TP316L Feedwater Heater Tubes for Java-7 Power Plant

Java-7 Power Plant

The Java-7 power plant, Indonesia.

The Java-7 power plant (also called PLTU Jawa 7) is a 2,100 MW coal-fired power plant (CFPP) comprised of two units located at Terate Village, Kramatwatu District, Serang Regency, Banten Province, Indonesia. This project is located on the island of Java, Indonesia, with a total investment of more than US$1.88 billion and a total installed capacity of 2×1050MW. Upon completion, the project is expected to generate 15 billion kWh of electricity each year, which will effectively improve power supply in Indonesia, greatly alleviate the electricity shortage on Java island, and drive local economic growth and social development. The Java-7 project, which is a steam turbine power plant, was developed by PT Shenhua Guohua Power Jawa Bali. China Shenhua Energy and PT Pembangkitan Jawa-Bali are currently owning the project having ownership stake of 70% and 30% respectively. The project construction commenced in 2016 and subsequently entered into commercial operation in December 2019.

Feedwater Heater Tubes

Packaging of ASTM A688 TP316L U-tubes for feedwater heaters which are used in the Java-7 power plant. All tubes are seamless.

A feedwater heater is an important component used in power plants to increase the temperature of water before it enters the boiler. The tubes used for the fabrication of the feedwater heater shall be made in accordance with ASTM A688. These feedwater heater tubes shall be made from a wide variety of austenitic stainless steels, which offers excellent corrosion resistance and high-temperature strength. Metalsin Tech has engaged in the supply of ASTM A688 TP316L feedwater heater U-tubes to the Java-7 power plant.

Chemical Composition Requirements

• Carbon (C): ≤ 0.035%
• Manganese (Mn): ≤ 2.00%
• Phosphorus (P): ≤ 0.040%
• Sulfur (S): ≤ 0.030%
• Silicon (Si): ≤ 0.75%
• Chromium (Cr): 16.00% – 18.00%
• Nickel (Ni): 10.00% – 15.00%
• Molybdenum (Mo): 2.00% – 3.00%
• Iron (Fe): Balance

The chemical composition of ASTM A688 TP316L (UNS S31603) ensures that the tubes provide enhanced corrosion resistance, particularly against chlorides and other industrial solvents, making them ideal for use in the demanding environment of feedwater heaters.

Mechanical Properties

The strength, ductility, and resistance to deformation of ASTM A688 TP316L feedwater heater tubes are as follows:

• Tensile Strength: Minimum 70,000 psi (485 MPa)
• Yield Strength (0.2% offset): Minimum 25,000 psi (175 MPa)
• Elongation in 2″: Minimum 35%

Heat Treatment of The U-Bend Area

Light oxide scale appears on the U-bend areas of ASTM A688 TP316L seamless tubes after online electric-resistance heating treatment.

These TP316L feedwater heater tubes are furnished in U-bend style. The solution-annealing heat treatment shall be applied to the U-bend area plus approximately 150 mm of each leg beyond the tangent point of the U-bend. The inside of the tube shall be purged with a protective or an inert gas atmosphere during the heating and quenching process. A light oxide scale on the outside surface of the U-bend area shall be permitted for tubes which have been electric-resistance heat treated after bending. After final annealing, the tubes shall be pickled using a solution of nitric and hydrofluoric acids followed by flushing and rinsing in water.