More information is required from the original poster. But what information is required about the foaming? You might address the following and let others advise other information required.
Perhaps the amine type such as MDEA, MEA, DGA, ...?
Perhaps the application such as removal of hydrogen sulfide, carbon dioxide, both, what levels?
Some other gas properties?
Perhaps metalurgical information on the vessel and piping system?
Perhaps operating characteristics related to circulating rates or ratios?
Is the question related to a new unit design or commissioning steps to avoid foaming; or an existing foaming problem in operation?
Perhaps the solution was not stored hygienically and air/ oxygen got in to it. If so, one needs to purge the sytem of the contaminated solution and recharge with correct solution. Big expense.