Under 1919.20(a), what must be done when a derrick or associated permanent fitting is found deformed in service between surveys?
You must subject the deformed derrick or permanent fitting to a proof test to determine if it is safe to continue in service. Under 1919.20(a), if the proof test shows the derrick or fitting can remain in service without repair, the existing deformity must be noted on the test certificate. The provision is applied in conjunction with the survey requirements in 1918.51(b).