A well was expected to produce with a GOR of 100 m3/m3 but the actual GOR turned out to be 5x higher. As a result, when started up and lined up to the station its production resulted in slugging operation. To prevent slugging a Well Test Unit was hooked up at the well site. As a result, pressure was also building up in the A-annulus and was exceeding the MAASP. The pressure from the A-annulus was bled off to the Well Test Unit using the outer Side Outlet Valve. This was done several times and led to the washing out of the valve body resulting in a leak. That leak occurred 3 days after the Well Test Unit was put into operation. By closing the inner SOV the leak was arrested and the well remained in operation via the tubing and the Well Test Unit to the station for several days before the leaking valve was replaced.