BNL’s revolutionary TwinLine Double Door Check Valve is designed specifically for the stringent requirements of nuclear power plant service. The TwinLine check valve is a “drop-in” replacement for older API 594 duo-type check valves, with rugged simplified construction for longer service life and ease of maintenance.

The Twinline check valve’s patented design features two individually hinged outward opening doors (discs). Each door is supported by a separate shaft, which then connects with two power springs biased to the closed direction. Because the hinges and springs are located outside of the flow path, the possibility of damage to these parts is greatly reduced. Furthermore, the springs are captured entirely by the insert ring, eliminating any possibility that broken springs can enter the pipelines.

Excellent candidate for applications where a non-slam check valve is necessary to meet backflow prevention requirements.

  • Outward-opening discs for uniform flow passage and easier position determination.
  • Two recessed power springs on each disc for greater reliability.
  • One-piece seat insert, metallic elastomer, out of flow stream for longer service, and readily replaceable with no special tools or processes.
  • Provision for position monitoring with magnetic, acoustic, or ultrasonic sensors.
  • No pressure boundary penetrations for greater leak tightness.

SIZES: 8" through 30"

ENDS: Wafer, Lug

ANSI CLASS: 125, 150, 300, 600

MATERIAL: Body, Disc: Stainless Steel, Monel, Titanium, AL-6XN, Alloy 20, Hastelloy, and others upon request

SEAT: EPDM, Viton, Buna, Metal

ANSI/ASME B16.34
ASME Section III, with or without N-Stamp. (All code editions and addenda)
Copyright 2012 - BNL Industries, Inc.
BNL Industries, Inc., 30 Industrial Park Road, Vernon, CT 06066 - ph: 860-870-6222  fx: 860-870-6221