Case History: FRP phosphoric acid storage

CUSTOMER:

Fertilizer Plant in Indonesia.

EQUIPMENT:

2 units of FRP Phosphoric Acid Storage Tanks.

Diameter up to 20M(65.6ft), Height up to 15.8M(51.8ft), Capacity up to 5000 M3 / 9000 Tons each.

OPERATING CONDITION:

The Storage Tanks contain 85%-concentrated phosphoric acid at ambient temperature.

CONSTRUCTION:
The storage tanks was fabricated by Filament Winding, using Swancor Chempulse 901 Epoxy Vinyl Ester Resin.

Corrosion barrier was applied by hand lay up, with a laminate construction as follows: One layer of C-veil, followed by two layers of 450 g/m2 (1.5oz/ft2) chopped strand mats.

RESIN USED:

SWANCOR CHEMPULSE 901

MANUFACTURER:

PT. Gunung Putri Graha Mas, Indonesia

PT. Gunung Putri Graha Mas was chosen by a Fertilizer Plant in Indonesia to construct two 5000 m3 (1.3 M gallon), 85% phosphoric acid storage tanks at ambient temperatures. In its November  2005 issue, Reinforced Plastics Magazine believes that the two tanks – each with a diameter of 20m (65.6 ft), and a shell height of 15.8 m (51.8 ft) – are the world’s largest FRP acid storage tanks.

 

 

Designed by Alfred Newberry, of FEMech Engineering, Harrison, AR, USA, who also supplied the design of the large diameter vertical filament winder. The design-specific gravity for the tanks is 1.8, which results in a liquid head pressure of 28.4 m of water column or 282 kPa (40.4 psi).

 

 

When filled, each vessel and contents weigh in excess of 9000 tonnes. The corrosion barrier was applied by hand lay up, with a laminate construction as follows: One layer of C-veil, followed by two layers of 450 g/m2 (1.5 oz/ft2) chopped strand mats.

 

 

PT. Gunung Putri Graha Mas assigned 50 men to the project, and the fabrication was conducted on-site. FRP was selected over stainless steel because of the high cost and corrosion rate of welds in stainless steel.

 

 

Another accomplishment worth noting regarding the tanks’ fabrication was its world’s first wound-on knuckle. This was accomplished by first turning over the knuckle and setting it on the winder.

The bottom was wound onto the knuckle, which was shaped by the FEA design. Once the winding was complete, the knuckle and bottom were turned over again. We believe that a wound-on knuckle has a superior design and greatly reduces labor compared to conventional knuckle construction methods.

 

 

The dome was made in 16 segments each with a trapezoidal stiffener. The segments were joined in the center to a large C-shaped compression ring.

 

 

The shell was made in five cans using a stepped-wall design. The cans were hoop-wound and reinforced with 600 g/m2 unidirectional stitched fiberglass fabric for axial strength and stiffness. The resin used for this project was an epoxy vinyl ester resin: Swancor Chempulse 901.

 

 

The fabrication started on September 2005, construction finished at the end of June 2006. Hydro tests were accomplished on 26 August 2006, and the tanks will be operated at the end of September 2006 by the owner.