Gas processing plant damage mechanism review

Client challenge

Our client contacted us to perform a damage mechanism review (DMR) on its gas plant from feed inlet to storage products, mainly propane, butane and near gasoline hydrocarbons. The end goal was risk analysis of the assets plant wide.

Field data collection for equipment and piping was also included in the scope as the client wanted us to assist with PCMS upload sheet effort for the entire plant that included design and operating conditions also. Review of piping and instrumentation diagrams (P&IDs) was required for collection of the data in-depth. Various units like amine treating, sulfur recovery unit (SRU), dehydration, liquefaction and storage were involved.

The feed obtained was raw gas from the shale fields and the feed which was obtained at low pressure, was pressurised using three stage compressors prior to amine treating. The raw gas containing higher amounts of liquids was separated and distilled to obtain lighter components and liquid hydrocarbons separated were sent to pentane/gasoline storage bullets to be sold as products to other plants for processing.

How we helped

DMR for the entire facility was a challenging task involving review of process service conditions, materials of construction, previous inspections and history of operation as required to assess risks for each unit from corrosion and cracking possibilities. Probability of failure was identified when cracking risk was identified so inspection planning can occur in a timely manner to detect the issue proactively.

Presence of corrosive agents and toxins in the feed and their impact on various separation, distillation, treating equipment and high temperature heaters was critical, in assessing possibility and probability of damages.

After the treatment of the lighter hydrocarbon components, their liquefaction train was important to assess for brittle fracture. Material of construction details for review were essential for those sections of the plant to understand proper metallurgy is chosen at design phase to mitigate the risk.

The risk of upgraded metallurgy selection for equipment like brazed aluminum heat exchangers (BAHX) was assessed for toxin risks posed by compounds like mercury amalgamates.

A field visit was performed at the start of the project to collect field data along with P&ID review and piping specifications to assess design and operating conditions required for PCMS upload sheet effort for risk analysis.

Powerful results

The review performed by Vysus Group noted corrosion rates along with possible damage mechanisms relevant for each unit. Corrosion rate plays a role in understanding the service life and cracking damage mechanism and its probability helps plan for inspections to catch the defect early on. Aggressive corrosion prone assets in the SRU were reflected to show higher risks and precautions in these units during downtimes to avoid failures during startups. The separation, distillation sections related assets from the wet feed were noted with higher corrosion rates to indicate maximum expected service life for those assets for client to be able to timely replace them with least downtime.

The gas treating unit having several corrosion problems due to operational as well as materials issues was highlighted and upgrade in metallurgy in selected areas in piping segments were informed to help reduce consistent wall loss and replacements in the unit. Storage spheres were reviewed thoroughly and brittle fracture assessment was performed in-depth for client due to high value nature of the large propane and butane storage spheres.

Risk was reduced after the review when the client had input the data into the risk-based software after our assessment notes.