API RP 7HU1-2009 pdf download.Safe Use of 2-inch Hammer Unions for Oilfield Applications.
2.1.1 failure Mechanical separation of the female/male union components, especially under pressure, such that the equipment no longer is able to perform in the manner intended. 2.1.2 figure number A designation used by manufacturers of hammer union components to indicate the general design characteristics. NOTE Depending on the manufacturer and specific design, figure number may represent pressure rating, specific geometric configuration of a union (e.g. flat-faced, misaligning, etc.), electrical insulating capability, etc. of the union type and its components. 2.1.3 incompatible Hammer union components that have the same nominal size, but different pressure ratings, materials and/or geometry. 2.1.4 inspection Comparison of equipment conformity to predetermined standards, followed by a determination of action required, if any. 2.1.5 maintenance Actions to include adjustments, cleaning, lubrication, and replacement of consumable components, as necessary to maintain the serviceability of the equipment. 2.1.6 manufacturer Individuals or companies manufacturing (or who have manufactured) equipment or materials covered by this RP. 2.1.7 mismatch Connecting hammer union components that have the same nominal size, but different pressure ratings, material and/ or incompatible geometry. 2.1.8 testing Actions that are carried out on a piece of equipment to determine if that equipment can perform its intended function. 2.1.9 users Individuals or companies responsible for the use of equipment or material, or implementing recommended practices. 2.1.10 walk-the-lines The activity of checking the equipment directing the flow of fluid (from high pressure to low pressure) along each branch of the process ensuring that each item of equipment is suitably rated and matched to the physical and environmental conditions to which it is exposed by the operations.
3 Mismatch Description 3.1 General The most common designations in the petroleum industry for hammer union components with the potential for mismatch, and which are covered by this RP are: — 2-inch Figure 402, — 2-inch Figure 602, — 2-inch Figure 1002, and — 2-inch Figure 1502. These hammer union components have a history of failing under pressure due to incorrect matching of components (pressure ratings and/or incompatible geometry). The list of hammer union components that can be incorrectly matched is not meant to be all-inclusive. Users should establish controls to ensure hammer union combinations are safe, especially when more than one manufacturer’s components are used. 3.2 Example of the Hazard The mismatching of either the female 2-inch Figure 402, female 2-inch Figure 602 or the female 2-inch Figure 1002 hammer union component (sub) with a male 2-inch Figure 1502 hammer union component (wing nut) is a worldwide issue in the industry and can cause serious incidents, including fatalities. Complete and proper make-up of hammer union components is required to attain the rated working pressure of the equipment. The root cause of the mismatch is that the 2-inch Figure 402, 2-inch Figure 602 and 2-inch Figure 1002 unions were designed with the same thread pitch as the 2-inch Figure 1502 and the female subs have a major (external) thread diameter that is just large enough to engage the minor (internal) diameter of the 2-inch Figure 1502 wing nut internal acme thread. Consequently, although these mismatched hammer union components (2-inch Figure 1502 wing nut with a 2-inch Figure 402, Figure 602 or Figure 1002 female sub) may fully make-up and hold some level of pressure, an explosive failure of the mismatched unions will occur well below the rated working pressure of any of the components, putting people and property at risk. See IADC Alerts 98-01, 99-33, 00-15, 03-16, and 06-01 for additional information.
4 Description of the Engineering Design Solution 4.1 General The recommendations described herein are intended to be an engineering solution to the mismatch problem by preventing the inadvertent make-up of a female 2-inch Figure 402, 2-inch Figure 602 or 2-inch Figure 1002 sub with the wing nut of the 2-inch Figure 1502 hammer union. Manufacturers are encouraged to implement this engineering solution on all newly manufactured hammer union components. Users should utilize components and assemblies that implement this solution. The engineering design solution involves a change of the 2-inch Figure 402, 2-inch Figure 602 and 2-inch Figure 1002 female sub in three different areas as follows: a) reduced thread major diameter, b) raised shoulder,