What is the legal ruling for establishing factories manufacturing metals used in fabricating water pipes?

Islam has prohibited everything that harms man both physically or psychologically.
Allah Almighty says: Who commands them to do the right and forbids them to do wrong [7:157].

Good things include what benefits man both physically and psychologically while bad things include what harms him physically, psychologically, or both. Allah Almighty says: Do not contribute to your destruction with your own hands [2:195] and our master, the Prophet , said: "Do not cause harm and do not reciprocate harm".

It has been proved that smoking, in all its various forms, is harmful to health and 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.

The answer to the question is known from the above and Allah Almighty knows best.