LPG Equipment

Above-ground vessels (bullets) sit on saddles or plinths in the open, which keeps installation cost lower and makes external inspection and coating maintenance straightforward, but they require larger separation distances and normally fire protection measures such as water spray or passive fire insulation. Mounded vessels are covered with a compacted sand and earth mound, which limits heat input in a fire scenario, effectively removes the BLEVE risk and allows shorter separation distances on constrained plots. Mounded installations require more civil work plus a high integrity coating and cathodic protection, since the shell is not directly accessible. The comparison depends on plot size, local regulation and inspection philosophy.

LPG storage covers small bulk vessels for single-site fuel use through to large horizontal bullets for bottling and distribution terminals. Because LPG is stored under its own vapour pressure, the usable volume is limited by the maximum permitted filling ratio, which depends on the product (propane, butane or a mixture) and design temperature. Capacity is selected from throughput, tanker payload, delivery frequency and required reserve, and is confirmed per project.

LPG vessels are commonly designed to EN 13445 in combination with PED 2014/68/EU, or to ASME Section VIII Division 1 where the US code basis is required, with AD 2000 applied in German engineering practice. EN 12542 covers small static welded steel tanks for LPG, and EN 14075 covers larger static welded tanks. Layout, separation distances and safety systems are addressed by the applicable national and installation standards, and the code set is confirmed against the country of installation.

Standard protection includes pressure relief valves sized to the code and arranged so one can be isolated for inspection, internal shut-off or excess flow valves on liquid connections, and a remotely operated emergency shutdown valve on the main lines. Level indication (float or magnetic gauge with a fixed maximum-level device), pressure and temperature indication, and a drain arrangement for water removal are also typical. Depending on layout and local regulation, water deluge, fire and gas detection and remote isolation are added. The final safety scope follows the applicable installation standard for the site.

Storage is sized on the daily filling throughput of the plant, the payload and frequency of incoming tankers and the reserve needed to keep filling running through a supply interruption or a peak season. In practice the vessel arrangement is set so it can receive a full tanker load without exceeding the maximum filling ratio, while retaining stock for continued operation. Vapour handling and pump capacity for the filling carousel are checked at the same time, since they limit effective throughput. The final figure depends on the plant and is confirmed per project.

A transfer skid is a pre-assembled package containing pumps or a compressor, isolation and non-return valves, strainers, a bypass or differential relief valve, and metering, mounted on a common frame with its piping and controls. It is required whenever gravity or differential pressure alone cannot move product at the rate needed: tanker unloading, feeding a filling carousel, transfer between vessels, or vapour return and vessel evacuation using a compressor. Skid configuration follows the required flow rate, differential head and the medium.

Coating selection follows the corrosivity category of the site, normally assessed to ISO 12944. Coastal and humid locations are typically treated as C5-M or C5-I, which calls for surface preparation to Sa 2.5 followed by a zinc-rich epoxy primer, an epoxy intermediate coat and a polyurethane or polysiloxane topcoat. Buried and mounded vessels use a higher-build system combined with cathodic protection, since the shell cannot be maintained after installation. The system is selected against site conditions and the specified durability class.

Relocation is technically possible and is done regularly, but it is a controlled sequence rather than a lift and move. The vessel must be emptied, depressurized, purged and gas-freed with an inert medium and certified safe before disconnection, and its condition and documentation are reviewed before reuse, usually including internal and external inspection and thickness measurement. At the new site, foundation design, separation distances and the applicable installation approval are reassessed. Feasibility depends on the unit, its documentation and the jurisdiction.