, ASME Specification B16.5, the X dimension is clearly mandatory. The author believes it should be a mandatory dimension.

Issue 1: Flange neck diameter for 6B flanges (2000 – 5000 psi) is not specified. (shown as a reference dimension but not defined elsewhere or by other dimensions) Proposed change: Revise Tables 49, 50, 51, B49, B50, B51 to remove footnote ‘a’ (“ a Reference dimension”) Proposed action: Ballot and publish as errata. SC6 Resource Group on Trees and Wellhead

Issue 2: 6A clause b) requires hydrostatic testing of electric actuators. Proposed change: Change title of : from “b) pneumatic, hydraulic or electric actuators” to “b) pneumatic or hydraulic actuators.” (Note: Would then be consistent with a) ) Proposed action: Publish as erratum. SC6 Resource Group on Trees and Wellhead