Is it permissible to build a factory to manufacture metals used in making water pipes?

Islam has prohibited everything that harms man both physically or psychologically. God Almighty describes the believers saying, "Those who follow the Messenger, the unlettered prophet, whom they find written in what they have of the Torah and the Gospel, who enjoins upon them what is right and forbids them what is wrong and makes lawful for them the good things and prohibits for them the evil and relieves them of their burden and the shackles which were upon them" (Quran7:157). Here, right includes whatever benefits man, both physically and psychologically, while wrong include what harms him physically, psychologically, or both. God Almighty says, "Do not contribute to your destruction with your own hands" (Quran 2:195) and our master, the Prophet (peace and blessings be upon him) said, "Do not cause harm and do not reciprocate harm."

It has been proved that smoking, in all its various forms, is harmful to our health, and is therefore unlawful. Assistance towards a prohibition is a prohibition in itself because means are given the same rulings as their goals.

Based on this and in reference to the question, it is impermissible for the inquirer to establish the above mentioned factory.

And God Almighty knows best