A bonnet assembly may be coupled to a valve block. The bonnet assembly may include a bonnet body extending, in an axial length, between a first and second end of the bonnet body. Additionally, the bonnet body may have a sealing surface on the second end. Further, a bonnet retainer nut may be provided with passage axially extending through a first end surface to a second end surface. The bonnet retainer nut may be disposed on the bonnet body such that a portion of the bonnet body is enclosed within the passage of bonnet retainer nut. Furthermore, the bonnet retainer nut may lock the bonnet body.