They are anchored in mechanical, cup or friction type seating nipples. Depending on the barrel type (thin/heavy wall, travelling/non-travelling) and seating nipple placement (top/bottom) these pumps have special designations: according to Russian standard GOST: NB1B and NB2B , according to API 11-AX: RHAM, RHBM, RWAF, RWBF, RHTFS, RHAC, RHBC. Insert pumps manufactured by ELKAM have nominal size from 1 1/16” up to 2 1/4” and can be customized according to the customer’s requirements.