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Three types of end and outlet flanges are covered by this International Standard: Types 6B, 6BX and segmented.
Types 6B and 6BX flanges may be used as integral, blind or welding neck flanges.
Type 6B may also be used as threaded flanges. Some type 6BX blind flanges may also be used as test flanges. Segmented flanges are used on dual completion wells and are integral with the equipment.
10.1.2 Design
10.1.2.1 Pressure ratings and size ranges of flange types
Type 6B, 6BX, and segmented flanges are designed for use in the combinations of nominal size ranges and rated working pressures as shown in Table 35.
Table 35 — Rated working pressures and size ranges of flanges
Flange size range Rated working pressure
MPa (psi)
Type 6B
mm (in)
Type 6BX
mm (in)
Dual segmented
mm (in)
13,8 (2 000) 52 to 540 (2 1/16 to 21 1/4 ) 680 to 762 (26 3/4 to 30) —
20,7 (3 000) 52 to 527 (2 1/16 to 20 3/4 ) 680 to 762 (26 3/4 to 30) —
34,5 (5 000) 52 to 279 (2 1/16 to 11) 346 to 540 (13 5/8 to 21 1/4 ) 35 to 103 ¥ 108 (1 3/8 to 4 1/16 ¥ 4 1/4 )
69,0 (10 000) — 46 to 540 (1 13/16 to 21 1/4 ) —
103,5 (15 000) — 46 to 476 (1 13/16 to 18 3/4 ) —
138,0 (20 000) — 46 to 346 (1 13/16 to 13 5/8 ) —
10.1.2.2 Type 6B flanges
10.1.2.2.1 General
Type 6B flanges are of the ring joint type and are not designed for face-to-face make-up. The connection make-up bolting force reacts on the metallic ring gasket. The type 6B flange shall be of the through-bolted or studded design.
10.1.2.2.2 Dimensions
a) Standard dimensions
Dimensions for type 6B integral, threaded, and welding neck flanges shall conform to Table 36*, Table 37* and Table 38*.
NOTE The data in tables marked with an asterisk are repeated in US Customary units in Annex B (with the same table number as in the main body of this International Standard, but with the prefix B).
Dimensions for type 6B blind flanges shall conform to those referenced in Figure 8.
NOTE 1 See Tables 36*, 37* and 38* for dimensions B and T and for dimensions not shown. For E dimensions, see Tables 50* and 51*.
NOTE 2 Raised face and/or counter-bore are optional.
a Optional. b Counter-bore.
Figure 8 — Type 6B blind flanges
Dimensions for ring grooves shall conform to Table 50* or Table 51*.
b) Integral flange exceptions
Type 6B flanges used as end connections on casing and tubing heads may have entrance bevels, counter-bores or recesses to receive casing and tubing hangers. The dimensions of such entrance bevels, counter-bores and recesses are not covered by this International Standard and may exceed the B dimension given in Tables 36*, 37* and 38*.
c) Threaded flanges
Threads shall conform to the requirements of 4.2.1.2.
d) Welding neck flanges
1) Bore diameter and wall thickness: The bore diameter JL shall not exceed the values shown in Tables 36*, 37* and 38*. The specified bore shall not result in a weld-end wall thickness less than 87,5 % of the nominal wall thickness of the pipe to which the flange is to be attached.
2) Weld end preparation: Dimensions for weld end preparation shall conform to Figure 9 (see Figure B.9 for US Customary units).
3) Taper: If the nominal bore of the welding end is smaller than the nominal bore of the pipe by a difference of 4,8 mm (0,18 in) or more, the flange shall be taper bored from the weld end at a slope not exceeding 3 to 1. However, requirements for minimum wall thickness shall apply.
NOTE Due to smaller maximum bore dimensions, Type 6B welding neck flanges are not intended to be welded to equipment specified in this International Standard. Their purpose is to bolt to another 6B flange and provide a transition to be welded to a pipe.
10.1.2.2.3 Flange face
The flange face shall be flat or raised on the ring joint side and shall be fully machined. The flange back face may be fully machined or spot-faced at the bolt holes. The flange back face or spot faces shall be parallel to the front face within 1° and the thickness after facing shall conform to the dimensions of Tables 36*, 37* or 38*.
