(Newsletter: Feb. 2026)
From Rail to Reactor – Custom Propylene Offloading Solution for a Client Supplying Feedstock to a Dow Plant in Louisiana
At S&S Technical, we pride ourselves on developing fully integrated, engineered-to-order solutions that help our clients move product safely, efficiently, and without interruption. One of our latest projects highlights exactly that.
A valued S&S client is supplying propylene via railcar from their Texas facility to a Dow site in Plaquemine, Louisiana. With no on-site storage available at the Dow plant, the challenge was clear: design a reliable, redundant system that could offload railcars and deliver propylene directly into Dow’s process unit – safely and continuously.
S&S delivered two fully integrated skids engineered specifically for this application.
Propylene Railcar Offloading Compressor Skid
The compressor skid is designed to offload propylene from incoming railcars and transfer it to the downstream surge drum and pump system.
The skid is built for Propylene Offloading Service in accordance with:
- ASME B31.3 piping code
- AWS D1.1 structural standards
- Class 1, Division 1 electrical classification due to where is had to be installed
Major Components & Highlights:
- Blackmer HD362C A/B Compressors – Providing full redundancy
- ASME Tank Assembly
- 300# class carbon steel piping
- Rosemount instrumentation
- Powder-coated piping with galvanized structural steel skid frame
- Hydrotested to 1.5x design pressure
- 5% X-ray NDT on butt welds
The dual-compressor configuration ensures Dow can continue unloading operations even during maintenance or an unexpected equipment issue. Eliminating downtime was a key driver in the design.
The compressor skid moves propylene vapor to assist in railcar evacuation and directs liquid product forward to the surge drum located on the pump skid.
Propylene Pump Skid with Surge Drum
With no bulk storage at the Dow site, S&S engineered the pump skid to receive product from the compressor skid and immediately forward propylene into the plant’s process unit.
Major equipment included:
- 3,000 Gallon Propylene Surge Drum
- Vent Blowdown Drum
- (2) SERO Side Channel Pumps
- (2) 50HP BALDOR XPFC Motors
- Galvanized steel skid frame
- Rosemount instrumentation
- Fisher control valves
The pump skid takes liquid propylene from the surge drum and delivers it directly into Dow’s process unit in real time.
Built-In Redundancy
Two pumps were incorporated to eliminate single points of failure. In continuous chemical production environments, uptime is everything. This duplex configuration allows one unit to operate while the other remains on standby, ensuring uninterrupted product flow.
Why Propylene Matters at Dow
Propylene is a critical petrochemical feedstock used to produce polypropylene, propylene oxide, acrylonitrile, and other derivative products essential to plastics, coatings, fibers, and industrial chemicals. For facilities like Dow’s Plaquemine site, consistent feedstock delivery is crucial to maintaining downstream production.
Without on-site storage, the railcar-to-process design required careful coordination between vapor recovery, surge capacity, and pumping to maintain safe and stable operation.
Engineered for Hazardous Environments
Both skids were designed for Class 1, Division 1 hazardous area classification and fabricated to meet strict code requirements. Every detail was engineered with safety, compliance, and reliability in mind.
The S&S Advantage – One-Stop-Shop Execution
This project is a perfect example of how S&S works alongside its clients:
- In-house mechanical and electrical engineering
- 3D modeling and layout optimization
- ASME pipe fabrication and structural fabrication
- Integrated automation and control systems
- Factory Acceptance Testing (FAT) prior to shipment
- Single point of contact from concept to commissioning
By developing both skids as an integrated system, S&S eliminated the need for multiple vendors and reduced installation and startup time at the Dow site.
From Texas Railcars to Louisiana Process Units
This dual-skid system demonstrates how S&S Technical helps clients move product across state lines and into live process units – safely, efficiently, and without storage constraints.
When your project requires:
- Railcar unloading
- Liquefied gas transfer
- Hazardous area compliance
- Redundancy to eliminate downtime
- Custom engineered skid packages
S&S Technical delivers turnkey solutions built around your process.
Have a railcar unloading or liquefied gas project coming up?
Let’s talk about how we can engineer a custom skid solution tailored to your site.