Abstract: A side entry sub has an elongated main body with a longitudinal bore and a side passage intersecting the longitudinal bore. A removable hub has a nose portion which threadably engages mating threads in the side passage, with a resilient seal on the nose portion providing a fluid seal with the main body. The threads are formed such that a flange on the hub advances into contact with the main body with a desired contact force as holes in the flange come into alignment with threaded holes in the main body. Threaded flange bolts through the flange holes engage the threaded holes in the main body. Locking washers, preferably NORD-LOCK® brand locking washers, are used on the flange bolts. The removable hub is structurally connected to the main body by the threaded connection and contact of the flange with the main body, and pressure- and fluid-sealed by the resilient seal.