Page 192 - Well Control for Completions and Interventions

184 Well Control for Completions and Interventions

Table 4.5 American Petroleum Institute specification flange working pressure
Rated working pressure Flange size range

Type 6B (in.) Type 6BX (in.)
1
3
2000 2(1/16) 21/4 26/4 30
3
3
3000 2(1/16) 21/4 26/4 30
5
5000 2(1/16) 11 13/8 21/4
1
1
10,000 1(13/16) 21/4
15,000 1(13/16) 18/4
3
5
20,000 1(13/16) 13/8
Type 6B flanges have a maximum working pressure of 5000 psi, and
6BX flanges are rated to 20,000 psi (Table 4.5).
Some API 6B flanges are manufactured with a raised face. A raised
face on a 6B flange has no functional purpose, since the R or RX gasket
seal means there will always be a stand-off between to two flange faces.
At present, most manufacturers are making 6B flanges with a flat (some-
times called full) face, i.e., without a raised face.
For a 6BX flange to conform to the API 6A specification it must have
1
a raised face of at least /8 in. height, unless it is a studded face BX flange.
API Specification 6A gives the following reason for having a raised face,
“Depending on tolerances, the connection make-up bolting force may react on the
raised face of the flange when the gasket has been properly seated. This support
prevents damage to the flange or gasket from excessive bolt torque.”
Normally, 6BX flanges with raised faces contact when fully made up.
This improves bending resistance at the connection, and limits further
deformation of the ring gasket.
The API 6A requires that flanges integral with “drill through” equip-
ment be marked as follows:
Manufacturer’s name or mark, API monogram (when authorized by API),
flange or hub size, pressure rating, ring joint type and number, minimum vertical
bore, model and serial number and date of manufacture, and clamp number where
applicable.

4.13.2 Ring gaskets
Ring gaskets used with API flanges are identified by type and number:
• The types are R, RX, and BX.
• A number denotes the dimension or size.
Ring gaskets are available in a range of materials, and must meet the
API specification for maximum hardness to ensure that the gasket