A Malleable Iron Fitting is defined as Cast fittings and these are for low pressure fittings. These as well constitutes joining of low pressure piping systems by Screwed connections they are generally BSPT or NPT type.
 

Common Types:  
• BLACK and GALVANISE
• NPT, BSPT and ANSI #150 AND #300
• Elbow 90 , Elbow 45 ,
• Straight Elbow , Reducing Elbow ,
• Tee, Reducing Tee ,
• Cap , Union , Hex Nipple
• Plug , Coupling
• Reducing Coupling
• Bushing

Size Range:
• 1/8" to 6" for #150 Materials.
• ½" to 2" for  #300  Materials.

Common Materials:

Malleable Iron-ASTM A197 

Dimension / Tolerance Standards:
•   ANSI B2.1,BS21 AND DIN 2999 FOR #150.
•   ANSI B2.1 AND BS21 FOR #300.