Spanish to English Bus/Financial Law (general)

I would like to know if this phrase necessarily means that it is a written agreement or if two parties can just be in agreement. In these Coast Guard regulations, some places use "se establecerá acuerdo", but two examples of "bajo acuerdo" are:
1. Bajo acuerdo de ambas partes, las conexiones se mantendrán bloqueadas.
2. Los sistemas de agua contra incendio se presurizarán previamente, o se asegurará bajo acuerdo que podrán ser presurizados de inmediato.

Any help would be appreciated