• Fully Compliant to API 609 & MSS SP-67 • Standard 416SS Shaft MATERIALS OF CONSTRUCTION. CATEGORY B CERTIFIED BY USCG TO MEET ALL REQUIREMENTS OF CFR 46. API STANDARD 609. EIGHTH EDITION. 5.7 Valve Body Seat Retainer—Category B Valves Only. MSS SP-91, Guidelines for Manual Operation of Valves.
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. Immediate download. $184.00. This standard covers design, materials, face-to-face dimensions, pressure-temperature ratings, and examination, inspection and test requirements for gray iron, ductile iron, bronze, steel, nickel-based alloy, or special alloy butterfly valves. The following two categories of butterfly valves are included.
A) Category A-Manufacturer's rated cold workingpressure (CWP) butterfly valves, usually with aconcentric disc and seat configuration. Sizes coveredare NPS 2 to NPS 48 for valves having ASME Class125 or Class 150 flange bolting patterns.
B) Category B-ASME Class and pressure-temperaturerated butterfly valves that have an offset seat andeither an eccentric or a concentric disc configuration.These valves may have a seat rating less than thebody rating. Sizes covered are listed below. For lug and wafer, Class 150: NPS 3 to NPS 48. For lug and wafer, Class 300 and Class 600: NPS 3 to NPS 48.
For double-flanged long pattern, Class 150, 300, and 600: NPS 3 to NPS 36. For double-flanged short pattern, Class 150 and Class 300: NPS 3 to NPS 48. For double-flanged short pattern, Class 600: NPS 3 to NPS 24. Valve configurations include double flanged, lug- and wafer-type with facings that permits installation between ASME and MSS flanges that conform to the standards and specifications listed in Section 2.
Typical valve construction and nomenclature for valve parts are shown in Annex C. Product Details Edition: 8th Published: Number of Pages: 36 File Size: 1 file, 780 KB Redline File Size: 2 files, 4.6 MB Product Code(s): C60908, C60908, C60908 Note: This product is unavailable in Cuba, Iran, North Korea, Syria Document History. Amendments & Errata. Browse related products from American Petroleum Institute.
You would get more responses if this is posted in Valve Engineering. However, category A valves are 'concentric' type. Also known as rubber lined butterfly valves. These are popular in low pressure systems (Class 150 or less), relatively lower cycle life, rubber liners are also good for abrasive slurry services. Category B valves are 'offset' type, meaning the shaft is offset from the disc, so they can handle higher differential pressures. Most of the offset types cause the disc to rotate freely from the seat after a few degrees of rotation, which minimizes seat wear and increases valve cycle life. The offset type can have rubber, polymer (PTFE or other), metal &graphite, or even metal seats.
Lots of variety which makes these suitable for a variety of temperatures and pressures. Note that the above is a generalization for each category, and there are many exceptions in each. A is concentric and Cat. Google the terms concentric and offset butterfly valves and you will get links to many manufacturer web sites that will have plenty of pictures and videos showing the difference. RE: API 609 - Difference between Category A and B (Mechanical) 29 Nov 14 08:16.