API 6A Seal Ring Groove Gages (BX & R/RX)
A ring groove is basically a closely dimensioned groove cut into the face of a pipe flange. Together with a gasket, a groove helps create a seal between parts, so it is important that a groove meets designated specifications.  

A ring groove is basically a closely dimensioned groove cut into the face of a pipe flange. Together with a gasket, a groove helps create a seal between parts, so it is important that a groove meets designated specifications.  

API 6A ring grooves are divided into three ring types, BX, R, and RX. Each type has different configurations and is designated by the type and a number, i.e. BX 150, R 41, etc.

API mandates the inspection of ring grooves. The necessary dimensions of a groove are clearly specified in API 6A. To pass API requirements, these dimensions must be met. For BX Grooves, the groove’s major diameter and width are specified. For R and RX Grooves, API specifies the groove’s pitch diameter and width.

	Groove	Groove Diameter or Grove Width	Range^	Contact Points Included*	Indicator Travel	Indicator Resolution	Description	Model
	BX, R, RX	Diameter	2.6” - 13” (66 mm - 330.2 mm)	Customer Choice	-	-	Ball mic gage includes customer specified ball contact points (no indicator)	BX-900
	BX, R, RX	Diameter	2.6” - 13” (66 mm - 330.2 mm)	T188	.250”	.0005”	6A groove diameter gage includes T188 contact points*	BX-1000
	BX, R, RX	Diameter	2.6” - 13” (66 mm - 330.2 mm)	T188	.500"	.0001”	6A groove diameter gage with .0001” resolution includes T188 contact points*	BX-1000-1
	BX, R, RX	Width	.375” -1.5” (9.5 mm - 38.1 mm)	T072	.250”	.0005”	6A groove width gage includes T072 contact points*	BXG-1000
	BX, R, RX	Width	.375” -1.5” (9.5 mm - 38.1 mm)	T072	.500"	.0001”	6A groove width gage with .0001” resolution indicator, includes T072 contact points*	BXG-1000-1
	BX, R, RX	Width	.375” -1.5” (9.5 mm - 38.1 mm)	T072	5 mm	.01 mm	6A groove width gage with metric indicator, includes T072 contact points*	BXG-1000-M
	BX, R, RX or Custom	Width	.312” - 2.375” (8 mm - 60.3 mm)	T072	.250”	.0005”	Groove width gage includes T072 contact points*	BXG-1002
	BX, R, RX or Custom	Width	.312” - 2.375” (8 mm - 60.3 mm)	T072	.500”	.0001”	Groove width gage with .0001” resolution indicator, includes T072 contact points*	BXG-1002-1
	BX, R, RX or Custom	Width	.312” - 2.375” (8 mm - 60.3 mm)	T072	5 mm	.01 mm	Groove width gage with metric indicator, includes T072 contact points*	BXG-1002- M
	-	-	-	-	.500”	.001”	BX/BXG ball height setting gage, ½” X ½” U-notch base	PD-BX