Choke Terminology

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Here's how to specify a BST "B" series choke!

1.  BST's "B" series chokes are first designated by the maximum trim size available in that series.  Thus, the B1 series has a maximum 1" trim, the B1.5 has 1" maximum trim, the B2 has 2" maximum, and the BE2.75 and BEL2.75 have 2" maximum trim.  See the choke specific web pages for the standard trim sizes available for each model.

2.  The "B" series designation is followed by a dash (-) and a number which reflects the nominal size of the end connections.  Thus, "2" = 2" nominal connection, etc.  See the choke specific web pages for the standard end connection sizes available for each model.

3.  The end connection designator is followed immediately by either "A" or "T."  "A" means the choke has an angle style body (the inlet is on the side and the outlet is on the bottom), while "T" means the choke has a through style body (the inlet is on one side and the outlet is directly opposite on the other side of the body).  [e.g., B1-2A]  At present, all models are available with "A" style bodies; only B1 and B1.5 models are available with "T" style bodies.

4.  The body style designator is followed by an end connection type designator.  "BW" = buttweld (followed by the desired pipe schedule; e.g., XXH, 160, 80, etc.); "LP" = API Linepipe threaded (per API Spec 5B); "NPT" = NPT tapered pipe thread per ANSI/ASME B1.20.1); "SM" = clamped hub.  If flanges are to be welded to the body, the type of flange is specified (e.g., API 5000, ANSI 1500, etc., followed by the desired pipe schedule).  All listed end connection types are available with all choke models.  [LP and NPT threads are fully compatible and may be supplied interchangeably.] 

5.  For example, the complete model designation for a B1 angle body choke with 2" NPT threads would be designated:  B1-2ANPT.

6.  The trim size, trim material (17-4 PH stainless steel or tungsten carbide), maximum operating pressure (5,000 psi is standard) and temperature (-20 to +400F is standard), and operating environment (H2S or standard) must be specified when inquiring about BST's chokes.

7.  If welding is required, let us know if welding and inspection per ANSI/ASME B31.3 is required, and if body and/or bonnet material must be Charpy tested (specify API requirement or test temperature and minimum required values.

Contact to request a Product Information Requirement Form for Adjustable Chokes.

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Last modified: January 07, 2020

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