Heat treatment requirements for forgings on FPSO

When Haihao Group received the customer’s FPSO order, the customer made detailed requirements for the product, including the requirements for heat treatment:

Forgings must be normalized, normalized and tempered, or tempered and tempered after forming. Heat treatment should be carried out in accordance with a documented procedure. For each heat treatment, it is necessary to keep a record (heat treatment table), which should be included in the act of acceptance control, if this is determined by the technical conditions.

Heat treatment should be carried out in a special oven, which is kept in proper condition and equipped with the necessary temperature control devices. The furnace dimensions and heating equipment must ensure that the entire furnace load is evenly heated to the required temperature for the entire volume and duration of delivery.

Heat treatment should be carried out using equipment that has been calibrated and inspected no more than 1 year before the start of production.

The oven temperature must be controlled within ± 10 °C.For each batch of products undergoing heat treatment, the heating/cooling rate, the holding temperature and the duration of languor at each stage of the heat treatment cycle should be indicated.

A minimum of two contact thermocouples should be provided for each batch of heat-treated products: one should be located in the center of the batch of heat-treated products, the other in the corner of the batch of heat-treated products, next to the oven door. For each batch of products undergoing heat treatment, at least one contact thermocouple must be connected to all tread-protected forgings and/or the tread-protected test ring (or sample-mounted forgings) during the entire heat treatment cycle to allow monitoring and continuous recording of their temperature. The holding time starts from the moment when the last contact thermocouple reaches the specified holding temperature. It is necessary to adjust the heating rate to minimize the time it takes for the first and last contact thermocouple to reach the specified temperature. 

The tempering temperature for the ASTM A694 material should be between 540 and 650 °C.

For water-hardened C-Mn steel parts, the time between removing the parts from the furnace and submerging them in the quenching medium should not exceed 90 seconds. The water should be mixed, preferably in a cross flow, to ensure fast and correct quenching. The initial and final temperature of the cooling water must be recorded and must not exceed 40 °C.

Heat treatment equipment must be calibrated at least once a year to ensure the necessary temperature stability and uniformity.

It is forbidden to stack forgings. A minimum distance of 100 mm between forgings must be ensured. It is forbidden to mix forgings with forgings from other purchase orders.

The heat treatment should be completely traceable, i.e. it should be possible to track the corresponding batch of heat treatment and the heat treatment table by a unique forging number.

Haihao Group carries out heat treatment for forgings in strict accordance with customer requirements. Our company has obtained the certification of five major classification societies in the world, and the products are widely used in subsea pipeline, FPSO, LNG and other projects. If you need pipe fittings for related projects, please feel free to consult us.