The phrase "a requirement when" is correct and usable in written English.
It can be used to indicate a condition or stipulation that must be met in a specific situation or context.
Example: "Submitting your application is a requirement when applying for the scholarship."
Alternatives: "a condition when" or "a prerequisite when".
The latter became a requirement when the association became tax-exempt in 1999.
Why make it a requirement when it contributes to lowering high-school graduation rates?
"I would think it's a requirement, when you look at the quantity and frequency of recalls," he said.
To George's list we need to add the short-termism that is almost a requirement when such a model dominates.
As a requirement when learning to play a musical instrument the most commonly seen scores are available in paper copies.
Open-drive compressors are a requirement when using a refrigerant such as ammonia, which is not compatible with copper used in electric motors.
Being proactive--a key requirement when looking for new opportunities--I contacted some of the people I had met and visited GlaxoWellcome to meet with the person (a fellow physicist) who would later become my manager.
Carrying out a risk assessment is a legal requirement when planning any outing.
Insurance is not a legal requirement when you are a life coach but it will help to provide peace of mind for your clients and also for yourself in your own practice, in the unlikely event that something went awry.
The need for robust reagents becomes a mandatory requirement when moving from a pure research setting to analyzing sample specimens from clinical development programs.
A PEEP of 1 cmH2O (PEEP1) is a technical requirement when FRC is measured using the proprietary modified wash-in/wash-out technique (GE Healthcare, Madison, WI, USA) and served as the least value for end-expiratory airway pressure [8].
