American Petroleum Institute

Safe Use of 2-inch Hammer Unions for Oilfield Applications - FIRST EDITION; ERTA: February 2014
 N RP 7HU1

Annotation

General

This recommended practice (RP) sets forth procedural recommendations as well as an engineering solution to the mismatching of a female 2-inch Figure 402, a female 2-inch Figure 602, or a female 2-inch Figure 1002 hammer union component (sub) with a male 2-inch Figure 1502 hammer union component (wing nut) as described in 3.2. The procedural recommendations described in this RP should be implemented to reduce further incidents.

The engineering solution, which prevents the mating of female 2-inch Figure 402, 2-inch Figure 602 and/or 2-inch Figure 1002 subs with the wing nut of the 2-inch Figure 1502 hammer union, applies to the manufacture of new hammer union components and should not be applied in the modification of existing hammer union components due to unknown factors caused by field wear

Objective

The objectives of this RP are as follows.

a) Raise awareness of the incompatibility of these hammer union components, whereby these components will mate improperly when threaded together; and are likely to fail explosively below the rated working pressure of the hammer union parts (male or female).

b) Describe a recommended procedural solution to the industry that will reduce the likelihood of a 2-inch Figure 402, 2-inch Figure 602 and/or 2-inch Figure 1002 hammer union component being made-up inadvertently to a 2-inch Figure 1502 hammer union component. This procedural solution is critical because, depending on industry acceptance and implementation, the engineering solution might take years to effectively eliminate industry equipment manufactured to the original design of 2-inch Figure 402, Figure 602, and Figure 1002 hammer union components.