There are two generic types of drain systems that have been proven in service:-

(1) Drain Hose :The hose construction comprises high tensile textile cords, an embedded steel helix wire reinforcement to prevent vacuum collapse, and an outer cover of specially formulated synthetic polymers.

The hose is supplied with a lead coated, stainless steel ballast cable to ensure that the hose exhibits no tendency to kink when submerged.

To facilitate installation and flange alignment a continuous longitudinal stripe is incorporated in the hose cover.

The hose is designed for total immersion in petroleum products and provides a relatively inexpensive alternative to the traditional steel pipe articulated drain system.

(2) Articulated Drain Systems : A system comprising steel pipes with swivel joints, designed to withstand the forces to which it may be subjected under all operating regimes.
The system usually incorporates Heavy duty swivel joints but several alternatives are available to suit client preference.
The system is supplied with full detailed drawings and installation instructions.

Wax Scrapers

Wax Scrapers are used where crude oil with a high wax content is being stored. There are two traditional methods of removing the wax build up from the tank shell.

(1) Mechanical shoe type: Where a mechanical shoe seal is fitted wax scraper plates can be attached to the existing shoeplates. Ideally these extend the full height of the shoeplate to enable them to be replaced if necessary with the tank in service. Lower cost designs do exist that are simply bolted to the bottom edge of the shoeplate. The effectiveness of this system is dependant upon the pressure exerted by the seal against the tank shell.

(2) Tubeseal type: On tanks fitted with liquid or foam filled seals a separate wax scraper system is used. This is attached to the floating roof and uses hairpin springs to force the scraper blades against the tank shell. Originally designed for use with Tubeseals, but can be used with any type of foam seal or double compression plate seal.