API 11B Double Packed Stuffing Box


1. Introduction of stuffing box

The stuffing box is installed on the wellhead to seal polished rod to prevent crude oil spill well.

2. Material

2.1. Chemical Composition

The chemical composition of stuffing boxes shall be any composition of AISI recommended series materials listed below which meet the mechanical property requirements. The chemical composition and limits shall be detailed in the material specification of the manufacturer.

a) ASTM A395 ductile iron ,or equivalent international series number.

b) Carbon steel: AISI 1018  to 1045, or an equivalent international series number steel.

c) Alloy steel: AISI 4130 to 4140, or an equivalent international series number steel.

2.2. Material Requirements

The minimum material tensile strength shall be 60000 psi(414 MPA) and the minimum material yield strength shall be 40000 psi( 276MPa)

3. Specification

Stuffing boxes are furnished for the polished rod sizes Nominal thread connection size of stuffing boxes is in accordance with the size and type of bottom connection. The bottom connection is either upset or non-upset external tubing threads conforming to API 5B.


Bottom connection (NUE, EUE)

Working pressure


Working temperature


1-1/8” (28.58mm)

2-3/8”, 2-7/8”, 3-1/2”, 3”LP

1500, 2000, 3000


1-1/4” (31.75mm)

1-1/2” (38.10mm)

1-3/4” (44.45mm)