MSS - Manufacturers Standardization Society of the Valve and Fittings Industry.
Scope
This standard practice covers design requirements@ test performance@ marking requirements@ and nomenclature for butterfly valves designed for high pressure performance@ having a seat plane offset from the plane of the stem centerline. This standard practice covers flangeless (wafer type) and single flanged (lug type) body designs@ compatible with ASME/ANSI B16.5 flanges for sizes NPS 3 (DN 80) through NPS 24 (DN 600) and ASME/ANSI B16.47 Series A flanges for sizes NPS 30 (DN 750) through NPS 48 (DN 1200). Reference Tables 1 and 2. This standard practice covers valves having body pressure temperature ratings in accordance with ASME/ANSI B16.34. Definitions may be found in MSS SP 96.