Problems with Sulfur Removal Unit Causes a Stink

Insurance Claim, North America

An abrupt natural gas plant shutdown due to a power outage caused major equipment damage, and a faulty repair followed. The failed repair required additional material replacement and repairs. Baker & O’Brien was retained to assess the circumstances of the initial equipment failure and evaluate the cause of damages during the repair. Our expert report was used during the mediation hearing, and the parties settled the claim.

“Raw” natural gas from production wells is primarily methane. However, this raw gas contains small amounts of other hydrocarbons and contaminants such as water, carbon dioxide, and hydrogen sulfide (H2S). Gas processing plants remove these contaminants and purify the raw gas to meet market specificatons . Some recovered contaminants, such as the sulfur in H2S, have value. Operators use Sulfur Recovery Units (SRU) to convert the sulfur contained in the H2S (an invisible gas) to elemental sulfur (a yellow solid). Nearly all SRUs employ the Claus process, which uses a reaction furnace combined with a waste heat boiler.

A sudden shutdown at a natural gas plant due to a power failure resulted in significant damage to a large tubesheet inside the SRU reaction furnace/waste heat boiler. Replacing the tubesheet required welding it in place and then completing a stress-relieving step to remove internal stresses in the replacement material. After these steps, the replacement tubesheet was found to be warped, such that it was unusable. Consequently, a second replacement tubesheet was installed, this time successfully.

Baker & O’Brien was engaged to (1) assess the circumstances associated with the initial tubesheet damage, (2) review the procedures and processes used during the first tubesheet replacement, including the stress relieving process, and (3) evaluate if improper workmanship or something else caused the warping of the first replacement tubesheet. We developed an expert report and participated in a mediation hearing, after which the parties settled the claim.

Cliff Moore

Senior Consultant

Natural Gas and NGLs
Accident / Incident Investigation / Engineering, Procurement, and Construction (EPC) / Standard of Care / Insurance Claims / Operations and Maintenance