Can an industry committee sign a contract with a property company without an official seal?

You can't. The property contract must have the official seal of the owners' committee, and it will not take effect without the official seal. Therefore, when the property works in the community, it must find the owners' committee, which will supervise and inspect the property on behalf of all the owners. Sign the contract. Property must accept the supervision and inspection of the owners' committee. The owners' committee regularly reports the performance of the property contract to the owners' congress. The official seal of the owners' committee is valid.