Did Iran deal pass congress

It's complicated. The simplest answer is to say that Congress could not "unapprove it".

Under a typical treaty analysis, President Obama would be required by the US Constitution to get Senate ratification of the treaty with a two-thirds majority. However, Obama argued that the Iran Deal was an "executive agreement" and not a "treaty". As an executive agreement, the President is not required to seek Congressional approval, but he may grant Congress the right to vote up or down on the agreement. This up or down vote is a plain majority vote in the Congress, but can be vetoed by the President. This effectively makes the approval requirement for an "executive agreement" the almost-exact reverse of the approval requirement for a "treaty". Instead of two-thirds of the Senate being required to approve a "treaty", now, two-thirds of the Senate and two-thirds of the House of Representatives are required to override the Presidential veto preventing their disapproval of the "executive action" from coming to pass. Congress was not able to muster the two-thirds needed to oppose the Iran Nuclear Deal.

Note that Obama is not the first or only President to use this legal finagling in order to avoid a direct Senate vote. "Executive Agreements" were first invented by Franklin D. Roosevelt and were used by all subsequent US Presidents.