Publish Time: 2021-12-08 Origin: Site
NDI, naphthalene diisocyanate, is prepared from naphthalene by nitration, hydrogenation reduction and phosgenation. This process was invented by Covestro, formerly Bayer, in Germany.
We are honored to participate in Covestro’s 4000 t/a NDI project in Thailand, designing and manufacturing 10 sets of phosgene heat exchangers. Because phosgene is an extremely harmful medium and no leakage of equipment is allowed, Covestro has the following high requirements for this batch of heat exchangers:
1. 20% RT for welding joints of tube to tube sheet so that no leakage during the use of the equipment.
2. The sealing surface of the tube sheet shall be secondary machining after welding to ensure the flatness of the sealing surface so as to guarantee the tightness of the equipment.
3. The whole heat exchanger does helium leak test with high sensitivity.
4. Integral heat treatment for some heat exchangers.
5. The owner, Covestro, and two third parties, TUV and Intertek, participated in the inspection and testing to guarantee the quality.
6. U stamp and NB registration are required. SGS, a testing agency, is fully involved.
In the course of 8 months' design, manufacture and inspection, we have overcome many difficulties, including COVID-19, power limitation and so on. We have successfully completed multiple tests witnessed by Covestro and the third parties and finally achieved smooth delivery.
This project tests the ability and execution of our team, and also lay a solid foundation for the in-depth cooperation between our company and Covestro on future projects.