Type 6B flanges shall use type R or type RX gaskets in accordance with 10.4.
10.1.2.2.5 Corrosion-resistant ring grooves
Type 6B flanges may be manufactured with corrosion-resistant overlays in the ring grooves. Prior to application of the overlay, preparation of the ring grooves shall conform to the dimensions of Table 39*. Other weld preparations may be employed if the strength of the overlay alloy equals or exceeds the strength of the base material.
10.1.2.2.6 Ring groove surface
All 23° surfaces on ring grooves shall have a surface finish no rougher than 1,6 µm Ra (63 µin RMS).
10.1.2.3 Type 6BX flanges
10.1.2.3.1 General
Type 6BX flanges are of the ring joint type and are designed with 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. Therefore one of the flanges in a 6BX connection shall have a raised face. The type 6BX flange shall be of the through-bolted or studded design.
NOTE Face-to-face contact is not necessary for the proper functioning of type 6BX flanges.
10.1.2.3.2 Dimensions
a) Standard dimensions
Dimensions for 6BX integral flanges shall conform to Table 40* or 41*, as applicable.
Dimensions for 6BX welding neck flanges shall conform to Table 42* or 43*, as applicable.
NOTE These flanges are not available in all the same pressure ratings and sizes as the integral flanges.
Dimensions for 6BX blind and test flanges shall conform to Table 44*, 45* or 46*, as applicable.
b) Integral flange exceptions
Type 6BX flanges used as end connections on casing and tubing heads may have entrance bevels, counter-bores or recesses to receive casing and tubing hangers. The dimensions of such entrance bevels, counter-bores and recesses are not covered by this International Standard and may exceed the B dimension of the tables.
c) Welding neck flanges
Dimensions for the weld end preparation shall conform to Figure 9 (see Figure B.9 for US Customary units).
a) For neck thickness t uuuu 22 mm b) For neck thickness t >>>> 22 mm
Figure 9 — Weld end preparation for type 6B and 6BX weld neck flanges (see Annex B for US Customary units)
10.1.2.3.3 Flange face
The flange face on the ring joint side shall be raised except for studded flanges which may have flat faces. Front faces shall be fully machined. The nut bearing surface shall be parallel to the flange gasket face within 1°. The back face may be fully machined or spot-faced at the bolt holes. The thickness after facing shall conform to the dimensions of Tables 40* through 45*, as applicable.
10.1.2.3.4 Gaskets
Type 6BX flanges shall use BX gaskets in accordance with 10.4.
10.1.2.3.5 Corrosion-resistant ring grooves
Type 6BX flanges may be manufactured with corrosion-resistant weld overlays in the ring grooves. Prior to application of the overlay, preparation of the ring grooves shall conform to Table 39*. Other weld preparations may be employed if the strength of the overlay alloy equals or exceeds the strength of the base material.
10.1.2.3.6 Ring groove surface
All 23° surfaces on ring grooves shall have a surface finish no rougher than 0,8 µm Ra (32 µin RMS).
10.1.2.4 Segmented flanges
10.1.2.4.1 General
Segmented flanges are of the ring joint type and are designed with a recessed face. Depending on tolerances and when the gasket has been properly seated, the connection make-up bolting force can react on the surface outside the recessed face of the flange. This support prevents damage to the flange or gasket from excessive bolt torque. The segmented flange shall be of the through-bolted or studded design.
NOTE Face-to-face contact is not necessary for the proper functioning of segmented flanges.
Segmented flange dimensions shall conform to Table 47*. Ring groove dimensions shall conform to Table 51*.
10.1.2.4.3 Flange face
The flange face shall be fully machined. The nut-bearing surface shall be parallel to the flange gasket face within 1°. The back face may be fully machined or spot-faced at the bolt holes. The thickness after facing shall meet the dimensions of Table 47*.
10.1.2.4.4 Gaskets
Segmented flanges shall use RX gaskets in accordance with 10.4.
10.1.2.4.5 Corrosion-resistant ring grooves
Segmented flanges shall not be manufactured with corrosion-resistant ring grooves.
10.1.2.4.6 H2S service
These flanges shall not be used for hydrogen sulfide service for material classes DD, EE, FF and HH.
