Can an minor orphan claim their inheritance when they turn 18?

The money would usually be in a trust that's administered by a representative, often an attorney.

Eighteen-year olds have reached the age of majority, which means they can legally accept inheritances. Unless the money was placed in a trust which specifies a particular age for you to begin receiving distributions, you are eligible.

That depends on many factors, but if it's just sitting there with no stipulations, then sure.

If there was no will, then yes the minor would get it at 18. But that's not how it's done. No one in their right mind would leave money to an 18 year old.

Trust funds are how wealthy families stay wealthy. Usually the fund owns stock or land. And there will be a trustee in charge of the money. There are thousand of ways to set it up, but the typical way is to have an aunt as the trustee. If there are no relatives at all, then the trustee would be a lawyer or a banker.

Sometimes it happens that a kid gets their inheritance at 18. It almost always goes bad.

See a lawyer.

The bequest is held in trust until the recipient achieves majority (or it may be later than that, depending on the Will). Once you achieve the age when it becomes yours, it's yours. The trust winds up and you are handed the assets. Sometimes the trustees can allow early disbursements from the trust funds, for instance for school fees.

The details would be spelled out whatever document that the inheritance would go to him. There would have to be trustee of some sort in possession of the money.