A closure device for monitoring leakage of a process fluid through a bore of a compressor casing is provided. The closure device may include a body configured to be detachably coupled with the compressor casing about the bore of the compressor. The body may define a fluid passage and a plurality of grooves. The plurality of grooves may be defined about an outer circumferential surface of the body and may be axially spaced from one another. The closure device may also include a plurality of seals at least partially disposed in respective grooves of the plurality of grooves. The plurality of seals may be configured to engage an inner surface of the compressor casing such that adjacent seals of the plurality of seals at least partially define an annular gap therebetween fluidly coupled with the fluid passage and configured to contain the leakage of the process fluid.