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Subject: 17D Blind Flanges Without raised faces


My company is assembling some 17D equipment for subsea use, and one of the lines has a studded tee serving as an elbow with a blind flange closing the run to provide a fluid cushion. I observed on the assembly drawings, that neither the studded tee or the connecting blind flange have a raised face, but my experience with 6A 6BX flanges suggests to me that at least one of the mating flange connectors must have a raised face.

Am I correct in my assessment?


You will find the following answer to your question contained within the information at .

CAUTION: API Spec 17D specifically states, “All Flanges used on Subsea completions equipment shall be of the ring joint type designed for face-to-face make-up. The connection make-up force and external loads shall react primarily on the raised face of the flange. Therefore, at least one of the Flanges in a connection shall have a raised face.” API Spec 17D specifies an optional raised face on 17D Type SS Blind Flanges. WOODCO USA recommends that API 17D SS Blind Flanges always have raised faces.

API Spec 17D makes no mention of Studded Flange connectors as specified in API Spec 6A, but does not prohibit them. The implication of acceptance of API Spec 6A connections, and the fact that API Spec 6A permits the omission of raised faces on studded face 6BX Flanges will surely result in operators attempting to install a 17D SS Blind Flange without a raised face onto an API 6A studded face connection, also without a raised face. Without using technical terms, any kind of damage to, or coating on, the face of either of the joining full face flange connectors with BX ring grooves will prevent the face to face contact intended and explained in API Spec 17D.


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