API6B/6BX ANSI Weld Neck Flange Slide Rule
| Flange Size/Rating | Weld Neck Dimensions (Inches) | Flange-Material and PSI Yield (K) | Matching ANSI pipe size, schedule & yield PSI (K) | ||
| OD | ID | H | |||
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| *Indicates a heavier schedule pipe may be required - check pipe CWP with your pipe supplier. Items shown with asterix indicates a higher schedule could be required as follows:- |
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| *1 | Sched 80 | *2 | Sched 100 | *3 | Sched 120 | *4 | Sched 140 |
| *5 | Sched 160 | *6 | Sched XXS | *7 | Custom Pipe | ||
’Obsolete’, ’discontinued’ or ’withdrawn’ API flanges have not been included in the above slide rule.
Important note:- the above slide rule assumes ambient temperatures. Additionally,
as temperatures rise, the cold working pressure
(CWP) rating reduces.
Consult API and ASME pressure/temperature charts.
API6B/API6BX Weld Neck Flanges have restricted bores to match standard ANSI/ASME pipe sizes and schedules. API5L/ASTM carbon steel line pipe is lower yield than API6A flanges therefore a heavier wall is required. API6B/API6BX flanges should have a matching metallurgical chemical composition to suit API5L/ASTM pipe. In API6B 2,000 to 5,00 psi GSL stocks 45k and 60k rated weldneck flanges in high yield carbon and low alloy steel that are compatible with AI06B/API5L ASTM pipe. Blind 6B flanges must be 4130 or 4140 (or 410SS) low alloy steel. We also stock API 10,000 psi API6BX bit in 4130/4140 grade in 60k and 75k. 10,000 and 15,000 psi API6BX flanges are manufactured in low alloy steel 4130 or 414 stainless hence higher grade equivalent pipe will be required. API Spec 6A does not provide specifications for 6B/6BX Weld Neck Flanges in sizes above 11". The above chart shows unofficial 6B Weld Neck Flanges in some common sizes over 11" as some operators require these flanges. Global Supply Line stocks API6B and API6BX flanges in high yield carbon steel as required under API standards. API6BX alloy steel flanges are also stocked.
All API6B and API6BX Weld Necks shown have a minimum wall thickness of .2 inches (5.08mm), which in many cases exceeds API requirements. 'Integral' full bore API6A weld neck flanges are available on an indent basis. They have a larger weld neck O.D. than API6B and API6BX flanges to match API6A full port valves, spools or tubular products. Even though they are weld neck, once the full bore 6A flange is welded to a spool the flanges are deemed Integral'. The Necks on these 'Loose' full bore API6A flanges do not usually match any pipe schedules. Another alternative is oversize neck flanges that mate with the next available larger pipe size up. This option is chosen when a full bore flange is required for welding onto API5L line pipe. If mating a reduced bore API6B/API6BX flange to a full bore integral flange, Global Supply Line can counter bore the reduced bore API6B or API6BX flange to match the full bore API6A flange (see illustration table l below).
API Spec 6A does not specify overall height of 6BX weld neck flanges, only dimensions of each section of the flange. There are also allowable inbuilt tolerances and the bevel height is undefined. Consequently, the above height for API6BX Flanges is an approximate dimension only.
In the above slide rule, the required schedule recommended of equivalent seamless carbon steel line pipe is based on the minimum yield shown (example 35,000 psi (35K) yield strength). The cold working pressure (CWP) of seamless carbon steel line pipe can vary between various grades and standards (and can be interpreted differently). Typically ANSI B31.1 and B31.3 line pipe is most commonly available in ASTM A106-B, API5L-B and ASTM A53. Cold working pressures vary and standards are continuously being changed hence the above table is only to be used as a guide.
Only use seamless line pipe 35K yield or greater.
Upon examining the CWP of API5LB/A106-B line pipe, the optimum wall size has been shown in the above slide rule. However users should check the CWP of pipe purchased, the above table is only a guide. Utilising high yield API5LX52 line pipe will allow a lighter wall thickness and therefore a larger bore.
The above slide rule shows the equivalent ASTM ’nominal bore’ size. ASTM - ANSI pipe sizes are based on a ’nominal bore’ where as API6A sizes are based on the full port through bore through bore size. However, you will see in our other API slide rule, equivalent ANSI sizes to mate with API sizes. Whilst in many sizes the flanging is the same, the rating of ANSI/ASTM flanges and pipe is lower, hence this slide rule shows possible schedule interelations that ensure API6A cold working pressure ratings are not compromised. API and ASTM/ANSI pipe sizes also share common O.D’s in many sizes. The reason for this is that ANSI and API standards share a common ancestry. API6A now being the upstream standard has of course since increased pressures and ratings but the lower old API ’series’ ratings are now known as ANSI/ASME ‘class’ and have continued to be used down stream for applications which now fall under ASME/ANSI/ASTM standards.
As ASTM seamless line pipe is readily available and low cost, Global Supply Line stocks API6B and API6BX flanges in heavy schedules enabling GSL Engineering Division to machine weld necks to match required pipe schedule. This is an ideal solution for applications other than the main wellhead where full API port is not required. Furthermore, for the same reasons, carbon steel A234WPB buttweld tees, elbows and reducers can then also be used which are readily available in the same welding compatible material as 45K flanges. These fittings are also stocked by Global Supply Line in the same range of schedules.
The API6B & API6BX flanges Global Supply Line stock are available to NACE MR-01-75 as it applies to down stream line pipe and refinery requirements. This does not allow a high level of H2S as may be specified for higher wellhead components which are rated ’H2S’ service. Unlike API6A full port flanges they are not manufactured from 4140 or 4130. Being carbon steel they are weld compatible with carbon steel pipe A134 WPB fittings and ASTM line pipe such as 5LB, A106B etc. API6B requires that Blind flanges and Companion flanges are 60k yield. Global Supply Line stocks ’DD’, PSL1 ( API-2) to allow welding compatibility, API6B weldneck flanges are supplied as 45K (’DD’, PSL1, type 4). Ease of weldability is ensured as these flanges are dual conforming to the carbon steel chemical composition of mating ASME/ANSI piping components such as A105N/A106B/A234 WPB etc. Similarly API6BX 10,000 psi flanges are stocked in 75K yield in Blind and Companion (‘DD‘, PSL2 API-3) and 60K yield in weldneck (‘DD’, PSL2, API-2).
Beware, some suppliers and manufacturers supply standard A105N material flanges stamped as 3000 or 5000, these flanges interconnect with API sizes (example a 2” ANSI A105 1500 class flange rated at 3700 psi CWP is the same as a 2” 5000 API 5000 psi CWP flange) but as A105 flanges are only 36,000 psi yield they are not rated to API cold working pressures. For instance, high yield 45K A105 flanges are required for weldneck flanges 2m to 5m. However, blind and companion flanges must be 4130/4140/1040 low alloy steel even in 2m to 5m.
Global Supply Line also stock hammer unions in 4130 and 4140. However, for ease of welding we also stock buttweld hammer unions with forged A105N carbon steel welding ends up to 6000 psi in 2” up to 3000 psi in 3”and up to 2000 psi 4” to 8”. A105N is an equivalent, compatible grade of carbon steel to ANSI carbon steel line pipe, fittings and flanges mentioned above.
Information at this website is only to be used as a general guide and we do not guarantee it’s correctness. This information should not be used for any operational or engineering decision and Global Supply Line is not liable in any way. Anyone using information at this website does so at their own risk and assumes all liability.
Types of API6A/6B/BX Flanges, Spools, Adaptors & Connectors
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