In-ground Sulfur Seal for SRU Rundown Lines


Historically, the oil and gas industry has used two types of devices to achieve a vapor seal in sulfur rundown lines. The first type is an in-ground sealing device that is commonly referred to as a sulfur seal leg. This traditional device has been utilized in SRU’s for over 50 years. The second type is an above-ground sulfur sealing unit. Our SxSeal® 1000 and SxSeal® 2000 are two perfect examples of above-ground devices.

During normal operation, liquid sulfur flows into the seal leg via a rundown. Once inside the device, sulfur flows downward through the inlet piping to the bottom of the leg, and then upward through the annular outlet piping to the sulfur outlet.  Similar to a P-trap, liquid sulfur in the bottom of the seal leg establishes a vapor seal, preventing H2S and SO2 vapor from passing into the sulfur pit or collection vessel.


  • Prevents H2S and SO2 vapor from passing to sulfur pit or collection vessel
  • Supplemental pressure relief path