API 6A type 6BX flange dimension and integral transition piece.

SaRaKr · Mar 15, 2016

Hi members

Refernce: API 6A type 6BX 10K PSI flange
Flange SIZE RANGE: 4-1/16, 11, 13-5/8.
Pipe size: NPS 4, 14, 16 respectively ASME B36.10

Background;
API 6A 2010 does not recommend transition pieces to match flange 'small diameter of hub J2' with ASME B36.10 PIPES. However the total length of flange is also no finalized in API 6A.

Query
1. Why does code does not finalize total height of flange.
2. What is the significance of indicating minimum 6mm after length of hub J3. i.e who will finalize the length and based on what parameters.
3. Why was the requirement of transition pieces removed from API 6A to match pipe OD.
4. Can a API 6A type 6BX 10k PSI flange ends be tapered to match ASME B 36.10 pipes as per API RP 14E APPENDIX B without using transition piece. (Can API 6A-monogram be used for the flange after tapering?)

Please share ur opnion/experince.
Thanks in advance

jmec87 · Mar 15, 2016

1. Spec 6A allows purchasers and manufacturers to agree on the final length of the flange.
2. Any length 6mm or longer is sufficient. It is up to the purchaser and manufacturer to agree on the length based on their design requirements and/or their stock.
3. You'd have to ask the committee that made the change.
4. The flange ends can be tapered to match the pipe sizes, but then the manufacturer has to do design calculations to ensure that it is suitable for the rated pressure and it generally could not be API 6A monogrammed. To apply the API 6A monogram, all API 6A requirements must be met, including all dimensional requirements. Therefore, if you change the flange end so that it doesn't meet the API 6A requirements, it cannot be API monogrammed.

Some information that might be helpful to you is available from an API 6A equipment manufacturer at the following links:

http://www.woodcousa.com/about_wnf.htm

http://www.woodcousa.com/q_a-r_16.htm

http://www.woodcousa.com/q_a-r_37.htm

http://www.woodcousa.com/q_a-r_45.htm