Types of Elbows based on Material of Construction
Stainless Steel Elbow : ASTM A403 WP Gr. 304, 304H, 309, 310, 316, 316L, 317L, 321, 347, 904L
Carbon Steel Elbow : ASTM A 234 WPB , WPBW, WPHY 42, WPHY 46, WPHY 52, WPH 60, WPHY 65 & WPHY 70.
Low Temperature Carbon Steel Elbow : ASTM A420 WPL3, A420 WPL6
Alloy Steel Elbow : ASTM / ASME A/SA 234 Gr. WP 1, WP 5, WP 9, WP 11, WP 12, WP 22, WP 91
Duplex Steel Elbow : ASTM A 815, ASME SA 815 UNS NO S31803, S32205. Werkstoff No. 1.4462
Nickel Alloy Elbow : ASTM / ASME SB 336 UNS 2200 ( NICKEL 200 ), UNS 2201 (NICKEL 201 ), UNS 4400 (MONEL 400 ), UNS 8020 ( ALLOY 20 / 20 CB 3, UNS 8825 INCONEL (825), UNS 6600 (INCONEL 600 ), UNS 6601 ( INCONEL 601 ), UNS 6625 (INCONEL 625), UNS 10276 ( HASTELLOY C 276 )
Some Other Types of Elbows
In addition to the above defined elbows there are few more types of elbows which are not used on regular basis. Few of them has been defined below.
A reducing elbow is a type of fitting which is used to join two pipes of different sizes. The reducing elbow is so called because it looks like a reducing piece and elbow combined into one. The reducing elbow eliminates one pipe fitting (reducer) and reduces the welding by more than one-third. Also, the gradual reduction in diameter throughout the arc of the reducing elbow provides lower resistance to flow and reduces the effect of stream turbulence and potential internal erosion. These features prevent sizable pressure drops in the line.
For many suppliers it is a non standard item resulting into high price with a long delivery time. The use of a “normal” elbow with a separate reducer is an option if the situation allows.