Value Brand 1LBU6 Malleable Iron 90 Degree Elbow Class 300

Iron 90° elbow for threaded pipe

This malleable iron fitting connects two 1-1/4 inch FNPT threads at a right angle. It is rated Class 300 for saturated steam service up to 300 psi and water, oil or gas service up to 1500 psi at 150 °F. The body meets ASME B16.3, B16.4, ASTM A197 and A47 and carries FM and UL listings. Installers use it for branch lines, risers and equipment hook-ups in commercial and industrial systems.

Threaded FNPT limit at temperature

The FNPT taper threads seal with pipe dope or tape but rely on metal-to-metal engagement that can loosen under thermal cycling. At the upper end of the -20 °F to 550 °F range, differential expansion between the iron body and a steel pipe may reduce thread contact and increase leak risk. Vibration, water hammer and repeated pressure spikes also accelerate thread fatigue in this connection type.

Class 300 capacity and headroom

The 300 psi steam rating covers most low-pressure heating mains and process lines, while the 1500 psi non-shock rating provides margin for pump start-up surges in water or oil circuits. Systems that exceed 300 psi saturated steam or require sustained operation above 550 °F need a higher-class fitting or a welded joint. The 1-1/4 inch bore handles typical branch flow rates but becomes a bottleneck on high-capacity headers.