Don-Nan THB API tubing pumps are heavy-walled, stationary barrel, bottom hold-down pumps recognized by API as a standard design.

THB API Pump

Don-Nan THB API tubing pumps are heavy-walled, stationary barrel, bottom hold-down pumps recognized by API as a standard design. They are often used in shallow wells that produce more fluid than an insert rod pump can accommodate, yet not enough fluid to make an ESP cost effective. Unlike insert pumps, the working barrel of these pumps is a section of the tubing string, which enables them to displace more fluid than insert pumps. The hold-down is an independent piece that is typically inserted in the assembly prior to field delivery. The traveling assembly is installed on the end of the sucker rod string. Tubing pumps include a mechanism on the bottom end of the traveling assembly to retrieve the hold-down assembly should the valve require repair.

Seating options on this pump include cup types suitable for high temperatures and mechanical types for simplified well maintenance. A mechanical hold-down does not require repair unless major damage has occurred, and cups should be replaced every time the pump is unset.
Both hold-down types follow the same procedure of setting and unsetting by placing the weight of the sucker rods down on the pump or by lifting up.