10.1.2.4.7 Installation
Segmented flanges shall be used in sets, i.e. two flanges side-by-side for dual completions. Manifolds shall be rigidly tied together to add stability to the flanges.
10.1.2.4.8 Ring groove surface
The 23° surface on ring grooves shall have a surface finish no rougher than 1,6 µm Ra (63 µin RMS).
10.1.3 Materials
Flange material shall conform to the requirements in Clause 5.
10.1.4 Testing
Loose flanges furnished under this clause do not require a hydrostatic test prior to final acceptance.
10.1.5 Marking
Flanges shall be marked to conform with Clause 8.
10.1.6 Storing and shipping
All flanges shall be stored and shipped in accordance with Clause 9.
Table 44 — Type 6BX blind and test flanges for 69,0 MPa and 103,5 MPa rated working pressures (see Annex B for US Customary units)
Dimensions in millimetres
NOTE Ring groove to be concentric with bore within 0,25 total indicator runout.
a Bolt hole centreline located within 0,8 mm of theoretical BC and equal spacing. b Q≤max. = E (Table 52);
Q≤min. = 3 mm. c Break sharp corners. d This bore optional. e Top. f Test connection. See Figure 22. g 1/2 inch linepipe or NPT threads (maximum 69,0 MPa working pressure).
Table 46 — Type 6BX blind flanges for 13,8 MPa; 20,7 MPa; 34,5 MPa; 69,0 MPa; 103,5 MPa and 138,0 MPa rated working pressures (see Annex B for US Customary units)
a Counterbore. b Maximum slope.
Dimensions in millimetres
Nominal size of flange Flange thickness Hub diameter Counter-bore depth Added hub thickness B (in) mm T J1 E J4
The requirements for loose and integral equipment end and outlet connections, including tubing and casing hangers apply only to those, which are threaded according to ISO 10422. Other loose threaded end and outlet connections are not covered by this International Standard.
10.2.2 Design
10.2.2.1 General
Internal and external thread dimensions and tolerances shall conform with ISO 10422 or ASME B1.20.1 if applicable [see 10.2.2.3].
a) Thread lengths
The length of internal threads shall not be less than the effective thread length L2 of the external thread as specified in the figure belonging to Table 48* and as stipulated in ISO 10422.
b) Internal and external NPT threads meeting the requirements of ASME B1.20.1
Pipe threads, general purpose (inch), may be used for line-pipe thread sizes 38 mm (1 1/2 inch) and smaller.
NOTE While line-pipe threads in accordance with ISO 10422 and NPT threads are basically interchangeable, the slight variation in thread form can increase wear and tendency for galling after several make-ups.
10.2.2.2 Thread clearance
A clearance of minimum length J, as illustrated in ISO 10422, shall be provided on all internal threaded equipment.
10.2.2.3 Thread counter-bores
End and outlet connections, equipped with internal threads, may be supplied with or without a thread entrance counter-bore. Internal threads, furnished without a counter-bore, should have the outer angles of 45° to a minimum depth of P/2 as illustrated in the figure belonging to Table 48* and Figure 10. Internal threads, furnished with a counter-bore, should conform to the counter-bore dimensions specified in Table 48* and the bottom of the counter-bore should be chamfered at an angle of 45°. As an alternative, counter-bore dimensions may be as specified in ISO 10422.
10.2.2.4 Thread alignment
Threads shall align with the axis of the end connection within a tolerance of ± 5,0 mm/m (± 0,06 in/ft) or 0,3° of projected axis.
10.2.2.5 End/outlet coupling diameter
The outlet coupling diameter shall be of sufficient diameter to provide structural integrity of the threaded part at rated pressure. This diameter shall not be less than the tabulated joint or coupling diameter for the specified thread.
10.2.3 Testing (gauging)
Thread gauges shall comply with the requirements for working gauges as stipulated in 4.2 through 4.6 of ISO 10422:1993. Threads shall be gauged for stand-off at hand-tight assembly. For threads manufactured in accordance with this International Standard, use gauging practices as illustrated in Figures 10, 11 and 12. For threads manufactured in accordance with ISO 10422, use gauging practices as specified in ISO 10422.
10.2.4 Marking
Threaded connectors shall be marked to conform with Clause 8.